Loose Feathers #233

Snow Geese at Forsythe NWR / USFWS Photo

Birds and birding news

• A California Condor egg hatched at Pinnacles National Monument for the first time in 100 years. The nest is visible from the High Peaks Trail – after a mere two-mile hike and 1100-foot rise in elevation from the parking area.
• Animals like birds increase plant growth by eating invertebrates that otherwise would eat plants. A study calculated that birds, bats, and lizards reduced plant damage by 40% and increased plant mass by 14%. 
• Bowerbirds learn the calls they mimic by listening to other species rather than other bowerbirds.
• Vultures in the Everglades have been tearing off rubber car parts such as windshield wipers and sunroof seals.
• When choosing a mate, female hummingbirds value a quality breeding territory over a spectacular courtship display.
• Cornell's Macauley Library of Sound contains recordings of over 9,000 animal species, all available online and free of charge. The library was named for William and Linda Macauley. Linda Macauley has recorded calls and songs for 2,668 species of birds, and her recordings are included in the library's collection.
• Ducks have a gene that allows them to host influenza without being harmed. Chickens do not have the same gene and will die if infected with the same influenza strain.
• Barnacle Geese are being tagged with satellite transmitters to trace their migration routes and altitudes. The data will provide evidence for how wind farm development would affect them.
• The Telegraph has a photo of a Reed Warbler feeding a Cuckoo chick.
• Green roofs are attractive to Black Redstarts.
• Four men in Florida have been charged with capturing Indigo Buntings, Painted Buntings, and a Northern Cardinal for the exotic pet trade. The twenty birds have been released.
• The Syncrude trail, considering the company's responsibility for the deaths of 1,600 waterbirds in one of its tailings ponds, heard testimony this week on the importance of the region around Fort McMurray for migratory waterfowl.

Birds in the blogosphere

• Brewster's Linnet: On hosting rare birds
• Prairie Ice: More Greater Sage-Grouse 
• Birding Dude: Study Time in the Field: Greater vs Lesser Scaup 
• The Thoughtful Animal: Giant Birds And Terrified Monkeys
• Stokes Birding Blog: Winter Wren
• IBRRC: Oil spill hits Australia's Great Barrier Reef
• The Drinking Bird: With friends like these...
• Archea: Peregrine Beauty: Birds of Prey
• Bird Treatment and Learning Center: Aerial courting goes awry for bald eagles

Environment and biodiversity

• According to a GAO report, the Obama administration's decision to open the Chukchi and Beaufort seas to oil drilling was based on a faulty environmental analysis.
• A new fossil turtle species (Cerrejonemys wayuunaiki) was discovered in a Colombian coal mine. Other new turtle species may be present among the fossils discovered at the site.
• The US EPA wants consumers to recycle old cell phones rather than throwing them out.
• Paul Krugman has an essay in this sunday's New York Times Magazine about the economics of climate change mitigation.
• Australia's prime minister is angry about a coal freighter that ran aground on the Great Barrier Reef and leaked oil. Authorities will begin removing the oil soon.
• Texas oil companies have donated $500,000 to a petition drive for a ballot initiative to overturn California's climate change law.
• From 1973 to 2000, the area covered by eastern forests declined by 4.1%. Principal causes include logging, suburban expansion, and mountaintop removal mining.
• Twenty major rivers and streams in the U.S. show signs of long-term warming.
• The thawing of permafrost releases nitrous oxide into the atmosphere. Nitrous oxide is considered the third most important greenhouse gas after carbon dioxide and methane.

Blog carnivals

• Carnival of the Blue #35
• Berry Go Round #26
• Circus of the Spineless #49
• Scientia Pro Publica #24a & #24b
• Festival of the Trees #46
• Carnival of Evolution #22

Bald Eagle Chicks Hatch at Philadelphia's Tinicum Refuge

Bald Eagle Nest at John Heinz NWR / Photo by Bill Buchanan (USFWS)

A pair of Bald Eagles have hatched chicks at John Heinz NWR (also known as "Tinicum") for the first time in the history of the refuge. Tinicum is the most urban refuge in the National Wildlife Refuge system, close to major highways, an international airport, and industrial sites. The presence of breeding eagles there is symbolic of the bird's resurgence across the country, even in urban areas. The Tinicum nest was one of two active eagle nests in Philadelphia this winter. The other may have failed.

Eagles' nests are in all seven of the region's suburban counties, and the urban eagles have been touted as even more dramatic proof of the species' comeback.

In 2007, a pair of eagles were discovered nesting in the Navy Yard - the first in the city in two centuries. Their nest failed then, but the next year one eaglet survived.

By 2009, they were gone - perhaps, like generations of suburbanites, to New Jersey, officials figured.

But by then the city was seeing eagle action aplenty elsewhere. Another pair built a nest near the Pennypack Creek in the Northeast, and two young survived.

Yet another nest was under construction that year at the Heinz refuge in Tinicum, but those eagles were like bumbling newlyweds, producing a clumsy, rickety nest. And there were no eggs.

This year, both pairs returned, one to Pennypack, the other to Tinicum, and laid eggs.

Perhaps the Tinicum pair learned from last year's mistakes to build a successful nest this year. The eagle family may be helping with one of the refuge's management problems.

Refuge manager Gary Stolz said the eaglets were active. He has seen them stretching their tiny wings. Better yet, they're helping out.

The refuge has had an ongoing problem with carp, an invasive fish that has turned out to be an eaglet delicacy.

"Besides being the gorgeous, magnificent birds that they are," Stolz said, "they're helping us remove problem fish and restore native species."

