Archive for August, 2006
.oldandsold.com
NED came into my study one summer day, when 1 was trying to write a bird article, just as I made a slap at a tormenting housefly and almost upset my inkstand. “Your intention was good,” he remarked, “but you aren’t as graceful as the swallows yet in your fly-killing. But how did so many flies get in here?” “Oh, someone left the screen door open,” I replied; “that is one reason, and, since you have mentioned swallows, you remind me of another, and that is that we haven’t swallows enough to catch all these flies. If they were as common as they used to be, I don’t think there would be so many flies to bother us.” “Did they use to be very plenty?” inquired Ned. “Yes,” I said, “according to all accounts the familiar kinds were quite abundant up to about twenty years ago, when the hateful English Sparrow drove them away by fighting them or taking their nests. I remember well when I was small what lots of swallows there were around Boston, where I lived, far more than there are now. Of course I don’t mean to say that there weren’t any flies then, but there was a big colony of Barn and Eave Swallows on our next door neighbor’s barn, and with such a swarm catching flies all day about our place you couldn’t make me believe that there were not less flies than there would have been without them.”
“Don’t they catch other insects beside flies?” asked Ned, becoming evidently interested. “Yes,” I told him, “they are great on mosquitoes and about every sort of small flying insect. The Government ornithologists of the Biological Survey say that in the South swallows feed upon the dreaded boll weevil, and they are getting up a crusade to try to protect the swallows and introduce them to regions from which they have been driven out. One good method is to kill off the English Sparrows around their colonies, and also to put up suitable boxes for the kinds that use them. Of course boys ought not to disturb them, and the owners of barns where they build should welcome them, even though they make some dirt to clean up. They are well worth any trouble they may cause.”
After this little talk about swallows, Ned helped me drive out the flies so that there would be none of them on my bird article, and I went to work again in peace. Besides helping me in this swallow-like occupation of chasing flies, Ned promised to go with me that afternoon and help me photograph a nice Barn Swallows’ nest with four nearly fledged young, which were now about to leave.
It was a pretty hard proposition, Ned thought, when he saw the nest, on the projecting end of a timber inside a barn, away up under the roof where it was quite dark and almost inaccessible. However, I thought there was a way. We got a long ladder, and I climbed up on a beam which went rather near the nest. I pulled the ladder up after me and placed it across two beams. Then Ned handed me up some boards and I made a little platform on the- ladder to stand the camera and tripod upon. The camera set up on the tripod could now stand close to the nest, but it was too dark even to focus. However, I was ready for that difficulty. I had brought a good-sized mirror, and now I asked Ned to stand just outside the barn door in the strong sun-light and throw up the reflected light upon the nest. It was easy now to focus. Then I held up a smaller mirror which I carried in my pocket and had Ned throw the light on my mirror, and I in turn threw it down into the nest upon the backs of the young birds, and thus I made some successful quite short exposures. Then I brought down a young swallow, posed and photographed it outdoors, put it back into the nest, and the work was done, and well done—thanks to my valuable assistant.
Probably the Barn Swallow is the best known of the six species found in our Northern and Eastern districts —the bird with the forked tail, reddish breast and shiny blue-black upper parts. They build nests of mud and straw on beams inside barns and sheds. The settlement of North America by the white man has changed the habits of many of the birds, notably the swallows, and among them this particular kind. Its original preference was for rocky caves as a nesting site. Just once in my life have I found a nest thus situated. It was in a cave on lonely Seal Island, which lies twenty miles off the rugged coast of Maine, in Penobscot Bay.
Our Barn Swallow is such a happy, friendly bird that nearly everyone who knows it loves and admires it. We enjoy its merry twitterings as it darts about the barn, and are pleased at the grace with which this greyhound of the air doubles and turns. When we go out for a drive, it is a pretty sight to see them circle about us, catching the insects which our advance starts from the grass or weeds along the country roadside.
Perhaps next in familiarity comes the Eave or Cliff Swallow. This is the other kind which frequents the barns. I builds bottle-shaped nests of mud pellets up under the eaves, which are often clustered thickly together and partly built one upon the side of the other. In the primitive days these colonies of nests were built on cliffs, and in some parts of the West they are built there even yet. So the bird is the genuine Cliff Swallow out there, and the Eave Swallow with us. Originally there were no Cliff Swallows where there were no cliffs, but with the country’s settlement they spread nearly everywhere, and the dates are on record when they first appeared in various localities. This bird looks quite different from the Barn Swallow, and can be told by its nearly square tail, the pale reddish patch at the base of the bill and on the upper rump, and the light underparts.
I have photographed the nests by putting up a ladder under the eaves, driving my screw bolt into the side of the barn, screwing the small camera to it and making long-timed exposures, since the nests are in the shade. To get the adult birds from life, I await quietly beneath the nests on some low barn, with my reflecting camera in hand, and snap the birds as they fly to their nests. When the young are just beginning to fly they are quite tame and one can often walk up close to them with the camera.
The nests of many swallows get very lousy, like the Phoebes’, and it was owing to this that I once had a rather severe punishment for meddling with the Eave Swallows when I was a boy. I wanted some swallows’ eggs, and, after climbing up to some nests by means of a ladder, was trying to get my fingers into the narrow entrance of one of them, when down came the nest and smashed all over my bare head. In a moment I was swarming with bird lice from head to foot—and what a time I did have! It was days before I got rid of them all, and I was sore in every member from their bites and my scratching. Fortunately it was vacation time, and I was able to keep aloof from most of mankind.
Then there is the Tree Swallow, the kind with the pure white breast and glossy steel-blue back. How they used to swarm on the marshes and on the telegraph wires, when I was a boy, in August when they were getting ready to migrate ! But now their numbers seem pitifully small in comparison. Originally they nested in cavities of trees. Then, in well settled, localities, they changed to the bird boxes which kindly disposed people put up for them. But the English Sparrow came and drove them out, and now they have gone back to the hollow trees again.
Out in North Dakota, I have seen pairs of them flying in and out of hollows in low trees along the shores of rivers and lakes, and I was wishing that I had taken the time to photograph them. So it was pleasant to me to find a colony of them near my home nesting in stubs in the overflowed woodland where I have told of the woodpeckers nesting so abundantly. Some of the stubs which they had chosen stood out in pretty deep water and the holes were rather high up. I was standing on the “corduroy” roadway across the swamp and wondering how in the world I was going to work it to get some pictures, when I saw a Tree Swallow fly into a hole near the top of a low stub only about five feet from the water, the stub being only a yard out from the road. I waited two weeks or more till the young were hatched, and then with my reflecting camera and a lot of plate holders, I paid a visit to the nest. The male bird sat on a low branch of another stub, quite near the nest hole, and let me walk quietly up and snap him. He flitted to another stub and I got some more pictures of him. Meanwhile the female flew to the nest with a fly, so I sat down on the edge of the roadway partly behind a bush, with the camera on my knees, aimed at the nest. For a few minutes the birds flew about twittering, excited by my presence. But I sat still, and presently the male ventured. I snapped him as he approached the stub, and he flew back without entering. But in a moment he alighted at the entrance with a fly, and, not heeding the sound of the shutter, entered, fed the young, and emerged carrying. a sac of excrement. By this time I had changed the plate and caught him as he left. Then the female came, and they were constantly going and coming, giving me all the snapshots I wanted. Later, when the five young were about ready to leave, I took out two of them and posed them, and then put them carefully back into the hole.
