Archive for March, 2006
suite101.com/article
BirdingBy Fred J. Kane
Hirundo pyrrhonota Vieillot The Cliff Swallows usually come into view in early days of May. In summer they stay only in the surrounding area of their usual nesting settlements. The number of this birds breeding in the provinces seems to have declined. Birders see small numbers after the month of August. The average length of the Cliff Swallow is from three to five inches and is a sparrow sized swallow.
The adult Cliff Swallow has dark iridescent blue coloring, rump of buffy orange color; and a white forehead. The top of their head, throat and back are colored black Their cheek and throat are colored chestnut while their chest and the nape of their neck shows gray. The Cliff Swallow has a dark blue, black space on its chest. Their stomach is ivory and the end of their tail is almost square and they have a small beak. Juvenile Cliff Swallows have similar plumage as the adults but duller. The Cliff Swallows build their gourd shaped nest of dirt balls and grass and line the nest with soft grass and feathers. They usually attach the nest to the outside wall under the eaves of a barn or other building. Once in awhile bird watchers see a lone Cliff Swallow nest attached to the outside of a porch or home. Usually the Cliff Swallows nests in colonies. This swallow will nest communally in mud nests in open country near buildings or cliffs, near lakeshores and, under bridges, in barns and caves.
The male courtship flight is followed by strutting on ground for the female. After mating the female Cliff Swallow lays four to five white eggs. The eggs have tiny spots of cinnamon covering the entire outer surface. She begins to lay her eggs around the first days of June and sits on the eggs for about two weeks and in three to 3 ½ weeks the young swallows begin to fledge. Usually the Cliff Swallows have one brood each year.
The Cliff Swallow breeds from the central part of Alaska to northern section of Nova Scotia and south across most of the United States on into Central Mexico. Also bird watcher see the Cliff Swallow through out California except n the southern deserts and at higher elevations The Cliff Swallows migrate and spend their winters from October through February in Brazil and south to other South American countries. Many bird watchers in the agricultural districts believe the House Sparrow caused the decline in the Cliff Swallow population in recent years. The House Sparrow seems to take over the swallow’s mud nests. The House Sparrow takes over the swallow’s nest by fighting with the Cliff Swallow before it even lays her eggs.
 For people who see a Cliff Swallow starting to build its nest on one of their building, it is suggested they dump a pail of water often on clay like soil, to make a mud hole near the birds’ new nest site. The birds will make and gather mud pellets and carry them to their new nests.
Like its close relative the Barn Swallow the Cliff Swallow has taken advantage of man. At one time only building their on cliff faces in the west, Cliff Swallows now nest under bridges, culverts, and the eaves of buildings. Some amateur bird watchers confuse the Cliff Swallow with a Barn Swallow. The Barn Swallow has a deeply forked tail while the Cliff Swallow’s tail is almost square. The buff rump patch worn by the Cliff Swallow is a good field mark and the Barn Swallow’s rump is blue, black in color. Our breeding Cliff Swallows are of the subspecies Hirundo pyrrhonota pyrrhonota of Central and Northwestern North America. Drifting swallows from that region do not appear especially in late fall. The Cliff Swallows diet consists exclusively of insects but sometime eat fruit. They also drink water.
Their voice consists of a continuous high pitched prattle and peeping. A similar species to the Cliff Swallow is the Cave Swallow of Texas and Southwest. The Cliff Swallows usually return on schedule for their publicized arrival on March 19 at The Mission San Juan Capistrano.
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March 29th, 2006
.americanartifacts.com
Richard & Diane Van Vleck - Personal Pages
Barn swallow colony sites are frequently destroyed when old buildings are demolished or sold to new owners, who wish to close them up. Attracting swallows to buildings where they will be allowed to nest has been simply a matter of opening a door or window, perhaps, providing nesting ledges, and leaving the rest to luck. The chances of attracting barn swallows to a specific building are about as good as attracting bats to a bat box. When a building housing a colony of swallows is to be closed, it should be done after the nesting season. Even then, chances are only fair that the colony will establish itself at a safe site the following spring. Homeowners and farmers go to great length to birdproof their garages and other outbuildings to keep out house sparrows. As old barns fall down, fewer and fewer prime swallow sites remain each year, although bridges offer adequate shelter to many colonies. One potential way to establish a new colony in a building is to transport a nest with young from a doomed site. By moving the nest very slowly, the parents will follow and continue to care for the young. When the old site is lost, it would be hoped that the parents, and perhaps, the entire colony would then nest in the new building the following year. The opportunity to test this theory arose in the summer of 1992, when the H.H.S. mail room was closed off to better control humidity.
Our swallow colony is located in the lower part of our barn in a large room (1300 sq ft). A single pair of swallows moved from the colony room to the mail room in 1990. When they could not be discouraged from nest building, I put up a shelf where I wanted the nest and they instantly switched their focus to the shelf. Previously, they were building on various tools hanging on the wall. We now had a working relationship in which I was committed to not forgetting to always leave at least one door open and to stay out of their way as much as possible, and, they seemed to agree to nest on the shelf, and not above stacks of Home Ground or other supplies or tools. In addition, I agreed to not suddenly turn on the lights at night and scare them off the nest.
The swallows and I got along quite well that summer. They had finished their nest late in the season and only raised one brood. However, in 1991, they again refused to nest with the main colony even though I was careful to keep the mailroom doors closed. Whenever I opened the large door to get out my bike, the pair of swallows would instantly enter and check out their empty nest, even though the other swallows had long since begun nesting in the colony room. So, I gave in again and opened the doors for them. They raised two broods that summer, and, although helpers would come to help feed the young, no other nest was ever begun in the mail room. At the same time, new nests were continually being built in the colony room and plenty of space was available in the large room. We apparently had a pair of “loners”. It is likely that at least one of the pair was the same individual each year.
In 1992, the mail room was going to be enclosed to better control humidity, and, the pair of swallows would not be able to nest there. In early summer, it appeared that the swallows had lost interest in the room, so the doors were left open for several days. Five days after the doors were opened a swallow was seen leaving the mail room nest and a clutch of eggs were found in the nest. At this point, I considered trying to move the nest, a little at a time, to the main colony room, but, decided this would be too disruptive to the entire colony. Also, this pair had refused to join the colony on their own for three years, always waiting for the first opportunity to enter the mail room. It was unlikely that I could force them to join the group now. Instead, I decided to move the nest to a room in the upper barn. If they took to this location, it could be theirs for years to come, with no human interference.
Since it was mid-summer, the in-transit nestlings would have to be protected from the sun while the nest was slowly moved 72 feet along the barn and then 14 feet up a ladder to the entrance of their new room. A louvered video monitor case was used for this purpose. The case was mounted on a tripod two feet from the mailroom nest and left in position for two days to allow the adults to become familiar with it.
Preparation for the move began soon after daybreak to allow as much time as possible to complete the move. A shaped piece of hardware cloth was fitted to the nest to prevent it from falling apart and a long bladed knife was gently worked between the nest and the wall to free the nest, which was then placed in the metal case. Since the nest had been built on a swallow shelf, it could be returned to the original position, if the adults didn’t accept the change.
Luckily, after 8 minutes of flying to the nest’s previous position and circling, one of the adults landed on the nest and instantly fed one of the young. Soon both adults were tending to the young as if nothing had happened. After 15 minutes, the box was lowered 2 feet so that the tripod legs rested on the floor. As before, the adults went to the previous position, flying in tight circles, and totally ignoring the nest below. This time they discovered the nest in 5 minutes. Next the box was moved three feet at a time toward the door, which was 20 feet from the original nest site. After each move, the swallows would circle the exact point of the previous location for several minutes before locating the nest.
