nest

Engineers are Studying Birds' Nests

Debbie Blicher is Senior Producer of Talkin’ Birds.

When Talkin’ Birds Senior Producer Debbie Blicher was in fourth grade, her class was challenged to design a vehicle that would allow an egg to survive a two-story drop without cracking. She and her partner had both watched birds build nests, so they cradled their egg in loosely packed, shredded paper—a sort of spherical nest—inside a paper lunch bag (even then, Debbie recycled!). Theirs was the only egg that survived the drop.

In view of this triumph, Debbie is pleased to learn that Dr. Hunter King, a University of Akron experimental soft matter physicist and assistant professor of polymer science and biology, has received a three-year, $260,000 grant from the National Science Foundation’s (NSF) Division of Civil, Mechanical and Manufacturing Innovation to study “the collective mechanical interactions of disordered, randomly packed elastic filaments.” In other words, twigs packed together. In other, other words: birds’ nests.

Birds’ nests have to withstand weather changes, swaying trees, repeated impact from birds sitting on or entering them, and other mechanical factors—all without damaging the eggs they contain. As King puts it, “Nests are lightweight, soft, flexible and shock-absorbent, but made up of hard, durable components – properties which are ideal for packaging materials.”

In the abstract submitted to the NSF, King and his collaborators from the University of Illinois at Urbana-Champaign (Illinois) state that they’re investigating how birds’ nests hold their shape as a “result of a subtle interplay between geometry, elasticity and friction” and point out that this question has not yet been thoroughly studied.

King’s graduate assistant Nicholas Weiner is conducting a series of experiments to analyze the behavior of randomly packed filaments in response to various perturbations. The collaborators at Illinois will attempt to duplicate his findings through computer simulations

Understanding how nests work could fuel advances in civil engineering and architecture, among other disciplines—not to mention packaging.

King plans to collaborate with the Akron Zoo to set up cameras and record birds building their nests: the original engineers at work.

So the next time a kid you know is participating in the “egg drop” challenge, think of birds nests and Dr. Hunter. And who knows? Maybe the kid will grow up to get an NSF grant. (Or to be Talkin’ Birds Senior Producer.)

The Cuckoos are Coming: Alaskan Birds, Wise Up!

Debbie Blicher is Senior Producer of Ray Brown's Talkin' Birds. 

As you may know, the Common Cuckoo and Oriental Cuckoo are brood parasites. That is, they lay their eggs in the nests of other birds, leaving their chicks to be raised by the unsuspecting foster parents. A cuckoo chick in the nest reduces the likelihood that the original chicks will survive, because female cuckoos time their egg-laying so that their chicks hatch first...and then shove the other eggs out of the nest. 

In areas where brood parasites are common, host species often develop coping strategies. Some birds hide their nests, or nest at different times. Some attack the brood parasite before she lays her egg or abandon the nest once she's laid it. Others pierce the parasite's egg and toss it out of the nest.

But what about birds that live where brood parasites aren't common? A new study from the University of Illinois and the University of Tennessee, Knoxville shows that an invasion of cuckoos from eastern Russia might cause significant losses among Alaskan birds. Professors Mark Hauber and Vladimir Dinets led the study to learn what Alaskan birds do—or don't—know about coping with brood parasites.

Common Cuckoos and Oriental Cuckoos are occasionally sighted in Alaska. Most likely, they've gotten there from Beringia in eastern Russia. While there isn't solid evidence that cuckoos are breeding in Alaska, Hauber says "it's likely already occurring."

Researchers put two types of fake eggs into the nests of more than two dozen songbird species in both Siberia and Alaska. (The fake eggs resembled varieties of cuckoo eggs.) Common Cuckoos and Oriental Cuckoos have advanced into Siberia and now breed near the Bering Strait; in comparison, Alaska is new territory. The researchers made sure to test each nest with each kind of egg. After the usual losses from predation, they had data from 62 nests of 27 bird species. 

Fourteen out of 22 Siberian nesting pairs rejected the fake eggs, but only a single one of the 96 Alaskan pairs rejected the fakes. Hauber suspects this result indicates that Siberian songbirds have encountered cuckoos long enough to develop coping behaviors, but he's worried about Alaskan songbirds. "The North American hosts have no defenses against invading cuckoos. They will be parasitized."

We hope that future ornithologists will follow up to find out how the Alaskan songbird population distribution has changed—and whether any of them have wised up about cuckoos. 