One day I came out from the woods on the adjoining hill, hundreds of feet above this morass, overlooking the whole tract. It was a lovely panorama of high rolling hills, with two lakes nestling in the valley, and, aided by my strong field glass, I actually could see the old woodpecker hole in the swallow stub, and see the swallows enter and leave the cavity as they fed their young.
Still another familiar species is the Bank Swallow, the small brownish fellow that digs out burrows in gravel banks near ponds or streams. They are quite common, and a number of banks or cuts in my neighborhood each boast of a little colony of a dozen or more pairs. The birds arrive toward the end of April, and presently go to work digging their burrows, and then make trips to poultry yards to pick up feathers with which to make soft lining for the nests, that the very fragile pure-white eggs which are to be deposited may not be broken.
One day I visited a colony situated in a gravel cut, just off a main road. The burrows were not deep, and from one of them I took out a parent bird which was incubating, having previously set up my camera focused on a hole, and, placing it at the entrance, secured a snapshot before it escaped. Meanwhile I had allowed the horse to graze by the roadside unhitched, watched over by Ned. Just ahead there was a rise of ground and a turn in the road. I had not thought about the possibility of an automobile coming along, but, as luck would have it, one came just then, going at very moderate speed. Before I could get back the horse broke away from Ned, shied into the fence, and then dashed off with the shafts, leaving the rest of the vehicle hung up. The animal only ran to the next farmyard, where it stopped and was caught. The driver of the machine was a gentleman. He stopped, proffered assistance, gave his number, and so on. Though I was out a buggy, I did not sue him, as he had been so polite, and I was at fault for leaving the horse as I did. But the country roads are very narrow, and these engines put residents and visitors in the country in jeopardy of their lives. It is not only ill-mannered, but lawless and criminal for anyone to invade country roads with an automobile and not drive with the utmost care, stop when he is asked by the driver of a horse, and in every way be considerate, in view of the peril to life and limb which he is creating. Machines are impracticable in the country for at least half the year, and people living there are compelled to keep horses. Were all autoists gentlemen like this one just mentioned, people in the country would not be put to as much inconvenience and danger as at present they suffer, many, especially women and children, being afraid to drive or ride out, and thus are compelled to stay at home.
There is another swallow, similar in appearance and habits to the Bank Swallow, which is not so well known —the Rough-winged Swallow. They, are not often seen north of the Middle States and are common only in the West. At a distance they are distinguishable from the Bank Swallow mainly by being a little larger and having uniformly dark under-parts. Frequently they nest on the timbers under bridges, or in crevices of abutments, although they also nest like the Bank Swallow. Even Audubon did not distinguish them from Bank Swallows until he happened to shoot some specimens. So it will be well to watch for them among the supposed Bank Swallows, and some day we may add this rather rare bird to our list.
Some people call the Tree Swallow the Martin, but the genuine Martin is the Purple Martin, a larger species, the male of which is entirely of a dark glossy steel-blue color, the female duller, and paler below. They are beautiful and useful birds, but unfortunately are very tender, and late cold storms, combined with the attacks of the English Sparrow, have almost exterminated them in the New England States. In populated regions at present they generally breed in bird-boxes which people are glad to prepare for them. Sometimes, after prolonged cold rain storms in June, whole colonies of Martins, old and young alike, have been found dead in their nesting boxes. I never see them now except as migrants. Their original manner of nesting was in hollow trees, like the Tree Swallow. Out in the Turtle Mountains of North Dakota I once found them breeding quite plentifully in the poplar timber, and took a picture of a pair of them as they alighted on the branch of a stub near their nest cavity, an old woodpecker hole.
We have just one more bird to tell of in this chapter, the one that people persist in calling the Chimney Swallow. In general appearance and habits it is swallow-like, but in structure it is quite different, and belongs to the family called Swifts. So let us get used to calling it by its right name, Chimney Swift, and be accurate.
Its feet are so weak and cramped that it does not perch, but clings to a perpendicular surface, such as the inside of a chimney or a hollow tree, propping itself from behind with its peculiar tail, each feather of which ends in a sharp spine or spike. But in flight it is master of the situation, and well deserves its university degree of Swift. Almost ceaselessly, oftentimes by night as well as day, it is awing, tireless in pursuit of flying insects. It has been estimated that each swift flies a thousand miles every day, yet it never seems to weary.
Under primitive conditions, before the settlement of the country, the swift resorted to hollow trees for rest, shelter and nesting. But now it seldom occupies any other retreat than a chimney. In the autumn, when flocking preparatory for its migration south, I have seen assemblages of them at dusk drop into some selected chimney in a steady stream, until thousands must have been clinging to every available inch of brick inside.
They return to us about the last of April, but are late in nesting, for ordinarily the eggs are not laid till July. During June they may be seen darting over the dead tops of trees, hardly pausing an instant in their flight as they grasp and wrench off a twig. Having secured one, the bird takes it down the chimney and sticks it to the brick wall with gummy saliva, which she ejects. This is continued till the curious basket like structure has been completed, and then four or five elongated pure white eggs are laid. Many accidents occur. Rains wash down the nest, or the young fall down into the fireplace or pipe below, where they are likely to be left to starve. The brood of swifts make considerable racket, and the descent of the old birds into the chimney causes a rumbling sound like distant thunder. They drop a good deal of dirt, too, down the chimney. But they amply pay for their misdemeanors in the multitude of flies and mosquitoes which they destroy,
It is a hard matter to photograph a nest, owing to the narrowness of the chimneys. But I was fortunate in happening upon a very peculiar nesting site. A pair of swifts chose to build in a barn. Up near the top of the hayloft, near an open window, for the past three years they have stuck their curious nest to the plain board wall inside. The first year they raised but one youngster and the next season four. The third season they built the nest, but for some reason did not lay the eggs there.
I photographed this nest in the same way that I photographed the young Barn Swallows, with the help of Ned, the ladder and the mirrors. The second year I paid my visit when the young had just crawled from the nest and were clinging to the boards near it like so many bats. One flew off, but I photographed the other three, and then put one back in the nest and took a picture of it there. After that I carried one outdoors in the light and took some pictures showing in detail how they cling and brace themselves with the tail.
A pair of them build every year in one of my chimneys, and this year, for some reason, the eggs did not hatch. Ned wanted to get them as curiosities, so he made a small scoop net at the end of his butterfly net pole and succeeded in landing the nest and two out of four of the eggs;
A well-known naturalist once told me that it seemed to him that the swift in flight used its wings alternately. It would be an interesting bit of sport and scientific research combined to secure a series of flight pictures of the swift and try to find this out. I have thought that sometimes I would squat on the ridge pole by some favorably located chimney to which swifts resorted and see if I could get some pictures. Who else will try it?
August 31st, 2006
eurekalert.org/
ITHACA, N.Y. — Scientists at the Cornell Lab of Ornithology are asking the public to help monitor the impact on native birds of invasive species, such as the house sparrow, by participating in a citizen-science project called The Birdhouse Network (TBN).
In the mid-1800s, the little brown house sparrows were introduced into the United States from Europe to alleviate homesickness for the Old World and because they were believed to control insect pests. Since then, these adaptable birds have made themselves quite comfortable here — spreading their wings across all of North America in vast numbers, according to TBN project leader Tina Phillips. She says surging populations of house sparrows have resulted in fierce competition with native birds for nesting sites. According to 2003 data collected by TBN, house sparrows account for 43 percent of all competitor species (species that take over nest boxes intended for native birds). And although most nest-box (or bird-house) enthusiasts discourage nesting by house sparrows, the birds still comprise 10 percent of all reported nesting attempts when at least one egg is laid.