Once outside, the nest had to be moved 42 feet along the side of the barn, around a corner, and 30 feet further to the new entrance which was 14 feet above the ground. The incremental moves went smoothly until the entrance to the main colony was reached. But, despite some confusion, we reached the corner of the barn not far behind schedule. At one point the adults were frequently perching on a lever of a walking cultivator and, also, having more trouble than usual finding the nest. On the hunch that this perch was providing a reference point for them to find the nest, I began pulling the cultivator along with each nest move, and this appeared to help them find the nest. I had to give this up when we approached the corner of the barn because of several obstacles in the path.
When the nest was moved partially around the end of the barn, the adults were not able to find it. As before, it was in plain site, but after 15 minutes with no success, I moved the nest back to it’s previous position 3 feet away. This did not work either. The adults were now returning to the mail room and flying somewhat randomly around the path we had taken. Out of desperation, I returned the nest to the entrance to the mail room, where it was discovered in 3 minutes. Then, we once again began the 32′ journey to the corner of the barn. This time, I negotiated the corner with very short moves (less than 1 foot). Once around the corner, there were no obstacles and no nearby reference points and the move progressed rapidly. The move up the ladder also went without a hitch. In fact, the swallows seemed to cope with vertical movement better than horizontal. The final step was to very gradually move the nest into the barn, where the adults had, perhaps, never before entered. This, also, went smoothly and the adults seemed to adapt quite nicely to their new room. All four young fledged and the adults had begun construction of a mud nest directly above the tripod-mounted nest. However, the swallow nesting season was winding down and it was much too late to begin a new brood, but, the beginning of a new nest was a hopeful sign that they would return to nest in this room the following year.
In 1993, no swallows were observed entering the new room. Although swallows would occasionally enter the mail room when a door was left open, it appeared that they were chasing insects and not looking for a nest site. There is still hope that one of the swallows that fledged from the new room will return to nest there in the future. While this successful move demonstrates that active swallow nests can be moved from sites in an emergency, such as planned demolition or construction, it offers no evidence that a new colony can be established by such a move.
Addendum: Since the above article was written, no swallows have shown an interest in nesting in the 2nd floor room where the nest was introduced in 1992. The old mail room has served many purposes since then - it is now becoming a woodworking shop. Swallows have been discouraged from nesting there, but they show interest every year, whenever they find the large rear door open.
• barn swallow young in nest before moving. This is a brood of the previous year. Note the small platform nailed to the beam. Providing such shelves serves two important purposes. It allows the human to select where the swallow builds its nest and it provides a safe base to prevent the nest from falling.
• The day before the move, with the moving box in place
• The nest is placed in the moving box. This created a surprisingly difficult problem for the swallows, who hovered 18″ away at the original nestsite, ignoring their nest and young even though they could see and hear the young. After 8 minutes, the new location of the nest was discovered and the young were fed as frequently as usual, the adults going directly to the moving box each time.
• The move begins
• Feeding the young, now 6 feet along on their journey
• At the 12 foot mark - note both adults on the cow skull horn
• Finally outside, the nest is protected from direct sunlight by the louvred box.
• The adults seemed to have adjusted to the enclosed box, but still had difficulty acccepting each small move of the nest.
• The ladder to the second floor opening. A small platform which hooked over the rungs of the ladder allowed incremental moves up the ladder.
• Ready to enter the new room. The box was fitted to the tripod again and moved several feet into the room, where the nesting was allowed to continue undisturbed. Several helpers eventually began to enter the new room and feed the young, just as they had in the previous location. However, when the young fledged, the new room was ignored.
March 29th, 2006
.americanartifacts.com
Richard & Diane Van Vleck - Personal Pages
Barn swallow colony sites are frequently destroyed when old buildings are demolished or sold to new owners, who wish to close them up. Attracting swallows to buildings where they will be allowed to nest has been simply a matter of opening a door or window, perhaps, providing nesting ledges, and leaving the rest to luck. The chances of attracting barn swallows to a specific building are about as good as attracting bats to a bat box. When a building housing a colony of swallows is to be closed, it should be done after the nesting season. Even then, chances are only fair that the colony will establish itself at a safe site the following spring. Homeowners and farmers go to great length to birdproof their garages and other outbuildings to keep out house sparrows. As old barns fall down, fewer and fewer prime swallow sites remain each year, although bridges offer adequate shelter to many colonies. One potential way to establish a new colony in a building is to transport a nest with young from a doomed site. By moving the nest very slowly, the parents will follow and continue to care for the young. When the old site is lost, it would be hoped that the parents, and perhaps, the entire colony would then nest in the new building the following year. The opportunity to test this theory arose in the summer of 1992, when the H.H.S. mail room was closed off to better control humidity.
Our swallow colony is located in the lower part of our barn in a large room (1300 sq ft). A single pair of swallows moved from the colony room to the mail room in 1990. When they could not be discouraged from nest building, I put up a shelf where I wanted the nest and they instantly switched their focus to the shelf. Previously, they were building on various tools hanging on the wall. We now had a working relationship in which I was committed to not forgetting to always leave at least one door open and to stay out of their way as much as possible, and, they seemed to agree to nest on the shelf, and not above stacks of Home Ground or other supplies or tools. In addition, I agreed to not suddenly turn on the lights at night and scare them off the nest.
The swallows and I got along quite well that summer. They had finished their nest late in the season and only raised one brood. However, in 1991, they again refused to nest with the main colony even though I was careful to keep the mailroom doors closed. Whenever I opened the large door to get out my bike, the pair of swallows would instantly enter and check out their empty nest, even though the other swallows had long since begun nesting in the colony room. So, I gave in again and opened the doors for them. They raised two broods that summer, and, although helpers would come to help feed the young, no other nest was ever begun in the mail room. At the same time, new nests were continually being built in the colony room and plenty of space was available in the large room. We apparently had a pair of “loners”. It is likely that at least one of the pair was the same individual each year.
In 1992, the mail room was going to be enclosed to better control humidity, and, the pair of swallows would not be able to nest there. In early summer, it appeared that the swallows had lost interest in the room, so the doors were left open for several days. Five days after the doors were opened a swallow was seen leaving the mail room nest and a clutch of eggs were found in the nest. At this point, I considered trying to move the nest, a little at a time, to the main colony room, but, decided this would be too disruptive to the entire colony. Also, this pair had refused to join the colony on their own for three years, always waiting for the first opportunity to enter the mail room. It was unlikely that I could force them to join the group now. Instead, I decided to move the nest to a room in the upper barn. If they took to this location, it could be theirs for years to come, with no human interference.
Since it was mid-summer, the in-transit nestlings would have to be protected from the sun while the nest was slowly moved 72 feet along the barn and then 14 feet up a ladder to the entrance of their new room. A louvered video monitor case was used for this purpose. The case was mounted on a tripod two feet from the mailroom nest and left in position for two days to allow the adults to become familiar with it.
Preparation for the move began soon after daybreak to allow as much time as possible to complete the move. A shaped piece of hardware cloth was fitted to the nest to prevent it from falling apart and a long bladed knife was gently worked between the nest and the wall to free the nest, which was then placed in the metal case. Since the nest had been built on a swallow shelf, it could be returned to the original position, if the adults didn’t accept the change.