The nest at Tinicum is on an island, but visitors to the refuge can see it with binoculars from a safe viewing distance.

Feverish Song Sparrows

Researchers are studying how western Song Sparrows respond to infections that might cause a fever.

As anyone who has suffered from a cold or flu knows, a high temperature is an unpleasant but important side effect of the body's immune reaction when fighting off pathogens. Laboratory studies, in which the immune responses of animals could be observed in detail, have shown that these responses display significant variations.

Why doesn't every organism defend its body at the maximum possible level of intensity? New immunological theories presume that immune responses are "costly," that is they compete with other energy-consuming processes such as partner selection, territorial behaviour and reproduction. Each individual has limited resources and must, therefore, enter into compromises, so-called trade-offs. This could explain why different species with different living conditions also display variations in their immune responses.

Apparently Song Sparrows do respond with fevers, but only at night, and more vigorously in southern areas. The really cool part of the study is that they found a way to study the birds' responses while the birds were in the wild.

Jim Adelman, a doctoral student at the University of Princeton, and a staff working with Michaela Hau and Martin Wikelski at the Max Planck Institute for Ornithology in Radolfzell have now succeeded in measuring fever and illness-related behavioural changes in various populations of a North American bird species living in the wild, the song sparrow (Melospiza melodia). For the tests, individual sparrows were caught in South California and in the northern state of Washington. To stimulate the immune response in a standardised way, both groups were administered a small dose of bacterial cell walls which causes fever for a limited period of around one day. A control group was left untreated. Following the administration of the injection, a small transmitter weighing approximately 0.5 grams was attached to the birds' backs and transmitted data on both their temperatures and activities over a 20-hour period.

Interestingly enough, the "injected" sparrows showed barely any increase in temperature during the day. However, during the night when, based on their natural biorhythms, birds reduce their metabolism and their temperatures by three to four degrees, clear differences emerged between the two populations: the Californian sparrows recorded a body temperature of over two degrees Celsius higher than the animals in the untreated control group of this population. As opposed to this, the temperatures of the more northern population increased by at most one degree and only during the first half of the night.

The lower fever temperatures of the northern sparrows is explained by their shorter breeding season. Since they need to devote more resources to breeding to cope with a shorter season, they may have less energy left over for producing a fever in response to infection.

Last Summer's House Wren Nests

Yesterday I cleaned out two nest boxes that were used by a pair of House Wrens last summer. (I have a Birdcam image of a wren entering one with nesting materials.) House Wrens are cavity nesters and will take advantage of artificial structures such as nest boxes or openings in buildings. Male wrens may build multiple nests, with only some being used for breeding. In this case there were at least two nests, a dummy nest and a real nest. You can see the remains of both nests above, the dummy nest in the foreground and the real nest in the background.

Above is the dummy nest in its box. House Wren nests have a base of twigs and other materials under and around the nest cup. A foundation of sticks may keep the nest cup dry even if water leaks into the cavity and collects on its floor. A male wren starts building as soon as it claims a nest site, and a female will complete the nest after mating. In the case of this dummy nest, there is only the twig foundation that a male placed in the box.

I was not able to extract the entire real nest intact because the opening in the box was too small. However, the nest cup did survive and is pictured above. A nest cup is built by a female wren and is lined with soft materials like grass and feathers. There appears to be some sort of foam and cotton-like materials in this nest. Some of the soft white materials look like spider egg sacs, which may be placed in nests to eat parasitic mites. I found feathers that I think were from a Blue Jay, a Northern Cardinal, and a Northern Mockingbird among the nesting materials.

Last summer I heard nestlings chirping in the box, but I never saw any fledglings. I found no signs of dead chicks when I extracted the contents, so I assume they all fledged safely. House Wrens should return fairly soon. They may nest here again, as House Wrens tend to return to the same sites year after year.

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Some information in this post comes from A Guide to Nests, Eggs, and Nestlings by Baicich and Harrison and the excellent Birds of North America.

British Columbia Spotted Owl Population Critically Low

Pat's Nature News contained a piece of very bad news about Northern Spotted Owls. The species is down to six wild individuals in British Columbia.

Spotted owls live up to 17 years in the wild, but they breed slowly, mating for life and producing just one or two chicks every two years. Silent hunters with excellent vision and hearing, the owls swoop through the open canopy of old-growth forests at dusk to catch wood rats, voles, mice, and squirrels. At one time, at least 500 pairs lived in B.C.’s forests, but over the past 100 years, their habitat has been so heavily logged that the owls have been unable to survive.

Spotted owls are particularly vulnerable to logging because of the way they nest and hunt. The owls don’t build nests but lay eggs in trees hollowed out by age or decay. And when a forest is cleared and prey populations decline, the birds often starve.

The B.C. government is belatedly trying to save the owls, with plans to capture two of the remaining males to breed with two single females in captivity. The government now has 10 owls in its breeding program and hopes to have 30 or 40 pairs so that 70 or so of the birds can be released back into the wilderness in the next decade. Government biologists have also been killing barred owls, which compete with the spotted owls for habitat.

As in the United States, the problem is attributed to habitat loss. Over 70% of the species's habitat throughout its range has been logged. British Columbia's population is much worse off than the one in the U.S. Pacific Northwest, where there is still a viable (if endangered) breeding population in the wild. It also appears from the linked article that the owls in B.C. lack the habitat protections afforded under the U.S. Endangered Species Act. If so, it may be difficult to restart a breeding population in appropriate habitat.