What effect is this having on North America’s bluebirds, swallows and other native cavity-nesting species? “We don’t know,” says Phillips. “There are no long-term studies showing the effect of competition between house sparrows and our native cavity-nesters. This is one reason why we’re asking everyone across the continent to become part of our nest-box monitoring project. The only way to get answers is to get data, which are provided most effectively by people who monitor nest boxes.”
TBN participants monitor activity inside nest boxes and keep track of data such as egg-laying dates, numbers of eggs and nestlings, and fledging dates. The participants send their observations to researchers at the Cornell Lab of Ornithology, where the data are combined with observations from across North America, to determine the annual nesting success of cavity-nesting birds. Competition with non-native species, such as house sparrows, as well as pesticide use and habitat loss resulted in a serious decline in bluebird populations in the middle of the last century. Today bluebird populations are rebounding thanks to bird enthusiasts who provide nest boxes in their yards, fields and neighborhoods. Phillips points out, however, that simply putting up nest boxes isn’t enough. In order to ensure the long-term future of native cavity-nesters, nest-box owners need to monitor and report what’s going on inside their boxes. Only then will scientists have a true picture of the current status and factors influencing breeding success of native cavity-nesting species.
One thing is known for sure: In head-to-head competition, house sparrows readily out-compete native species for nesting sites by evicting other nesting birds, destroying their eggs, killing nestlings and sometimes even killing the incubating female. Adding to the competition is the fact that once a male house sparrow establishes a territory, he remains there year-round and starts defending that territory early in the season, often preventing later-arriving species, such as bluebirds and swallows, from nesting.
House sparrows also are prolific breeders, raising up to four broods per season (compared with just one or two for bluebirds), each brood averaging four to five eggs. They are expert nest builders and rebuild nests at a rapid rate. For these reasons, TBN is collecting data for a new Nest-Box Competitor Study examining the effect of nest-box competition from invasive species on native cavity-nesting birds. Participants collect information about the competitor species using the nest box, the type of interference, if any, by monitors and the final outcome of the nesting attempt.
So far, the project has received more than 41,000 nesting records for more than 40 cavity-nesting species. Information, however, is still greatly needed for the Nest-Box Competitor Study.
Serious birders, beginners, families, classrooms, youth groups — everyone is invited to become part of TBN. A registration fee of $15 ($12 for lab members) helps offset the cost of running the project. Participants receive a packet that includes a full-color poster of cavity-nesting birds, access to private and public cavity-nesting listservs, an annual subscription to the lab’s quarterly newsletter “BirdScope,” and access to an online database where participants can submit, organize, share and store their nest-box observations. People can sign up by calling the lab toll-free at (800) 843-2473; outside the United States at 607-254-2473); or by visiting TBN’s Web site at http://www.birds.cornell.edu/birdhouse .
Nest Box Cams Peek Inside the Mysterious Lives of Cavity-Nesting Birds
Since 1999 The Birdhouse Network (TBN) has provided live images of cavity-nesting birds to viewers around the world. Using a system of Nest Box Cams — small cameras placed inside nest boxes — Internet viewers can follow such species as bluebirds, swallows, barn owls, American Kestrels and chickadees, as they build their nest, lay eggs, hatch, feed the young and much more. Developed and managed by the TBN staff, the cams have attracted nearly half a million viewers.
“The cams are a great way to get a up-close-and-personal look at what goes on inside a nest box, something that just wouldn’t be possible without the cams,” says Tina Phillips, TBN’s project leader. To get a peek or to make a donation to support the cams, visit TBN’s web site at http://www.birds.cornell.edu/birdhouse . To become a sponsor of the cams, contact Phillips at (800) 843-2473 or, if outside the United States 607-254-2473.
How to Discourage House Sparrows From Nesting
In addition to collecting data, there is more that nest-box monitors can do. The Birdhouse Network recommends several tips to discourage house sparrows from nesting. These tips include avoiding the use of filler grain, such as milo, millet or cracked corn, at bird feeder stations — all favored foods of House sparrows. Since house sparrows can be common around human habitation, TBN recommends placing nest boxes away from heavily trafficked areas. Another strategy is to plug the entrance hole of nest boxes until the desired species arrives for breeding, in the hope that house sparrows in the area have already set up housekeeping elsewhere. Since house sparrows are not federally protected, experienced monitors also often remove nests or eggs and deploy traps.
“Sometimes the best strategy for dealing with house sparrows is to not put up a box at all, especially if you aren’t willing to discourage their nesting in favor of native species,” says Phillips. She also adds that to really make a difference for the birds, becoming part of TBN and sharing observations with researchers is essential.
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The Cornell Lab of Ornithology is a membership institution interpreting and conserving the Earth’s biological diversity through research, education and citizen science focused on birds.
August 31st, 2006
hummingbird-house.com
By
Dan & Diane True
Twenty-six Black-chinned hummingbird nests were observed over a three year period by my wife, Diane, and I in Texas and New Mexico. Some nests were in trees. Nesting platforms known as Hummingbird Houses served as sites for other nests. Hummingbird Houses were installed under eaves, porch ceilings, and covered patios.
Migrating female hummingbirds follow males in spring into the United States and Canada from wintering grounds in Mexico by three to ten days. The birds come north for one purpose: to raise young, and they waste no time in getting down to business. Nest construction generally begins the day they arrive. Distended abdomens on some of the hens indicated those little birds arrived impregnated.
Top priority in a female hummingbird’s mind for nest site selection is: nest in a geographical area where temperatures are likely to remain 96 degrees F or less throughout her nesting cycle. Her reason is, she aims for an egg incubation temperature of 96 degrees. If the temperature rises above 96 and remains above that level for several hours, (or days) her eggs will “cook”, killing the embryo. This probably explains why areas where summer temperatures soar into the 100s see their arriving hummers “disappear” in May. The little birds “disappeared” because they were really only passing through on their way to cooler climate locations in our northern states and Canada. Invariably the little rascals “reappear” in late July and early August, and pause to show us their youngsters before humming on south to wintering grounds in Mexico and Central America. A few Ruby-throats don’t follow the crowd and remain behind in hotter states. These birds are often found in states with mountains high enough in altitude to experience a summer with less harsh temperatures…the Ozark’s and Appalachians, for example. (The air cools at a rate of 5.5 degrees F per 1,000 feet rise in altitude.) However, a few Ruby-throats remain at low altitudes in states that can sizzle in the summer. These hardy souls have learned a unique way to escape egg cooking temperatures.
The temperature within a stand of broadleaf trees will average 5 to 7 degrees cooler than open or urban areas. This is due to the tree’s transpiration, which provides natural, evaporative air conditioning within the tree’s umbrella. (An average oak transpires 50 gallons of water per day.) A very small population of Ruby-throats have discovered this natural phenomena and attempt to nest at altitudes where summer temperatures almost always exceed 100. In those cases nests are often found on the low branch of a broadleaf tree overhanging a body of water. Female Ruby-throats have apparently found the thin layer of cool air created by evaporation from the water’s surface. That thin layer of cool air, combined with the tree’s 5 to 7 degrees worth of cooling, creates a micro environment matching northern climates. Note that hummingbirds migrate to nesting areas where humans go to escape summer’s heat…’way north, the mountains, or a lake.