Luckily, after 8 minutes of flying to the nest’s previous position and circling, one of the adults landed on the nest and instantly fed one of the young. Soon both adults were tending to the young as if nothing had happened. After 15 minutes, the box was lowered 2 feet so that the tripod legs rested on the floor. As before, the adults went to the previous position, flying in tight circles, and totally ignoring the nest below. This time they discovered the nest in 5 minutes. Next the box was moved three feet at a time toward the door, which was 20 feet from the original nest site. After each move, the swallows would circle the exact point of the previous location for several minutes before locating the nest.
Once outside, the nest had to be moved 42 feet along the side of the barn, around a corner, and 30 feet further to the new entrance which was 14 feet above the ground. The incremental moves went smoothly until the entrance to the main colony was reached. But, despite some confusion, we reached the corner of the barn not far behind schedule. At one point the adults were frequently perching on a lever of a walking cultivator and, also, having more trouble than usual finding the nest. On the hunch that this perch was providing a reference point for them to find the nest, I began pulling the cultivator along with each nest move, and this appeared to help them find the nest. I had to give this up when we approached the corner of the barn because of several obstacles in the path.
When the nest was moved partially around the end of the barn, the adults were not able to find it. As before, it was in plain site, but after 15 minutes with no success, I moved the nest back to it’s previous position 3 feet away. This did not work either. The adults were now returning to the mail room and flying somewhat randomly around the path we had taken. Out of desperation, I returned the nest to the entrance to the mail room, where it was discovered in 3 minutes. Then, we once again began the 32′ journey to the corner of the barn. This time, I negotiated the corner with very short moves (less than 1 foot). Once around the corner, there were no obstacles and no nearby reference points and the move progressed rapidly. The move up the ladder also went without a hitch. In fact, the swallows seemed to cope with vertical movement better than horizontal. The final step was to very gradually move the nest into the barn, where the adults had, perhaps, never before entered. This, also, went smoothly and the adults seemed to adapt quite nicely to their new room. All four young fledged and the adults had begun construction of a mud nest directly above the tripod-mounted nest. However, the swallow nesting season was winding down and it was much too late to begin a new brood, but, the beginning of a new nest was a hopeful sign that they would return to nest in this room the following year.
In 1993, no swallows were observed entering the new room. Although swallows would occasionally enter the mail room when a door was left open, it appeared that they were chasing insects and not looking for a nest site. There is still hope that one of the swallows that fledged from the new room will return to nest there in the future. While this successful move demonstrates that active swallow nests can be moved from sites in an emergency, such as planned demolition or construction, it offers no evidence that a new colony can be established by such a move.
Addendum: Since the above article was written, no swallows have shown an interest in nesting in the 2nd floor room where the nest was introduced in 1992. The old mail room has served many purposes since then - it is now becoming a woodworking shop. Swallows have been discouraged from nesting there, but they show interest every year, whenever they find the large rear door open.
• barn swallow young in nest before moving. This is a brood of the previous year. Note the small platform nailed to the beam. Providing such shelves serves two important purposes. It allows the human to select where the swallow builds its nest and it provides a safe base to prevent the nest from falling.
• The day before the move, with the moving box in place
• The nest is placed in the moving box. This created a surprisingly difficult problem for the swallows, who hovered 18″ away at the original nestsite, ignoring their nest and young even though they could see and hear the young. After 8 minutes, the new location of the nest was discovered and the young were fed as frequently as usual, the adults going directly to the moving box each time.
• The move begins
• Feeding the young, now 6 feet along on their journey
• At the 12 foot mark - note both adults on the cow skull horn
• Finally outside, the nest is protected from direct sunlight by the louvred box.
• The adults seemed to have adjusted to the enclosed box, but still had difficulty acccepting each small move of the nest.
• The ladder to the second floor opening. A small platform which hooked over the rungs of the ladder allowed incremental moves up the ladder.
• Ready to enter the new room. The box was fitted to the tripod again and moved several feet into the room, where the nesting was allowed to continue undisturbed. Several helpers eventually began to enter the new room and feed the young, just as they had in the previous location. However, when the young fledged, the new room was ignored.
March 29th, 2006
hkfsta.com.hk/articles
Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University
Shun Wan CHAN
Abstract: Edible bird’s nest is one of the widely used health foods in Chinese communities. The market generated by it is increasing because it exhibits a lot of beneficial effects to human beings. For its high market value, fake edible bird’s nest and misleading promotional description emerged. This article briefly reviews the scientific research on authentication technologies and pharmacological effects of edible bird’s nest. It is expected that people’s knowledge on edible bird’s nest could be enhanced.
Background
Swiftlets (collocaliini) are tiny insectivorous birds that are distributed from the Indian Ocean , through Southeast Asia and North Australia to the Pacific[1]. Amongst various species of swiftlets in the genus of Collocalia, only the nests of four species habituating in the Southeast Asian region have commercial value because of human consumption. They are Collocalia fuciphaga, Collocalia germanis, Collocalia maxima and Collocalia unicolor[2]. Collocalia species, average 6.5g in weight, have glossy plumage[1]. Their nests are constructed with salivary glue, a cementing substance, and may incorporate other materials such as vegetation or feathers. It takes about 20 days to finish the nest. The edible bird’s nest ( 燕窩 in Chinese) making up with purely salivary glue are much more expensive than those incorporating with other materials (see Figure 1 in p.40).
In Hong Kong and in Chinese societies throughout the world, traditional Chinese medicine (TCM) is commonly used to treat diseases and enhance health. It is believed that TCM herbs have wide-ranging effects for enhancing health, lowering risk of diseases and promoting life span [3,4,5]. Being one of the TCMs, edible bird’s nest is believed to have health enhancing effects such as anti-ageing, growth promoting and immunoenhancing properties. In fact, the medicinal use of edible bird’s nest can be traced back to 17th century[6]. However, edible bird’s nest is different from most of the TCMs. It is not only a medicine to make people healthy but also a pleasant food. Traditionally, it is double boiled with rocky sugar to make a delicacy known as “bird’s nest soup”.
Although the size of Collocalia is small, the market generated by it is tremendous. The estimated market of edible bird’s nest in 2004 is worth about HK$ 3 billions in Hong Kong . The local market is the world’s largest consumer of edible bird’s nest[2,7]. The annual percentage increase of the local market is in doubledigit[7]. It may be due to the fact that Hong Kong people are more and more concerned about their health and the status of TCM has risen after a series of government policies on TCM. Moreover, a dual nature of edible bird’s nest, that could be treated as medicine or/and food, may play a role. In the past, people could only buy dried edible bird’s nests. For the advancement in food technology, large variety of edible bird’s nest related products emerge to the market. They are readily to serve products. No cooking process is required. Amongst those new products, most of them are still in the traditional form as bird’s nest soup, such as instant bird’s nest in different concentrations. Some instant bird’s nest may also supplement with other TCMs. Apart from the traditional form, there is a trend of using edible bird’s nest extract as one of the chief ingredients of the products. These products focus mainly on the medicinal use of edible bird’s nest. However, some of them may exaggerate the therapeutic use of edible bird’s nest. For the limited supply and high price of edible bird’s nest, it is not uncommon to hear reports of fake edible bird’s nest in the market. The imitation substitute commonly used is the edible plant-exude, gum karaya or sterculia[8]. Recently, there are reports of fake edible bird’s nest made from fishes’ skin, mushroom or algae in China [9]. Therefore, it is a great concern on authenticating the genuineness of edible bird’s nest. In this review, the author will briefly summarize some advanced technologies in authenticating edible bird’s nest. The medicinal benefits of edible bird’s nest with contemporary scientific evidence will also be given.