Want to see the original article? Click here. 

 

 

A Lesson in Careful Tree-Cutting

When Canadian biologist Chris Fisher drove through Banff, Jasper, Mount Revelstoke and Glacier national parks in May, he noticed that many trees were being cut down along the highways for various park projects. May is prime nesting season, so he wondered how the park service was managing not to disturb birds. After all, the Migratory Birds Convention Act prohibits killing, capturing, taking and disturbing of migratory birds or their nests from late April until mid-August. Wouldn't you be curious too?

Michael den Otter, an environmental assessment specialist with Banff, Yoho and Kootenay, confirms that safety upgrades, fence maintenance, and other infrastructure improvements are indeed requiring the cutting of trees along the highways, but he says that all the national parks are following the standards. “Most of the trees you see beside the highway were actually cut before the end of April. We try whenever possible to schedule our work so we’re not going into that bird breeding season.”

Sometimes it isn’t possible to schedule work so it doesn't interfere with nesting season, for instance in places where snow doesn't melt until quite late. In those places, there's a set of rules to follow that includes extensive nest sweeps. Biologists search for nests for three days during the week before cutting is scheduled. den Otter says, “If we find any sign of nesting birds, then that project will have to either mitigate that or it will have to be put on hold until whatever happens to be nesting there moves on.”

For example, a recent sweep found a dark-eyed junco along the Trans-Canada Highway during some tree removal in Yoho National Park. den Otter says, “We put a 100-meter buffer around that nest area and we’ll have to wait to complete that work in the fall when the bird fledges." A 100-meter buffer is higher than the standard, so it sounds like these folks are serious.

den Otter says the crews haven’t encountered many nesting birds in the areas along the highways where the work is being done. After all, it's a pretty noisy and disturbed area, not the deep, dense, old-growth forest that many birds really like. Still, dark-eyed juncos and white-crowned sparrows do prefer these edge habitats, and they are plentiful—and being allowed to do their thing while the projects wait. 

Fisher, the biologist, states that Environment Canada suggests not performing any nest sweeps in forested environments. “It’s their position that the likelihood of finding every single nest or the complexity of the habitat really makes it difficult to find all of the nests." He'd prefer that the national parks not even try to remove trees until after nesting season. 

Nest-Building Lessons

Most birds build nests, but how do they know how to build them? It's not like there are published blueprints. Very little research has been done on how nest-building birds know what they know, but here's an intriguing study. 

Male Zebra Finches build circular, domed nests for their mates and chicks. New research at the University of St Andrews, Scotland, shows that Zebra Finch males learn to build these nests at least partly by watching other Zebra Finch males. However, they'll imitate only the males they know. 

Scientists in the School of Biology paired up female Zebra Finches with males who had never built a nest. Each pair watched the male of another pair build a nest; this male was either known to them or a stranger. While building, this male used pink or orange string, colors that Zebra Finches don't normally use. (How they got him to use those colors isn't explained. Our guess is they had him read a 1970's issue of Architectural Digest.)

When the time came for the newbie nest-builder to build his first nest, he used the same color string as the male who demonstrated--but only if the demonstrator was a familiar bird. If the demonstrator wasn't, then the newbie did not make the same color choice. 

The experiment showed that birds will turn to public information when they need to decide which materials to use to build their first nest, but only if they know the individual who provided the information. We think birds could teach human students a thing or two about doing research for school papers with Google. 

Dr Lauren Guillette of the School of Biology, lead of this study, suggests that birds might learn from one another in a way that resembles human beings' learning culture.  "This is called ‘social learning’, and can save time and effort for first-time nest-builders....Perhaps surprisingly, the birds did not always use this ‘advice’, especially if it came from a stranger. In humans, learning from those we know is one way that cultural traditions are formed, from the tools we use to the clothes we wear or the music we listen to.”

Want to read the original article? Find it here. 

Scrambling Eggs' Incubating Temperatures

New research indicates that climate change may affect the development of embryos in birds' eggs, especially if the birds live in a hot climate.

A team of scientists at Australia's Macquarie University studied the effects of warming atmospheric temperatures on in-the-egg development of wild Zebra Finches, Taeniopygia guttata (yes, we're discussing Zebra Finches again).    In the wild, the Zebra Finch breeds in arid and semi-arid regions throughout Australia where atmospheric temperatures regularly exceed 96.8◦F. Like all birds, Zebra Finches can lay only one egg per day. They don't start incubating them until the clutch is complete, which takes about five days.