The rule for eastern states is, if you have females in June, it is likely the birds are nesting with you. No females in June says they are nesting elsewhere, and elsewhere is probably somewhere up north. (In Arizona and southern California, Anna’s hummingbirds avoid egg cooking temperatures by choosing to nest in January and February. Costa’s hummingbirds avoid the desert heat by humming up to nest in those state’s mountains.) The female’s second priority for nest location is: Find a place out of the wind.
The importance of selecting a nest site that is protected from the wind was emphasized from the experience of Jay and Carrie Hollifield of Roswell, New Mexico. Winds catapulted ten hummingbird eggs out of five nests from elm branches in their ranch yard in 1999. In Amistad, New Mexico, broken hummingbird eggs were often found on the ground by Dave Dunnigan after strong winds raked his ranch yard. 8 to 10 Black-chinned hummingbirds nest around Dunnigan’s place each year. One of his little hens was so determined to nest out of the wind she built down low, 18 inches above the ground, on a bush snuggled in the shelter of a hen house. It is probable this bird was not a first year mom, but rather an experienced mom who had suffered the consequences of high winds in a previous nesting season. This suggests hummingbirds ae capable of learning. In May of 2000, five of Dunnigan’s hummers chose to nest on Hummingbird Houses placed under his porch eaves, out of the wind. In Roswell, Hummingbird Houses are installed at the Hollifield place, however a dozen pairs of cliff swallows dominate choice nesting sites under their eaves. One of those Hummingbird Houses was even taken over by swallows.
Nests we observed were established in places providing as much wind protection as was available. They were sheltered either by an outer perimeter of trees, or by buildings. Six to twelve feet above the ground in the first row of inner branches where protection is increased from weather elements were prevalent tree locations. Trees of choice, in order of preference, were sycamore, fruitless mulberry, maple, elm, and Russian olive. Note the larger the leaf, the higher the preference.
A fork in a branch about 18 inches from its end was a repeating tree nest location. The chosen branch averaged 1/4″ in diameter…too small to support a cat, but dangerously whippy in high winds. A hen’s search image includes the coincidence of either a large leaf or a cluster of leaves three inches or less directly above the fork. She utilizes this leafy “umbrella” to protect her nest against sun and rain, and to shield her eggs and chicks from prying predator eyes.
Nest construction averaged five days. She brings materials to her site at a rate of 34 trips per hour. The little hen’s first load of material is spider webbing. She applies that material as a sticky foundation on the forked area of her nest site. Thereafter, her sequence is orderly. She airlifts plant down or other soft material in her beak and tucks it into the fork. After shaping and molding that material, she flies in another load of spider webbing. Most often she carries a glob of webbing clinging to the underside of her beak, under her throat, and down across her breast. Transfer of the webbing onto her nest is achieved by pressing her chin and breast against the nest and wiping the webbing onto her work. Stickiness of spider webbing appeared to be the only element binding the nest. Frame by frame scrutiny of video tapes revealed no sign that she used her spittle as glue. In that regard, for her little system to produce enough spittle to construct her nest seems beyond a hummingbird’s physical capacity.
Bits of camouflage followed the spider webbing and were applied to her work-in-progress. Another load of plant down was followed by spider webbing followed by a bit of camouflage, and so on. Four hours straight was usually her work schedule before she quit for the day. Some of the little hens worked mornings, others were afternoon types. Since developing eggs burdens her with extra weight throughout nest building, it made sense that she work on the nest no more than four hours per day.
Concealing her work from its beginning is probably a reason the female hummingbird camouflages her nest as she builds. One hen was so picky about hiding her work that on the sun bleached side of a branch she chose light colored camouflage material to match. On the shaded, and therefore darker side of that same branch, she camouflaged that side of the nest darker to match that side’s coloration. Such attention to detail created a nest that was camouflaged slightly differently on each side. Hummingbird House nests were camouflaged against the color of the eave, ceiling, or patio cover where the House was installed. Sometimes the hens gathered flakes of paint chips from the building and applied the chips to their nest. A male bird was never seen near a hummingbird nest. So, where is Daddy Bird during the female’s flurry of nest building activity?
Flashy gorgets transform Daddy Birds into Mr. Neon. To protect her children from predators, the female would be foolish to tolerate a male spotlighting her work during nest building, or during chick raising. In whatever ways hummingbirds communicate, after she has been impregnated, a probable reason we don’t see hummingbird males near hummingbird nests is that she has told Daddy Bird to take his brightly colored flashy suit and hum off.
Molding the nest’s wall as the nest progresses upward was done by pressing the top edge between her wing and body, as a potter shapes soft clay on a spinning vase.
Rounding the nest’s inside was done by ramming her little bottom, with tail feathers straight up, against inner walls. She tamps the nest’s floor by hanging on with one foot and stomping rapidly with her free foot. Since her weight is about that of a penny, hanging on with one foot and stomping with the other to pack the nest’s floor allows her leg muscle power to compensate for her light weight. She stops work occasionally and simply sits in her nest, as if resting. The little hens are so focused they ignore photo equipment moved in increments to as near to them as five feet. One photo revealed a unique pattern in the structure of hummingbird nests, a pattern that was previously unknown.
Backlighting a nest revealed that the lower half was thick and dense while the upper half was thin enough to let some light pass. She probably incorporates this feature so that she can adjust air circulation to maintain an egg incubation temperature of 96 degrees F, which is 5 degrees less than her normal body temperature. On cold days, she maintains egg temperature by positioning her body below the thinner, upper half of the nests walls hold warmth inside her nest. On hot days, raising her body above the thinner portion of the nest’s wall would increase air circulation and allow excess egg incubation heat to escape. These smart little birds refine this construction feature even more.
For additional precision of egg temperature control, the windward side of the upper wall is thicker than its lee side.
The “thickest” side of the upper wall invariably faces into prevailing wind patterns. That suggests she fashions the windward side of her nest to give her eggs protection against the probing fingers of a cool wind. Further, their first nests, those constructed in the relative cool of early spring, have thicker and therefore warmer upper walls than second nests built in summer. Another refinement in hummingbird nest building is that their spring nests are deeper than their summer nests. On cool days the hens snuggled down so deep inside their nests their beaks and tail aimed straight up. On warmer days they sat so high in the nest and were fully visible. The eggs in one nest were “cooked” during a record heat wave that spawned eight straight days of high temperatures ranging between 100 and 103 degrees F. Those eggs failed to hatch. Sometimes a nest was only half finished before the hen laid her first egg.
Without exception, the hens skipped one day before laying their second egg. In proportion to body weight, hummingbird eggs are the largest in the bird world. If human babies were proportional to hummer eggs, we would give birth to 25 pound babies. A long handled mechanics mirror was used to check a nest when a hen flew off to feed. Activity was watched from a distance through binoculars and a telescope. Clues that a hen was “in labor” came when she settled on her nest and alternated between wiggling and shaking a few moments. In one case we knew within ten minutes when a hen’s first egg arrived.Incubation time on each nest was 14 days with one exception…a 12 day period in Texas. (That hen was smaller, and her behavior different from other Black-chinns we observed. The hen may have been a member of the smaller sub-species of Black-chinned Dr. Bill Baltosser believes exists.) When the nest held eggs, it appeared the hen flew into and out of the nest in a way that reduced the chance of downwash from her wings blasting an egg out of her nest. In the split second during either launch or landing, she seems to tilt her wings in a way that would direct her wing downwash away from the nest’s opening. In one nest it apeared that downwash from her hovering flight ejected one egg, which crashed on the ground. The hen abandoned that nest and its remaining egg.