Authenticity of Edible Bird’s Nest
The first comprehensive report on authentication of edible bird’s nest can be traced back to the early 1990s. Sam et al., (1991) demonstrated the possibility to use scanning electron microscopy, energy dispersive X-ray microanalysis, flame atomic emission spectroscopy, inductively coupled plasma-atomic emission spectroscopy, ultraviolet-visible spectroscopy and other physico-chemical techniques to ascertain the authenticity of edible bird’s nest[8]. Since they only made a comparison with some imitation bird’s nest with substances from plant origins, it limited the generalizing ability of the techniques to other imitation materials. In addition, they relied on sophisticated equipment. It is hard for commercial testing laboratories to carry out. Recently, a research team in China has developed a simple but accurate and reliable spectrophotometry method to determine edible bird’s nest content[10]. It could also be used to differentiate genuine edible bird’s nest with saliva, pig’s skin and Tremella fucifomis[10]. The method is based on the reaction between N-acetylneuramic acid and ninhydrin in acid solution. The method evaluates the internal content of N-acetylneuramic acid, a nine-carbon sugars, which is one of the major components in edible bird’s nest.
Nutritional Content and Medicinal Use
Edible bird’s nest contains mainly carbohydrates, amino acids and mineral salts. The major ingredients of edible bird’s nest are glycoproteins[11]. Amongst the carbohydrates in edible bird’s nest, sialic acid (9%) is the major one. It was found that exogenous source of sialic acid may contribute to neurological and intellectual advantages in infants[12]. However, the nutritional and biological mechanisms of sialic acid in human body are still under investigation. The other major carbohydrates include 7.2% galactosamine, 5.3% glucosamine, 16.9% galactose and 0.7% fucose[11].
Amino acids and mineral salts are also important components in edible bird’s nest. Three non-essential amino acids (aspartic acid, glutamic acid, praline) and two essential amino acids (threonine and valine) can be found[11]. They could facilitate normal body functions such as repairing and immunity. Edible bird’s nest is rich in mineral salts. It contains high content of sodium and calcium. It is because the source of edible bird’s nest is derived from saliva Collocalia inhabiting mainly in limestone caves. In addition, low levels of magnesium, zinc, manganese and iron are also detected in edible bird’s nest[8].
In spite of the long history of using edible bird’s nest for medicinal purposes, there are not many scientific researches related to the therapeutic use of it in literature. The first scientific evidence was given by Ng et al. (1986) in Hong Kong. Edible bird’s nest aqueous extract was found to potentiate mitogenic response of human peripheral blood monocytes to stimulation with proliferative agents, Concanavalin A and Phytohemagglutinin A[13]. It suggested that edible bird’s nest might possess immunoenhancing effect by aiding cell division of immune cells.
One year later, other scientific evidence was published by Kong et al. They demonstrated an epidermal growth factor (EGF)-like activity in aqueous extract of edible bird’s nest that stimulated the DNA synthesis in 3T3 fibroblast in a dose dependent manner in vitro[6]. EGF is a 6,000 Da polypeptide hormone produced by glands of the gastrointestinal tract, namely the salivary and Brunner’s glands. It appears to play a crucial role in major normal cellular processes such as proliferation, differentiation and development[14]. It may offer a rationale for the medicinal use of edible bird’s nest in ageing resistance. Since the receptor for EGF is highly expressed in a number of solid tumors, including breast, head-and-neck, non-small-cell lung, renal, ovarian and colon cancer[15], people are worried about a possibility to induce tumor progression and to resist chemotherapy/radiation treatment in tumor cells; in consequence, suggest that cancer patients should avoid edible bird’s nest. In fact, there is no evidence supporting this suggestion. Currently we have evaluated the effects of aqueous extract of edible bird’s nest on the viability on two human cancer cell lines, human breast cancer MCF-7 (ATCC HTB-22) and human liver cancer HepG2 (ATCC HB-8065). There was no observable effect on cell viability when comparing with the control group (unpublished data).
In 1994, a research team in China, evaluated the pharmacological effects of edible bird’s nest and pearl powder containing formulation. The formulation was demonstrated to have immunoenhancing effects by elevating DNA synthesis of T-lymphacytes and circulating immunoglobulin M content in mice. In addition, the formulation also showed ageing retardation by increasing the level of superoxide dimutase[16]. However, the study did not explore whether the effects came from either edible bird’s nest, pearl powder or both.
Further Studies
Edible bird’s nest has been used for several hundred years. Its usage is based mainly on historical, anecdotal and observational reports of its benefit. Scientific evidence for its efficacy is still limited. The putative health benefits such as resisting ageing and improving immunity of edible bird’s nest may be linked, at least in part, to EGF-like activity and mitogenic factor. However, there may be other mechanisms involved. In addition, there may be additive, synergistic or antagonistic effects between different components of edible bird’s nest. Work is needed to establish health-related effects of edible bird’s nest, for example, through assessing biomarker response, isolating and identifying the active components and investigating their possible interaction. In Hong Kong, many people take edible bird’s nest regularly. It is worth establishing epidemiological study to measure relationship of consistent use of edible bird’s nest and its putative beneficial effects in human beings. For the large market of edible bird’s nest, developing a systematic method to identify the sources of edible bird’s nest and check the authenticity of its sample is, undoubtedly, indispensable.
Acknowledgements
The author is grateful to Imperial Bird’s Nest International Company Limited for providing intact bird’s nests and their photos. Special thanks go to Ms. Siu-Hung Tsui for editorial assistance.
References
[1] Lee, P.L., Clayton, D.H., Griffiths, R. & Page, R.D. (1996) Does behavior reflect phylogeny in swiftlets (Aves: Apodidae)? A test using cytochrome b mitochondrial DNA sequences. Proc Natl Acad Sci U S A. 93:7091(7096.
[2] Lau, A.S.M. & Melville, D.S. (1994) International Trade in Swiftlet Nests with Special Reference to Hong Kong (Traffic Inter-national, Cambridge, U.K.).
[3] O’Hara, M.A., Kiefer, D., Farrel, K. & Kemper, K. (1998) A review of 12 commonly used herbs. Arch Fam Med. 7:523(536.
[4] Craig, W.J. (1997) Health-promoting properties of common herbs. Am J Clin Nutr. 70:491S(499S. [5] Yuan, R. & Yuan, L. (2000) Traditional Chinese medicine: an approach to scientific proof and clinical validation. Pharm Therapeut. 86:191(198.
[6] Kong, Y.C., Keung, W.M., Yip, T.T., Ko, K.M., Tsao, S.W. & Ng, M.H. (1987) Evidence that epidermal growth factor is present in swiftlet’s (Collocalia) nest. Comp Biochem Physiol B. 87:221(226.
[7] Leung, C.Y. (2004) Three billions market competition for edible bird’s nest shops. Economic Digest. 1197:68(69.
[8] Sam, C.T., Tan, P.H. & Lim, C.H. (1991) Establishing the authenticity of edible bird’s Nest. ISFM Medicine Scientific Review. 3:1(4.
[9] Li, X., Xi, X. & Che, W. (2003) Analysis and assessment of quality in import-export bird nest. Guangzhou Food Science and Technology. 19:72 & 89.
[10] Huang, H, Xi, X., Chen, W. & Chen, J. (2003) Determination of content of bird nest by spectrophotometer. Guangzhou Food Science and Technology. 19:68.
[11] Kathan, R.I.I. & Weeks, D.I. (1969) Structure studies of collocalia mucoid. I. Carbohydrate and amino acid composition. Arch Biochem Biophys. 134:572(576.