All the eggs are incubated equally, and they tend to hatch on the same day. Why does this matter? Because the chicks who hatch first grow big first, depriving their smaller siblings of resources. 

The Australian research team suspected that warm temperatures might cause problems during the egg-laying, pre-incubation stage. If the ambient temperature were to become warm enough for eggs to develop even without an adult sitting on them, the earliest-laid eggs would hatch earliest.  They were also concerned that Zebra Finches might be reaching the upper edge of their tolerance for high temperatures--in other words, that heated eggs might not hatch at all.

To test the prediction that warmer nest temperatures trigger early development, the team set up “hot” and “cool” experimental nest chambers. Thirty-three eggs from eight clutches were removed from their parents' nests on the day they were laid and placed into one of the four chambers. They were kept cool or warm while their sibling eggs were laid, then returned to their parents, who incubated the entire clutch until hatching. 

All the experimentally treated eggs hatched following their return to the parental nest, no matter how they had been treated--that's the good news: even the "hot" eggs survived. Overall, the average developmental time was 13 days — shorter for eggs that had been placed in the “hot” nest chambers. Also, as predicted, the eggs laid early in the laying sequence developed and hatched sooner.

Now the bad news: the time to hatching was similar for eggs placed in either the natural nest chambers or in the nest-box nest chambers--just 13 days, when 14 days had been expected. In other words, even though the heat-treated eggs hatched first, ALL the nests were "hot" enough to hatch fast.

What does this mean? That the nests of birds in hot climates are already affected by climate change, and they might suffer more if temperatures increase.

Zebra Finch Pairs Seem to Discuss Child-Rearing Inequalities

Like humans, some bird species mate for life and rear chicks together. But do they squabble like we do when one partner seems to be slacking off? The answer seems to be yes.

A forthcoming article in the Biological Journal of the Linnean Society describes research on vocalizations between Zebra Finch mates (Taeniopygia guttata) when they're incubating eggs. Zebra Finch couples share all chick-rearing responsibilities, including sitting on the nest before the chicks hatch. They sit in shifts about a half-hour long; while one sits, the other goes in search of food. When it's time to change shifts, the finches have what sounds like a conversation. Researchers were curious about whether this finch-to-finch conversation would change if one spouse were late returning to the nest for his or her turn. 

Working with twelve pairs of Zebra Finches incubating eggs in a large aviary, researchers trapped the male of each pair at the beginning of a foraging shift and detained him for an entire hour. Remember, his spouse was home on the nest, expecting him to return in a half hour. She did not leave the nest while waiting. Instead, she and the male had a, um, rapid conversation when he finally returned, vocalizing at each other faster than usual. (We imagine a heated argument.)

Are you wondering whether a female took extra time away from the nest if her spouse came back late? The answer: only if the male didn't talk with her much. If the late-arriving male initiated only a short conversation, the female would fly off for up to an hour. However, if the male took the time to "talk" longer with the female, she'd come back in 30 minutes. In other words, it looked as if the female got back at the male only if both spouses did not talk long enough to sort things out. 

No word on what the unhatched chicks thought about these delayed arrivals and arguments. Perhaps a next-generation study is in order.

Spying on California Condors

Smile! These condors are on camera!  That's right: from anywhere in the world you can watch the activity in the Koford's Ridge nest at Sespe Condor Sanctuary, Los Padres National Forest, near Hopper Mountain National Wildlife Refuge. Female #111 and male #509 are the proud parents of a nestling who will be banded at the age of four months. This chick is an only child because California Condors lay just one egg per nest.

So--why nest cams? 

California Condors are critically endangered, and the Koford's Ridge nest cam project is part of the California Condor Recovery Program's effort to manage and learn more about their communities. All of the more than 400 condors now alive are descended from just 27 birds. These were brought into captivity in the early 1980s for what has turned out to be a successful captive breeding program; now the project's focus is on re-establishing these birds in the wild. 

For more info on this nest, its habitants, and the people studying them, listen to our show broadcast on Sunday, August 30, 2015. Our guest Charles Eldermire from the Cornell Lab of Ornithology gave us all the details. Click here for the link.  And remember to listen to us every week! Click How To Listen for our live stream, radio stations in your area, and an archive of all our shows. 

To check out the California Condor nest cam project, click here.