Chick feeding intervals averaged twenty minutes. Without exception the moms brooded their chicks through eight nights. The ninth they spent somewhere other than on the nest. Chicks at that age were feathered enough to regulate their own temperatures. The two chicks were large enough by then that their little bodies stretched the nest and filled it side to side, with their backs almost flush with the nest’s rim. This age, nine days, is the earliest observation of youngsters humming their wings.
When the chicks were 21 to 22 days old, the mother hummers began construction on a second nest while still feeding her first two nestlings. Fledge time for the chicks was commonly 23 days, however some where 24 or 25 days old before they left the nest. Individual chick fledge time is probably tied to its level of nourishment. First flights were usually no farther than the nearest branch.
While continuing to work on their second nests, the busy mom hummers located and fed the newly flying chicks through two to three days before they were on their own. While building her second nest the first egg often appeared during the time she was feeding her two fledged chicks. The common view held by most ornithologists about hummingbirds reusing an old nest is that they don’t. We found a different answer.
One tree nest was reused by a different mom hummer almost before it had time to cool from previous use. Two Hummingbird House nesting sites were reused by different moms within a day or two after the first chicks fledged. Those three nests were home to a total of 12 hummingbird chicks during one nesting season. We think these nests were reused because they were still intact and in good condition. Few hummingbird nests survive the winter months, and those that do are so dilapidated they are not reusable. However, we found several cases where a new nest was built on top of an old nest. One site had a stack of four nests, probably covering four years. One of the little hens nested a third time. Her third set of chicks were only a month old before they pointed their little beaks south and hummed with her and their siblings toward wintering grounds in Mexico.
Some nests were exquisite, woven by hens that worked with great skill. Others were less than perfect. Differences in building skills likely resulted from first time nesters being less adept at nest building than experienced moms.
Many times one female would hover a short distance from another female that was busy with nest building. The busy female invariably ran the intruder away. However, when the busy female left to gather more building material, the intruder would zip in and either steal nesting material, or hover all around the nest as if inspecting the work, possibly to gain building skills of her own. It also seemed as though an intruding female was considering a take over. In one instance, during her first day of nest building one female was building six nests simultaneously. Each was about 20 feet apart and all were on Hummingbird House platforms. During the second day she narrowed her building activity to three of the six. On the third day she cut her work down to two. On the fourth day she abandoned work on one and finished the other during her fifth day. In two other instances one female worked on two nests simultaneously before abandoning one and finishing the other.
A roadrunner raided one New Mexico tree nest, ants killed two day old chicks in another, and a Texas hailstorm destroyed another. The Hummingbird House nesting sites had no weather or predator problems.
Two nests became unattended when the mothers apparently met with unknown fates. One mom had collected fiberglass from somewhere and used the glass for lining her nest. We suspect she may have died from an overdose of fiberglass. In our determination to not disturb the nesting process, we waited two days after her disappearance to intervene. Her chicks were dead. After one full day of the other mom’s absence, we placed one of her starving orphans in an active Black-chinned nest built on a Hummingbird House, and the other orphan in an active Magnificent nest in a tree. What must have been two surprised hummingbird mothers, both accepted and fed the third chicks. The second day after these transfers, the Magnificent nest was empty and that mother not seen again. It is probable the nest was raided by a predator. Meanwhile, back at the Hummingbird House Black-chinned nest, three growing chicks soon created a space problem. The two largest chicks crowded the smaller chick outside the nest, where it hung by a tiny toenail hooked to spider webbing fourteen feet above the ground. The problem was solved by installing the orphaned chick’s “old” birth nest side by side with its new nest and putting the toe-nail-hanging chick alone back in its original nest. The mother continued to feed all three chicks and they all fledged.
Although we learned lessons from tree nests, we learned more from the Hummingbird House nests because they provided an ambiance that allowed intimate observations from the nest’s beginning to its end .
To see a hummingbird nest in action, check under the porch ceiling of County Line Barbeque in Albuquerque, New Mexico, between May 1 and August 30. Two moms nested there on Hummingbird Houses in the summer of 2000. Since hummers tend to return and breed in the area where they were raised, if both little hens survive the winter, they should return to the restaurant, along with surviving daughters in 2001. It is probable that between 3 and 6 nests will be built and occupied there in the summer of 2001. (Three hens returned and were nesting under County Line’s porch ceiling as of May 24, 2001.) The total number of nesting hummers from year to year in the restaurant’s developing hummingbird colony will depend on how many moms and their daughters survive the winters. Extra Houses are in place for additional moms. In 2002, there could be 6 to 10 hummingbirds raising chicks in nests under County Line’s porch.
Hummingbird banders have established the average life-span of female hummers to be 3 1/2 years. Average male life-span is 2 1/2. Black-chinned record longevity is 7 years.
The longest Black-chinned migration on record is that of a male banded at Sonita, Arizona, in July of 1988. In April of 1991, this little guy was recovered a few miles NNW of Manzanillo, Mexico, 930 miles south of Sonita. This was the first documented hummingbird flight linking the US and Mexico. Here’s to many more.
Happy humming.
Dan & Diane True
Authors of “Hummingbirds of North America”.
May 24, 2001 update: Observations gained so far during this 2001 nesting season have caused us to wonder:
Picture this: A hen heavy with eggs is looking for a place to build a nest. At the same time, winds are blowing hard, gyrating tree branch nest sites so violently as to make nest building difficult to impossible. Desperation, plus the urgency of eggs about to arrive forces her to build on a porch light fixture, or other device such as our Hummingbird House, neither of which is gyrating because they are protected from the wind. Picture the same situation on a day with steady rain. The urgency of eggs about to arrive forces her to search for a nest site while it is raining. Trees are wet and dripping. Again, she finds a porch light fixture, or our Hummingbird House, both of which are dry during the rain. Being smart, she builds a nest there and successfully raises her family.
We think the above may explain those occurrences when hummingbirds build their nests in “strange places”, such as under porch ceilings, under the eaves of a home, or in an open building such as a garage.
Want to know how many hummingbirds you are feeding? The Hummer Counter by Best-1 is a 32 ounce glass feeder calibrater and marked to answer that often asked question. At around $14.00 from your local bird supply store, or from the manufacture Best-1, Box 998, Poteet, TX 78065;1.800.772.3604.
Owning this feeder gives you a valuable tool in providing an accurate count of your year to yearhummingbird population…an important addition to our hummingbird information.
Please stay tuned, for further updates.