[12] Colombo, J.P., Garcia-Rodenas, C., Guesry, P.R. & Rey, J. (2003) Potential effects of supplementation with amino acids, choline or sialic acid on cognitive development in young infants. Acta Paediatr Suppl. 92:42(46.
[13] Ng, M.H., Chan, K.H. & Kong, Y.C. (1986) Potentiation of mitogenic response by extracts of the swiftlet’s (Collocalia) nest. Biochem Int. 13:521(531.
[14] Yano, S., Kondo, K., Yamaguchi, M., Richmond, G., Hutchison, M., Wakeling, A., Averbuch, S. & Wadsworth, P. (2003) Distribution and function of EGFR in human tissue and the effect of EGFR tyrosine kinase inhibition. Anticancer Res. 23: 3639(3650.
[15] Herbst, R.S. & Langer, C.J. (2002) Epidermal growth factor receptors as a target for cancer treatment: The emerging role of IMC-C225 in the treatment of lung and head and neck cancer. Semin Oncol. 29:27(36.
[16] Zhang, M., Wang, D. & Wang, J. (1994) The effect of the ZHENZHU-YANWO extracts on animal function. Pharmaceutical Biotechnology. 1:49(51.
March 28th, 2006
wildasia.net
contributed by Reza Azmi
Gomantong Hill is the largest limestone outcrop in the Lower Kinabatangan area, and contains at least nine caves. For centuries, the Gomantong Caves have been renowned for the valuable edible birds’ nests made by two of the four species of swiftlets that roost in the caves. During the harvesting months, visitors may be able to witness the birds’ nest collectors in action. This is an age-old tradition and the trade history of bird nest spans several hundreds of years.
The birds’ nests harvesters are individuals who have nerves of steel and skills honed through years of experience. Dangling precariously from the narrow network of ladders is not a task for the faint hearted! It is not surprising that there are only a few experienced individuals who are very much in demand by people and communities that hold the Governments harvesting licenses. Edible birds’ nests are protected under the Birds Nest Ordinance and the Forest Enactment. Heavy fines and penalties are imposed on unlicensed collectors.
Birds’ nest harvesters usually stay in huts close to the entrances of the caves. Their responsibilities are two-fold - they must harvest the nests according to a biologically sustainable schedule (imposed by the Wildlife Department), and they must also protect the nests from being stolen. The failure to adequately carry out either of these roles could have devastating effects on the swiftlet population and subsequent harvests.
Swiftlets have a slow breeding cycle, and usually lay not more that two eggs each season. Generally, two collections are made. The first takes place early in the breeding season before the swiftlets lay their eggs. The birds then make another nest in which they finally lay their eggs. After the young have fledged, the second collection is made. Care must be taken to assure that the nests are collected only after the young swiftlets have abandoned these nests.
Breeding seasons are particular to different species and the different caves in which the birds roost. At Gomantong Caves, the two edible swiftlet species have different breeding times. For the black-nest swiftlet, the first collection should take place no later than April or May, otherwise the birds will not have time to build another nest. The second harvest then takes place in September and October. The more valuable white-nest swiftlet nests are initially collected in February, and again in June and July. The breeding patterns of the birds are not rigid and must be closely monitored to accommodate any observable changes in their reproductive behaviour.
Tools of the trade
The birds’ nest harvesters who are called tukang pemungut still employ time-tested techniques that have been used for hundreds of years. The main prop is the gugulug, a ladder made from coils of rattan rotan saga (Calamus caesius) and hardened belian (Eusideroxylon zwageri or Borneon Ironwood) which may be up to 150 metres in length.
The pietau, is another ladder which usually consist of a rigid bamboo pole about 25 metres long. Rungs are fastened across the bamboo as steps, and additional rattan cords are tied around it to offer some security to the climber. Harvesters use a sesungkit to remove the nests, which are just out of reach. It is a thin hand-held stick of bamboo or light hardwood, which has four sharp steel or bamboo points to dislodge the nests from the cave surface.
The harvester must assess the best combination of these props to be used, based on experience and the location of the nests. When collected, the nests are placed in the ambong, a woven basket that is then lowered to assistants who empty the nests into a large sack.
Other activities
Besides observing the exciting display of skill and courage by the birds’ nest harvesters, another activity for keen naturalists would be to watch the spectacular display of over 2 million or so resident bats as they spiral out for their evening feed. This usually occurs between 5.15 - 6.15pm, but rain sometimes delays or “cancels” this show-time. At the same time as the bats leave, the swiftlets are usually beginning to make their way back to the caves after a day’s foraging. The changing of ’shifts’ between the bats and birds makes quite a fascinating scene! Look out for the Bat Hawks that are not offer far from the scene, as they prey specifically on the bats as they leave their roost.
Getting there
It is possible to drive all the way to the Information Centre at the foot of the Gomantong hill. You can also take any of the Sandakan-Sukau buses that will drop you off at the junction to the caves. But be warned, it is about 6 km (3.72 miles) to the caves, so you might want to charter the whole bus for convenience or pay him a little extra to get dropped off at the information centre. If you are already in Sukau, make arrangements with the local bus transport for a day trip to the caves or a stop over on the way back to Sandakan.
Permits
Do check with the Wildlife Department in Sandakan for harvesting times. Otherwise, opening times for the Gomantong Information Centre are as follows:
Monday-Thursday (8am-12.45pm & 2-4.15pm);
Friday (8am-11.35am & 2-4.15pm); and
Saturday (8am-12.45pm).
Entry permits are not required except during harvesting times. Please check with the Wildlife Department for the entry permits before you go.
The entrance gate will be kept opened till the last visitor of the day leaves so please inform the Wildlife Department staff on duty if you intend to leave later than the stipulated opening times.
March 28th, 2006
Friday March 24, 2006
Peace Country Sun, Canada - Mar 24, 2006
Peace Country Sun — While waiting for the spring yard work to start, I try to get out and clean my old bird boxes and even put up a few new ones. Boxes attract birds that normally nest in tree holes, often those left behind by woodpeckers. We have over a dozen cavity nesting species that will use nest boxes, though only a few are comfortable in urban backyards or on acreages.
Nest boxes are widely used across rural areas of the Prairies to attract bluebirds but in the Peace Country those striking birds are a rare occurrence. One County of Grande Prairie resident has had good success with special hollow log structures placed in old cut-blocks south of the Wapiti River. I have also heard occasional reports of bluebirds using nest boxes in the forest fringes southwest of Beaverlodge.
Our most common birdhouse user is the tree swallow. These lively birds, with a white breast and iridescent blue back, nest in open areas and will readily use boxes set up on fence lines or backyard posts. You can recognize a tree swallow nest by all the feathers lining the cup. Chickadees and house wrens also use nest boxes but they prefer houses set up in the bushes.
All nest boxes should have an overhanging roof, ventilation and drainage holes, and a removable panel for cleaning. Use an entrance hole 38 millimetres in diameter for tree swallows and 40 mm for bluebirds. Larger entrance holes will allow starlings to take over the box. Non-native house sparrows will also move into nest boxes but they can usually be discouraged by removing their nesting material once or twice. House wrens and chickadees are small enough to enter through a 29mm hole and that will exclude house sparrows.
Nest boxes should be built from untreated wood and left unpainted. Don’t both with perches as they just provide access for predators. The only maintenance required is cleaning out the boxes in the fall or early spring and making sure that removable panels are securely in place. Boxes should be up by mid-April so that they are ready for occupancy at the beginning of May.