Dan & Diane True
August 31st, 2006
findarticles.com
We studied the frequency of intraspecific brood parasitism and physical transfer of eggs between nests in colonially nesting Cave Swallows (Petrochelidon fulva) and Cliff Swallows (P. pyrrhonota) in south Texas in 2001. Although the eggs of the two species look similar, frequency of brood parasitism in each species was unaffected by presence of the other species, which suggests that the parasitism we observed was largely by conspecifics. We detected brood parasitism in 4.6-5.0% of Cave Swallow nests and in 10.7-11.9% of Cliff Swallow nests. Brood parasitism was not significantly related to colony size in either species, to eventual success of the host nest, or to overall colony nesting success (a measure of environmental risk). We detected evidence of physical transfer of eggs in 0.7-2.0% of nests of these species. Cliff Swallows parasitized nests more often than Cave Swallows, but the frequencies of brood parasitism and egg transfer in the two species in south Texas appeared broadly comparable to those reported for Cliff Swallows in Nebraska, despite geographic differences in habitat, seasonality, breeding phenology, and levels of sociality between the populations. Received 28 January 2003, accepted 12 May 2004.
RESUMEN. - Estudiamos la frecuencia de parasitismo de nidada intraespecifico y de transferencia fisica de huevos en las golondrinas Petrochelidon fulva y P. pyrrhonota en el sur de Texas en 2001. A pesar de que los huevos de ambas especies son similares, la frecuencia de parasitismo en cada especie no se vio afectada por la presencia de la otra especie, lo que sugiere que en gran medida el parasitismo observado fue ocasionado por individuos coespecificos. Detectamos parasitismo de nidada en un 4.6-5.0% de los nidos de P. fulva y en un 10.7-11.9% de los nidos de P. pyrrhonota. El parasitismo de nidada no se correlaciono con el tamaño de la colonia, con el Ă©xito eventual del nido hospedero, ni con el Ă©xito de nidificatiĂłn general de la colonia (una medida de riesgo ambiental) en ninguna de las dos especies. P. pyrrhonota parasitĂł nidos con mayor frecuencia que P. fulva, pero la frecuencia de parasitismo de nidada y de transferencia de huevos en las dos especies en el sur de Texas parecen ser comparables con las frecuencias reportadas para P. pyrrhonota en Nebraska, a pesar de las diferencias geográficas en el hábitat, en la estacionalidad, en la fenologĂa de nidification y en los niveles de estructura social entre las poblaciones.AN ALTERNATIVE REPRODUCTIVE tactic in some animals is to lay eggs in nests of conspecifics and parasitize the parental effort of the hosts. Brood parasitism among conspecifics is now known for scores of bird species and some insects (Yom-Tov 1980, Andersson 1984, Rohwer and Freeman 1989, Rothstein and Robinson 1998) and, across taxa, appears to be associated especially with high fecundity (Arnold and Owens 2002). However, ecological conditions favoring parasitic laying have been investigated for only a few species, such as swallows (Brown 1984, M011er 1987, Brown and Brown 1989), bee-eaters (Emlen and Wrege 1986), coots and moorhens (Gibbons 1986, Lyon 1993, McRae 1998), starlings (Evans 1988, Romagnano et al. 1990), weavers (Jackson 1993, 1998), and waterfowl (Andersson and Eriksson 1982, Semel et al. 1988, Lank et al. 1989, Sorenson 1998, Andersson and Ahlund 2000). From those studies, it is clear that the frequency of parasitic laying varies among individuals both within and between populations of the same species.
One potential ecological determinant of conspecific brood parasitism is population density. When suitable hosts occur in high density and close proximity, such as in breeding colonies, parasitism may be a viable alternative reproductive strategy (Eadie and Fryxell 1992). Various workers have shown that in some species, conspecific brood parasitism increases with colony size or is more prevalent in larger colonies (Brown 1984, Møller 1987, Brown and Brown 1996, Lyon and Everding 1996, Hill et al. 1997), though in other species, colony size or coloniality per se has no effect (Hoogland and Sherman 1976, Lank et al. 1989, Rohwer and Freeman 1989, Davis 1998).
Colonial Cliff Swallows (Petrochdidon pyrrhonotn) show a relatively high incidence of conspecific brood parasitism (Brown and Brown 1989, 1996). In that species, brood parasitism increases with colony size and appears to be a successful reproductive strategy of high-quality individuals (Brown and Brown 1998) that involves accurate assessment of the best host nests to parasitize (Brown and Brown 1991). However, some Cliff Swallow populations have been reported to have a much lower incidence of brood parasitism (Smyth et al. 1993). Better understanding of the ecological conditions that do or do not promote brood parasitism requires comparative data, collected in similar ways, on other populations and closely related species.
The present study examines patterns of brood parasitism in a congener of the Cliff Swallow, the Cave Swallow (P. fulva), and also reports information on brood parasitism in Cliff Swallows from an area (south Texas) where that species has been little studied. We provide the first known reports of brood parasitism (including physical transfer of eggs between nests) in Cave Swallows, and we investigate how brood parasitism in both Petrochdidon swallows varies with colony size.
August 30th, 2006
.findarticles.com
Swallows keep eggs in several baskets
Call it nature’s version of a baby left on a doorstep. Biologists have discovered that adult cliff-dwelling swallows sometimes carry one of their own eggs into the nest of an unwitting neighboring swallow, and then fly away minus the egg — a sneaky maneuver called reproductive parasitism that may increase the chance of the egg’s survival.
Birdwatchers have long known about another form of reproductive parasitism whereby birds lay their eggs in the temporarily vacant nest of another bird. Some, like various species of swallows, starlings and ducks, keep the eggs within their own species, while cuckoos are known for filling the nests of birds of another feather. But this is the first time scientists have witnessed the transfer of already-laid eggs, report Yale University biologists Charles R. Brown and Mary Bomberger Brown in the Jan. 7 NATURE.
The researchers observed this transfer while studying a community of swallows in Nebraska. They monitored the birds both by sight and by recording the movements of marked eggs between nests. Transferred eggs showed up in 6 percent of the nests. But they add that their estimate of transfer frequency is “undoubtedly an underestimate.”n one instance, a swallow transferred its egg into a nearby nest under the very beak of the nest’s occupant. “A fight ensued when the intruder entered with the egg. The intruder was evicted from the nest within 10 seconds, but the egg remained in the nest,” according to the researchers. Previous studies have shown that swallows cannot recognize eggs as foreign.
The biological significance of this practice is still unknown. But the researchers suggest it is related to survival. In the general swallow community, roughly a quarter of all eggs fail to hatch. However, only 10 percent of transferred eggs failed, leading the biologists to theorize that when a swallow transfers an egg, it chooses superior incubators as the surrogate parents.
The transfer behavior may have developed in the ancestral swallow nesting grounds of cliffs and canyons, which are the site of frequent rockfalls, say the investigators. Individual swallows may protect against losing an entire clutch to a rockfall by spreading the eggs around.
But in a comment on the report, Cambridge (England) University zoologist N.B. Davies suggests that reproductive parasitism may be more a matter of avian economics. “A more likely explanation perhaps,” he says, “is that parasites increase their lifetime reproductive success by reducing the costs of parental care.”
August 30th, 2006
Daily Vidette - Aug 22 8:48 PM
Once again, the University Program Board will be sponsoring the Weekly Wednesday Lunchtime Special in The Bird’s Nest located in the Bone Student Center.
The program will feature many local artists as well as nationally touring singers and songwriters. It will take place every Wednesday from 11 AM to 1 PM and is free to the public.
Emily Villhauer, UPB advisor and specialist for programming with the dean of students office, said she is very excited about the upcoming entertainment.
“It’s a minimal program but it gives a great opportunity to showcase students and local performers,” she said.
ISU students and other local performers are invited to show off their talents at the events also.
“If students are interested in performing either for an hour or the whole two hours, they can fill out an application that’s available on the UPB website or they can stop in the UPB office and fill out an application and drop off a demo,” Villhauer said.
The first few weeks include nationally touring singer and songwriter Shevy Smith on Aug. 22 and ISU student Jason Fingh with special guest Dave Degoyeer on Aug. 30.
Smith has performed at ISU in the past and has always been a favorite among students.
“She did great,” Redbird Entertainment Committee Chair Person Kevin Parkinson said.
“She’s been here twice before. The students that attend her events really seem to enjoy her music,” Villhauer said.
The Lunchtime Special is returning for its second semester at ISU. This year the program will focus more on local performers.
“Last year we did more national artists, we did about half national and half local, and this year the students decided they wanted to really give an opportunity for local students or musicians to showcase their talents,” Villhauer said.
“Students really like the national acts so we kept two,” Parkinson said. In addition to Smith, the second national act will be Michael Warren who will be performing in December.
Fingh, who will be performing on Aug. 30, is very excited about his second appearance in The Bird’s Nest. The sophomore mathematics major played during the Lunchtime Special last spring.
He will be performing with Degoyeer who also plays guitar and sings.
“I write a lot of contemporary Christian music but I also do a lot of covers, so I’ll be doing both,” Fingh said.
The program has been very successful and seems to be a perfect fit for ISU.
“Once the new area opened upstairs with the Burger King and Pizza Hut, they put in this new lounge furniture and they built a little stage up there. It was kind of just a perfect place to do something weekly. We’ve heard of other programs at other schools that have gone really well doing a weekly showcase of student performers,” Villhauer said.
“The room is now wired for sound as well, so it’s got permanent speakers in there. It’s an easy place to move the necessary sound equipment like the mixing board. We can move that in, do this and then be out within three hours.”
Burger King and Pizza Hut are both open with normal prices throughout the events but spectators are not required to buy any food in order to watch the performers. Outside food is also welcome in the lounge.
UPB has been taking applications over the summer and will continue taking them throughout the year. They have plenty of open dates and they urge students to sign up. Their office is located on the bottom level of the Bone Student Center and their website is programboard.ilstu.edu.
August 30th, 2006
recipelink.com
No sooner do I ask for it than I find it…here it is for anyone who might want it:
Bird’s Nest Snacks
3 cups miniature marshmallows
3 tbsp. butter
2 tbsp. peanut butter
1 can (5 oz.) chow mein noodles
36 pastel jelly beans or M & M’s
12 pastel paper cupcake liners
In a heavy saucepan over low heat, cook marshmallows, butter and peanut butter until marshmallows are melted; stir until blended. Remove from heat and stir in chow mein noodles. Divide into 12 mounds on a waxed paper-lined pan.
With lightly buttered hands, quickly shape each mount into a next; make an indentation in the center. Fill nests w/ jelly beans or M&M’s. Trim 1/2″ from each cupcake liner; place nests in liners. Store in an airtight container.
Yield: 1 dozen
I’ll probably double this and add in some chocolate simply b/c I can’t resist!
Happy Easter!
August 29th, 2006
emr.cs.uiuc.edu
This stir-fried dish is served in a nest made from fried bean threads. Don’t hesitate to try it - it’s not very difficult, but it tends to be messy, so organize your cooking area, and clean the splashed oil as quickly as possible. It’s well worth the extra trouble. I like to serve this with a Vegetarian Spring Roll appetizer and some fresh oranges and banana slices for dessert.
Ingredients (Beef in Marinade)
• 4 T. soy sauce
• 1/2 tsp. sugar
• 2.5 tsp. cornstarch
• 2 tsp. corn or peanut oil
• 1 pound lean, high-quality beef, sliced very, very, thinly
Ingredients (Broccoli, Nest, and Stir-fry)
• 1 ounce bean threads
• 3-4 cups fresh canola oil
• 1 1/2 pounds broccoli or broccolini
• additional stir-frying oil
• 1 tsp. coarse kosher salt
• 1/2 tsp. sugar
• 1 T. Chinese rice wine
• 3 T. water
• 1-2 tsp. finely minced fresh ginger
• 1/8-1/4 dried red chili flakes
• 2 T. water
Preparation
Mix the beef marinade ingredients and slice the beef. Stir together and put in the refrigerator several hours or up to a day or if you are in a hurry, leave 1 hour at room temperature. I use either a very sharp chef’s knife to slice the beef, or I use the food processor fitted with the 3 mm. slicing blade (be sure the beef is nearly frozen). Cut the noodles into 3-4 inch pieces by putting them into a paper bag and cutting them with a sharp kitchen shears. Fry the noodle nest by heating 3-4 cups oil in a deep pot or wok, adding the bean thread pieces all at once. They will immediately explode into a white “nest.” Turn the nest over in the oil to briefly cook the second side. Remove immediately and drain on paper towels. Cut the broccoli flowerets in half. Peel the broccoli stems and slice thinly.
Stir-frying
Loosen beef slices in marinade. Prepare a serving platter (choose pleasing colors, and arrange the noodle nest in the middle). Heat a wok until hot enough to evaporate a bead of water. Add 3 T. oil; coat pan. Stir-fry broccoli for 30 seconds. Sprinkle with salt and sugar, toss to coat. Sprinkle wine in pan, wait a second or two, and add water. Stir to coat, raise the heat to simmer, cover pan, and cook 3-4 minutes. Raise heat to evaporate water, and remove broccoli to bowl to keep warm. Wipe the wok clean. Return the wok to high heat. Add 3 T. oil, and heat until hot enough to sizzle one speck of ginger. Add ginger and chili, and cook 10 seconds. Add beef, toss quickly. When beef is nearly done, add water, stir, and remove from heat.
Serving
Distribute broccoli on nest, arranging flowerets to face outwards. Mound beef in center of broccoli. Leftover beef and broccoli are good, but discard leftover noodles. Serves 4.
August 29th, 2006
cerc.usgs.gov
Over the last five years the Brazos Field Research Station research with swallows along the Rio Grande has resulted in the following four projects:
• Cave and Cliff Swallows as Indicators of Exposure and Effects of Environmental Contaminants on Birds from the Rio Grande, Texas (1999-2001) Master’s Thesis by: Daniel Musquiz, Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX, 77843-2258.
Cave (Petrochelidon fulva) and cliff swallows (P. pyrrhonota) were collected during 1999 and 2000 along the Texas segment of the Rio Grande and were used as potential indicators of local environmental contamination. Cave and cliff swallows were obtained from 8 sites along the Rio Grande from Brownsville to El Paso, Texas, and 1 reference site in Burleson County, 320 miles north of the nearest site on the Rio Grande. Blood samples were analyzed for variations in DNA content by flow cytometry, a technique that allows the detection of DNA damage in blood or other tissues. Plasma samples were analyzed for thyroid hormone (T3 and T4) levels using a radioimmunoassay technique. There were no sex-related differences in chromosome damage in both cliff and cave swallows. Cave swallows from the Del Rio area had the highest levels of DNA variation, which may be indicative of DNA damage. PAHs may have been a potential source for DNA damage; however previous studies indicate that sediment samples from tributaries near Del Rio have had the second highest chromium levels compared to other sites along the Rio Grande. Cliff swallows from El Paso had the highest levels of DNA variation, probably due to historic exposure to trace metals and possibly PAHs, while the reference site near Somerville had the lowest. T3 levels in birds from Llano Grande Lake were 3-fold higher between sampling years, while the neighboring site in Pharr-San Juan maintained identical levels. The only sex-related differences in thyroid hormone levels were found in El Paso birds, where female cave swallows exhibited higher levels of T3 hormones, and cliff swallows had higher levels of T3:T4 ratios. The causes for these results are currently unknown and merit further investigation. These data were also useful in establishing baseline data and evaluating several patterns that were evident from flow cytometry results. Areas of concern based on hormone and genetic data obtained in this study include Brownsville, Llano Grande Lake, Pharr-San Juan, Del Rio, and El Paso.