Purple martins will also readily use nest box condos but the only colonies I am aware of in the Peace region are at Winagami Lake. If you know of any other purple martin nesting sites, please pass the information on to the Peace Parkland Naturalists club at (780) 538-5603.
Large nest boxes with 6 - 10 cm holes can be placed near wetlands to attract goldeneye and bufflehead ducks or in more wooded areas for saw-whet owls and kestrels. Robins and eastern phoebes don’t use cavities but a simple ledge mounted under the eaves of a building may keep them from building on top of the light fixture above your door.
Providing nest boxes is a great way to increase nesting habitat for cavity nesting birds especially if you live in an area with few standing dead trees. For more information on building boxes, check out “NatureScape Alberta” or “Nestboxes for Prairie Birds” by Myrna Pearman.
You can also share observations on nesting birds by submitting information to the Federation of Alberta Naturalists. They support a number of interesting programs for volunteer bird watchers so visit their website at www.fanweb.ca or contact their Edmonton office at (780) 427-8124.
March 27th, 2006
The Jersey Journal
Friday, March 24, 2006
BY JENNIFER MOSSCROP
JOURNAL STAFF WRITER
Spring is in the air - well, almost - and for its 10th year, the New Jersey Meadowlands Commission will install 500 tree swallow nest boxes in the Meadowlands in an attempt to keep the little metallic blue and white birds in the area.
Last week, Gabrielle Bennett-Meany, outreach naturalist, and Larry Marciano, of the NJMC, installed about 20 nest boxes along the shoreline at the Mill Creek Marsh in Secaucus.
They plan on installing them in the Kearny Marsh when the weather gets warmer.
Every year more boxes are added and, according to Bennett-Meany, each hosts a pair of tree swallows.
“I’ve never seen a box that was unoccupied,” Bennett-Meany said.
The nest boxes are designed with a hinged roof that allows curious bird-watchers to get a peek at the birds and a small hole for the birds to get in and out.
Nancy Benecki, spokeswoman for the NJMC, said tree swallows thrive in wetlands so the boxes are stuck into the mud flats that hug the shoreline.
When the weather gets warmer and the ground is softer, Bennett-Meany and Marciano will take a boat out along the Mill Creek Marsh shoreline and install 60 more boxes.
The boxes were built throughout the winter by local Boy Scout and Girl Scout troops and members of Pathways to Independence, a nonprofit organization in Kearny that provides vocational training to adults with developmental disabilities.
As for why the NJMC and local volunteers are dedicating so much time to these birds, Benecki said there are two reasons: The tree swallow, which naturally lives in holes of dead trees hollowed out by other birds and animals, is experiencing a decline in its natural habitat due to development in the Meadowlands area. There are not enough dead trees for them to make their homes in.
Also, tree swallows help balance out the ecosystem by eating swarms of mosquitoes and midges, which are gnat-like bugs, that come to the wetlands when the weather gets warm.
“The tree swallows have taken well to the nest boxes,” Benecki said. “And it is easy for volunteers to build them and help provide shelter for the birds.”
March 27th, 2006
home.intekom.com/ecotravel/EZine/Blue_Swallow
The Blue Swallow is an ambassador for a vital South African ecosystem namely grasslands. The South African grasslands form the major portion of our water catchment areas. More than 60% of the Grassland Biome has already been modified - forestry and agriculture playing largest roles. In South Africa only 2,23% of the Grassland Biome is formally conserved. The Grassland Biome is the least conserved, most transformed and therefore most highly threatened of South Africa’s 7 biomes.
The people of South Africa and the Blue Swallows are equally dependent upon the good management of the grasslands as “water factories”. The Blue Swallow is specialised to living in two grassland types in South Africa namely North-Eastern Mountain Sourveld and Natal Mist Belt. Of all the grassland types in South Africa in need of conservation, the two highest priority types are North-Eastern Mountain Sourveld and Natal Mist Belt. Both grassland types are located along the eastern South African escarpment in the Northern Province, Mpumalanga and KwaZulu-Natal.
As a globally threatened species the Blue Swallow, as a component of its unique grassland ecosystems in South Africa and Africa, should be viewed as the ambassador for the conservation of all of the other faunal and floral components and processes of its unique grassland ecosystem. Conserving the Blue Swallow will therefore result in the survival of other unique grassland species for which there is no working group and thus no conservation efforts.
South Africa is world-renowned for its biodiversity. Our grasslands are amongst the richest habitats for this biodiversity and are home to many fascinating endemic bird species, bird species only found in South Africa and nowhere else in the world. Birding is the fastest growing recreational activity in the world. The effective conservation of our bird-life will maintain unique birding areas that foreign tourists will visit and from which local communities will benefit. Protection of South Africa’s high biodiversity systems will be good for biodiversity, good for water quantity and quality, provide tangible benefits to local communities and be good for the Blue Swallow.
Current Conservation Status
The Blue Swallow is considered to be South Africa’s most endangered bird species (Brooke 1984). There are currently 81 known nests and a further 39 possible nests in South Africa and Swaziland. The numbers were obtained after extensive surveys conducted over the past fourteen years. Optimistically it may be possible to add a further ten nests once certain localities in the former Transkei and certain of the tribal trust-land areas in KwaZulu-Natal have been investigated for the presence of Blue Swallows.
An assessment for the total African distribution range of the Blue Swallow in 1985 listed it as near-threatened. By 1994 the Blue Swallow’s status had deteriorated and it is currently considered to be vulnerable (Collar & Stuart 1985, Collar et al. 1994). Since the 1994 assessment at least for South Africa and Kenya the species status has probably deteriorated from vulnerable to endangered (Nasirwa & Njoroge 1996). Countries for which information is minimal at this stage are the Democratic Republic of Congo, Zambia and Mozambique.
As a species of high conservation priority the Blue Swallow, as a component of its unique grassland ecosystems in South Africa and Africa, should be viewed as the ambassador for the conservation of all of the other faunal and floral components and the processes of its preferred grassland ecosystems. The Blue Swallow therefore ensures the long-term survival of other grassland species for which there is no working group and thus no conservation efforts.
Current global population
An optimistic assessment indicates that there are only 1500 breeding pairs of Blue Swallows remaining for their entire African breeding distribution range. The adult breeding population total is approximately 3 000 individuals.
A total of 89 definite and 34 possible breeding pairs are thought to occur in Southern Africa. An estimated 20 breeding pairs occur in Swaziland. In South Africa KwaZulu-Natal contains 51 definite and a further 19 possible nests, Mpumalanga contains 27 definite and a further 3 possible nests and the Northern Province contains 1 definite and a further 2 possible nests.
Elsewhere in Africa, numbers of breeding birds are estimated as follows: 300 pairs in the eastern-highlands of Zimbabwe, with another 100 pairs possible in adjacent Mozambique; 360 pairs in Malawi; 400 pairs in the southern highlands of Tanzania and 100 pairs in each of northeastern Zambia and southeastern Democratic Republic of Congo (DRC), respectively.
Large breeding populations of Blue Swallows currently in protected areas are Nyanga National Park (580 km²) in Zimbabwe (estimate of 200 breeding pairs) and Nyika National Park (3134 km²) in Malawi (conservative estimate of 260 breeding pairs) (Worsley pers comm., Holroyd & Quinni in prep).
Distribution range
The Blue Swallow’s global distribution range is limited to 10 countries in sub-Saharan Africa and is subsequently an intra-African migrant (Turner 1989). It breeds in KwaZulu-Natal, Swaziland, Mpumalanga, Northern Province, eastern Zimbabwe and adjacent Mozambique in southern Africa. In east Africa the Blue Swallow breeds in Malawi, north-eastern Zambia, south-eastern part of Democratic Republic of Congo and south-western Tanzania (Turner 1989). The birds arrive at their breeding grounds in South Africa and Swaziland towards the end of September (Parker 1994), and depart again in mid-April (Keith et al. 1992). From throughout their breeding range the Blue Swallows migrate in the non-breeding season to Uganda, western Kenya, north-eastern part of Democratic Republic of Congo and possibly also north-western Tanzania in central Africa but do not breed there (Earle 1987).
The furthest north that a Blue Swallow has ever been recorded is Kidepo Valley National Park that has its north-western boundary on the border between Uganda and Sudan in the north-eastern part of Uganda (Butchard 1996). The Blue Swallow range states are Democratic Republic of Congo, Uganda, Kenya, Tanzania, Malawi, Zambia, Zimbabwe, Mozambique, South Africa and Swaziland.
Habitat
The Blue Swallow prefers high altitude, high rainfall (> 1000 mm p.a.), undulating, open, primary mist-belt grasslands (Allan et al. 1988). The preferred sour grasslands generally have a sward height of < 0.5 meters. The Blue Swallow ecosystem throughout its breeding range in Africa is characterised by the occurrence of mist, during the birds breeding periods. In South Africa and Swaziland the bird is specialised to and therefore only found within the two grassland types known as north-eastern mountain sourveld and Natal Mist-Belt (Acocks 1975). Natal Mist-Belt is the grassland type in which the Blue Swallow is found at the southernmost limit of its African distribution range - KwaZulu-Natal in South Africa. From information published in 1967 the grassland type in which the Blue Swallow is found in Zimbabwe, Mozambique, Malawi and Zambia appears to be similar to the grassland type known as North-Eastern Mountain Sourveld in South Africa and Swaziland (Wild et al. 1967). At this stage the grassland type in which the birds are breeding in Tanzania and the Democratic Republic of Congo is believed to be similar to that of their range in Zimbabwe, Mozambique, Malawi and Zambia. As yet no information could be obtained on the grassland composition or type that the birds inhabit in north-western Tanzania. In South Africa North-Eastern Mountain Sourveld contains 130 endemic plant species and Natal Mist-Belt contains 51 endemic plant species.
The two grassland types in urgent need of conservation in South Africa are North-Eastern Mountain Sourveld and Natal Mist Belt (Duthie 1994; Low & Rebelo 1996).
Nest, Eggs and Nestlings
Blue Swallows construct a cup-shaped nest out of a mixture of mud and grass. The nest is attached to the wall of natural or artificial holes. Natural holes currently used by the birds are natural sinkholes and Aardvark burrows or artificial sites such as abandoned mine shafts. The birds prefer holes with an overhang under which the nest is constructed so as to protect the exposed cup from the wind and rain. Nests in suitable nest sites are often repaired each breeding season and used over many seasons. Both the male and female contribute to nest building or repair. The female carrying out most of the work.
Two to three eggs are laid at 24 to 48 hours between each successive egg. Only the female incubates the eggs for 14 - 16 days. The female incubates the nestlings. Both the male and female feed the nestlings. At the peak of their development the adult birds arrive at the nest with food for the nestlings at a rate of once every 2 minutes. Nestlings fledge 20 to 24 days after hatching and remain in the nest area for two to three weeks during which time the parents continue feeding them. The nestlings gradually begin feeding themselves during this period. When conditions are favourable Blue Swallows are double brooded, certain pairs being capable of raising two sets of nestlings in a single breeding season. Adverse weather conditions as a result of mist and rain often result in Blue Swallow eggs not hatching or nestlings not fledging (Evans & Bouwman 2000). In some seasons this seriously affects breeding success. Fiscal Shrike has been recorded predating both Blue Swallow eggs and nestlings.
Threats
The major reason for the reduction in surface areas and fragmentation of these two grassland types and the concomitant endangered status of the Blue Swallow has largely been as a result of commercial forestry for the timber, pulp and paper industry (pine, eucalyptus and wattle plantations). The high altitude, high rainfall, mist-belt grassland areas that are characteristic Blue Swallow habitat are unfortunately also highly suited for the commercial cultivation of these exotic trees. In Zimbabwe the borders of Nyanga National Park are easily found as wattle and pine plantations have been planted right up to the edge of the park. Private ownership of the mineral rights to most of the Blue Swallow localities in Mpumalanga represents a current and potential future threat (Evans 1996). Increased tourism activity and development has resulted in the loss of Blue Swallow breeding pairs in the Mac Mac and Graskop Townlands area. This highlights the need for careful consideration and proper planning of tourism ventures (Evans 1997). Other reasons for the decline in and vulnerable status of the Blue Swallow and its grassland habitats are habitat destruction and fragmentation due to potato, maize and sugar cane cultivation, road construction, overgrazing and inappropriate annual burning of grasslands to improve grazing potential. The annual burning of grassland types that should be burnt every two to three year’s results in a drastic decrease in overall biodiversity. A factor resulting in a reduction in the breeding success of Blue Swallows in certain breeding areas is disturbance of the birds at the nest by the young boys herding the cattle on tribal grazing lands (Boycott pers comm).
Conservation
Due to the migratory nature of the Blue Swallow it is necessary to focus conservation action, advocacy and monitoring over its entire distribution range. Conservation activity should be aimed at preventing the status of the Blue Swallow from deteriorating further. This is achieved by working at resolving conflicts between the requirements of the Blue Swallow and the factors threatening the future existence of those requirements.
The Blue Swallow is listed on both Appendix I and II of the international Convention for the Conservation of Migratory Species of Wild Animals (CMS).
Protected Areas, Natural Heritage Sites and Important Bird Areas
Malolotja Nature Reserve (IBA SW001) in Swaziland and Impendle Nature Reserve (IBA SA077) in KwaZulu-Natal are the only formally protected areas holding breeding Blue Swallows; with totals of eight pairs each. Another 22 breeding pairs of Blue Swallows are protected in six Natural Heritage Sites; three in Mpumalanga and three in KwaZulu-Natal. The KwaZulu-Natal Mistbelt Grasslands (IBA SA078), a series of disjointed grassland patches in a farmland mosaic, hold 38-55 Blue Swallow breeding pairs (Johnson et al. 1998). The nine breeding pairs in the Blue Swallow Natural Heritage Site (IBA SA014) in Kaapsehoop represents the highest breeding density for South Africa (1 pr/52 ha) (Allan et al. 1988). The Graskop Grasslands (IBA SA011) and Misty Mountain Natural Heritage Site (IBA SA013) hold 14 and 2 breeding pairs of Blue Swallows respectively. Blyde River Canyon (IBA SA010) contains a single breeding pair with the possibility of a further pair.
End
March 24th, 2006
By Blaine Friedlander Jr. and Krishna Ramanujan
news.cornell.edu/stories/Sept05/BarnSwallows
ITHACA, N.Y. — Even after they have paired with a male, the female North American barn swallow still comparison-shops for sexual partners. And forget personality; the females judge males by their looks — the reddish color of the males’ breast and belly feathers.
If the male’s red breast is not as dark as other males in the population, the female is more likely to leave him and then secretly copulate with another male, according to aCornell University study featured on the cover of the journal Science (Sept. 30, 2005).