• Regional Variation and Relationships between DDE and Selenium and Stable Isotopes in Swallows Nesting along the Rio Grande and one Reference Site, Texas, USA Manuscript to be submitted to “Isotopes in Environmental and Health Studies”
Collaborators: Thomas W. Boutton, Department of Rangeland Ecology and Management, Texas A&M University, College Station, Texas.
Daniel Musquiz, Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX.
Cave and cliff swallows were collected during 1999 and 2000 from eight locations along the Rio Grande (same swallows collected in previous study) to determine if δ15N and δ13C values could be used to predict DDE and Se contaminant burdens in insectivorous birds nesting across a geographic gradient in the Texas-Mexico border and to discern if stable isotopes could help discriminate between local versus non-local acquisition of contaminants. We analyzed δ15N and δ13C in liver and muscle, and DDE and Se in swallow carcasses. Within individuals, δ15N was higher in liver than in muscle of both species by an average of 1.34 ‰, whereas δ13C was 0.145 ‰ higher in muscle than in liver. Significant differences occurred among locations in δ15N and δ13C values in liver and muscle of both species. Cave swallows from three locations in the lower Rio Grande Valley were more enriched in δ15N than swallows from other sites. In general, swallows nesting in more northern latitudes along the Rio Grande had lower δ15N and δ13C values than those nesting farther south. Concentrations of DDE were significantly greater in swallows from El Paso, Llano Grande, and Pharr than in those from Brownsville, Falcon Lake, Laredo, Del Rio, and a reference site outside the Rio Grande. All swallows (N=21) from El Paso, Llano Grande and Pharr had DDE concentrations ≥ 3 µg/g ww, a value three times greater than the estimated threshold in avian prey that could cause potential reproductive failures in raptors. Concentrations of Se also were significantly greater in El Paso and Del Rio than at other locations. Most Se concentrations were not of concern for direct effects on birds or their predators. Principal component analysis indicated some positive correlations between δ15N and δ13C values in tissues and contaminant concentrations in carcass; however, analysis of covariance suggested a stronger effect of location on concentrations of DDE and Se. At the local level (Llano Grande and Pharr) there was a significant positive correlation between δ15N in liver and DDE concentrations in swallow carcasses; however, Se concentrations were not significantly correlated with isotopes even at the local level. Our results provide a good database of δ15N and δ13C values for insectivorous birds nesting along the Rio Grande. Similar ecologies for cave and cliff swallows and their abundance and wide distribution along the Rio Grande, make them ideal indicators of environmental pollution of this portion of the U.S.-Mexico border.
•
Biomarkers and Environmental Contaminants in Swallows Nesting along the Rio Grande and a Reference Site, Texas, USAÂ Â This is a manuscript that contains some data from the previous thesis above but also inorganic and organic data and cholinesterase measurements in brain.
Collaborators: Daniel Musquiz2, John W. Bickham2, Duncan S. MacKenzie3 Michael Hooper4, Judi Sabo4, and Cole Matson2 2 Department of Wildlife and Fisheries Sciences, 2258 TAMU, Texas A&M University, College Station, Texas, 77843-2258, USA 3 Department of Biology, Texas A&M University, 3258 TAMU, College Station, Texas, 77843-3258, USA 4 The Institute of Environmental and Human Health, Texas Tech University, Lubbock, Texas
This manuscript presents information on flow cytometry, thyroid hormones, cholinesterase activity, inorganic and organic contaminants in swallows. We analyzed differences among locations and relationships between biomarkers, morphometric values and contaminants. One of the most important findings of this study is that swallows and other birds nesting along the Rio Grande east of El Paso may be impacted by contaminants as reflected by a decrease in spleen mass (relative to other locations) and significant relationships with higher concentrations of DDE and most of the metals and metalloids.
•
Environmental pollution of the Rio Grande: Are Current Pollutant Levels Affecting DNA and P-450 Aromatase Activity in Swallows? Master’s Thesis project by Megan Sitzlar, Department of Wildlife and Fisheries Sciences, 2258 TAMU, Texas A&M University, CollegeStation, Texas, 77843-2258, USA
Collaborators: Fuller Bazer, Department of Biochemistry, Texas A&M University, College Station, Texas John Bickham, Department of Wildlife and Fisheries Sciences, 2258 TAMU, Texas A&M University, College Station, Texas, 77843-2258, USA
We collected swallows in the Lower Rio Grande Valley during the 2003 breeding season. We analyzed P-450 aromatase activity in gonads and DNA damage by flow cytometry. We detected some gender and location differences in P-450 aromatase activity. The results are analyzed and writing is in progress. Master’s thesis is in preparation.
August 28th, 2006
rspb.org.uk
Swallows were traditionally cave nesters, building mud nests on ledges in caves, and even inside hollow trees. Since Neolithic times they used artificial habitats and now most nest around human habitation. The close association with people has allowed the bird to expand its range greatly through the availability of new sites.
They prefer to nest in association with domestic animals, most often in cow and pig sheds and stables. They sometimes nest under bridges, in wells and mineshafts, and even chimney stacks. They occasionally use very odd sites, including inhabited rooms and regularly moving vehicles.Â
Swallows are not truly colonial, but as nest choice primarily depends on food availability, several pairs can nest close together in loose groups, although single nests are most common.
Swallows return to Britain in April and May. The males return ahead of the females to claim nest sites. The main breeding season runs from April to August, when insects are most abundant, although late broods can be found still in the nest in September. During this time the birds raise two broods, sometimes three.Â
The nest is a deep bowl of mud mixed with grass and bound together with saliva, built by both birds on top of a rafter or another suitable ledge inside a building or under an overhang. The feather lining is added by the female. Building of a new nest takes about a week, but birds tend to re-use the previous years nest where possible.Â
The 4-5 eggs, white speckled with reddish brown, are laid at daily intervals, although bad weather can delay laying. The female incubates alone for 14-16 days and broods the young for the first week of their life, while they are naked and unable to maintain their own body temperature. The male shares the feeding duties until the brood is independent. In good conditions the brood will fledge at 21 days, but bad weather can slow down their development and delay the fledging.
From 70Â to 90% of eggs laid produce fledged young in a good year, although in years of cold wet weather food shortage can be a major cause of mortality. After fledging, the broods stay in family groups for another week or fortnight, when they are fed by their parents and return to the nest to roost. Fledged young from first broods often help their parents feed a second brood.Â
The autumn migration takes place in September and October. Juveniles and adults travel together and family groups sometimes stay together on migration.
Nest sites are traditional, and provided the food supply has not changed, the same nests or sites are used from one year to the next, frequently by the same two birds. Swallows breed when they are one year old, many returning to breed within 3 km of the nest they fledged from most birds within 30 km. They are short-lived birds, and most live fewer than four years. The maximum recorded age is 16 years.
August 25th, 2006
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