“The bad news for male swallows is the mating game is never over,” said lead author Rebecca Safran, who conducted the study while a Cornell postdoctoral researcher in ecology and evolutionary biology and in the Cornell Laboratory of Ornithology. “It is dynamic and continual. This is something that most humans can relate to — think of how much time and money we spend on our looks and status long after we have established stable relationships.”
Barn swallow (Hirundo rustica erythrogaster) males have a wash of reddish-chestnut color from their throats to their bellies, and this color varies among birds from very pale red-brown to a dark rusty-red. Like many songbirds, half of all male barn swallows typically care for at least one young chick that was actually fathered by another bird. Sometimes males even rear an entire nest of illegitimate young. The researchers used this widespread phenomenon of cheating to test the factors that may keep a female barn swallow faithful to her mate.
After all pairs had laid their first set of eggs, Safran removed the eggs so that the females would mate again. Before the females chose their mates for their second nest, Safran captured the males and randomly assigned them to one of three treatments. She either painted their throat, breast and belly with a red marker to enhance their feathers to match the darkest — and most attractive — males in the population, or left them alone or painted them with a clear marker to ensure that results were not biased by the coloring process. Then she let the pairs breed again. She conducted comparative DNA tests on the offspring from the first and second nests.
In the research, all 30 females remained socially paired with their original male mate, but they were sexually active with other males. The males with enhanced color fathered a substantially larger percentage of offspring in their second nests. Males whose color was unchanged fathered the same number or fewer chicks than they had in their first nests. “The study shows that the females are paying close attention to these signals and that they respond quickly to changes in their mate’s appearance,” Safran said.
The reddish breast and belly feathers indicate a male’s quality, such as his health, status or ability to raise young, Safran speculates.
The actual cue that female barn swallows use to assess potential mates differs according to regional tastes. For example, classic studies have shown that in the very closely related European barn swallow (H. rustica rustica), males with long tail feathers attract more mates. Although many previous studies have investigated mating patterns in birds and other animals, this is the first study of its kind to meticulously rule out biases such as age, size and initial variation in signals of male quality, like coloration, and to demonstrate that mate-selection decisions are continual and dynamic. The results of the study have implications for the evolution and upkeep of showy ornamental traits — such as a peacock’s tail or a deer’s antlers — that are costly for males to maintain but give them an edge over rival males.
“If females are assessing mates on a day-to-day basis, it explains why males continue to maintain costly ornaments even when they might appear to have served their purpose,” said co-author Irby Lovette, assistant professor and director of the Lab of Ornithology’s Evolutionary Biology program.
“Our goal is now to understand how certain males keep a better plumage than others,” said Kevin McGraw, Cornell Ph.D. ‘03, one of the co-authors who is now an assistant professor at Arizona State University in Tempe. “Factors like ultraviolet radiation from the sun, soiling and even feather-degrading bacteria are known to affect the color of bird feathers once they are grown, and perhaps the best males are those who spend more time preening and protecting their plumage.”
The paper’s other co-author is Colby Neuman, Cornell B.S. ‘05. In early September, Safran began a new position as a postdoctoral researcher at Princeton University. Supporters of the study included the National Science Foundation, the American Association of University Women, the American Ornithologists’ Union and the Animal Behavior Society.
March 23rd, 2006
Berkeley Dayly Planet
By JOE EATON Special to the Planet
You can hear it over the traffic on Shattuck Avenue: a high-pitched chittering, coming from somewhere overhead. Looking up, you may be able to spot a couple of small, torpedo-shaped black-and-white birds with an elegant Art Deco look, looping through the air above the downtown buildings. They’re white-throated swifts, foraging the urban canyons for airborne insects.
Swifts are odd birds. Although they have a superficial resemblance to swallows, hummingbirds are their closest relatives (the fossil record suggests hummers had swift-like ancestors). They’re built for speed, with cylindrical bodies and long, narrow wings like miniature sailplanes. They have short legs and pamprodactyl feet, the first and fourth toes capable of pivoting either forward or backward—a good design for clinging to vertical surfaces, like cave walls or cliffs.
I’ve wondered for years where the downtown swifts built their nests and only recently learned that they use the building across the street from the main library. Like most swifts, white-throats construct shelf-like structures of moss, grass, and feathers, glued together with saliva. Some of their relatives, like the edible-nest swiftlet of Southeast Asia and Indonesia, have nests that are almost pure congealed spit, the active ingredient of bird’s-nest soup. Unregulated harvesting of the nests—mostly in hard-to-reach sea caves, although one flock reportedly uses the roof of a Chinese restaurant—has caused drastic population declines in that species.
Although it’s a relatively common bird, the white-throated swift hasn’t had much attention from ornithologists. We do know that it’s highly social, nesting in colonies and sometimes gathering in flocks of over a thousand. We know that it’s migratory in part of its range, and that—again, like some hummingbirds—it can enter a torpid state when temperatures drop. We know the swift is an insect-eater, sustained by “aerial plankton” that includes both flying insects and others that drift passively on the wind. White-throated swifts have been seen following a combine harvester and scarfing the insects flushed by the machine.
But there have been few descriptions of the bird’s social behavior. Thomas Ryan and Charles Collins of California State University, Long Beach have filled some of that gap with a recent series of articles in Western Birds. Ryan and Collins observed flocks of white-throated swifts at two Southern California sites, near San Juan Capistrano and Rancho Palos Verdes, monitoring their activity patterns: arrivals at and departures from their overnight roosts. Collins, with other researchers, also intercepted the food parent swifts brought their young and analyzed the contents—mostly flies and true bugs, with a smattering of weevils and the occasional spider or silverfish. (The less common black swift was found to specialize in flying ants, a patchy but rich food source).
Back to behavior, though: Ryan and Collins describe several characteristic things white-throated swifts do, including the Courtship Fall, the Screaming Party, and the Silent Dread. “Courtship Fall” makes me think of a Butch Hancock song:
Fools fall in love
Wise men they fall too
Wise men hit the bottom
Fools just fall on through
I’ve seen Courtship Falls myself, down at Pinnacles National Monument, and they’re pretty spectacular. Here’s W. Leon Dawson, from the 1920s: “The birds come together from opposite directions, engage with the axes of their bodies held at a decided angle laterally, and begin to tumble slowly downward, turning over and over the while for several seconds, or until earth impends, whereupon they separate without further ado.” They’ve been known to plummet for 500 feet. Mating likely takes place during these falls, although it’s also been observed at the nest site.
Screaming Parties involve large groups of swifts flying past a roost site or nesting colony, all yelling their heads off. Other birds may emerge from the roost to join them. Then they break and go back to foraging. Ryan and Collins don’t provide a context for the behavior, but I have to wonder if it’s anything like the flock screams Mark Bittner has seen the cherry-headed conures of Telegraph Hill perform. Maybe it’s just avian exuberance.
Silent Dreads: Who among us hasn’t experienced those? In a Silent Dread, a group of swifts “stops calling and…departs in an uncoordinated rush, regrouping at a substantial distance from the previous center of activity.” They sometimes take place when a credible predator, a peregrine falcon or Cooper’s hawk, is nearby, although never during an actual attack. There’s a higher frequency of Silent Dreads near or after sunset, just before a flock of swifts re-enters a night roost. A swift sees something in the fading light that could be a stooping falcon and somehow, silently, communicates its panic to the whole flock.
Are these false alarms adaptive? A bird that lives such a high-velocity existence has to be able to react quickly—when a cliff looms up in the fog, when a peregrine comes at you at 200 miles an hour. That may be worth an occasional bout of the gratuitous jitters.
March 22nd, 2006
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