Bald eagles have found themselves a new home: Suburbia

SEPTEMBER 23, 2019

by Louis Sahagun

For much of the spring, a constant flow of people arrived at a dirt pullout on a mountain road a few miles above Azusa, each craving a glimpse of 10-pound celebrities with 7-foot wingspans and the charisma that politicians can only dream of.

These were bald eagles, after all, the bird that spreads its wings on every dollar bill and U.S. passport. And their nest atop a pine tree overlooking a reservoir on one side and Highway 39 on the other offered a full picture of home life for these majestic raptors. It was the first time bald eagles had nested in this part of the San Gabriel Mountains in 70 years.

Voices oh-wowed. Cameras clicked. Faces smiled, and photos and video footage immediately spread on Facebook and Instagram of two energetic fledglings braving their first flights out of the brown bundle of sticks, and shrieking like high-pitched, neighing horses when their parents returned with fresh fish for dinner.

The fledglings and their watchful parents are part of a new breed of "urban eagles" moving into Southern California and throughout the nation, displaying an unusual tolerance for the clatter and commotion of city life.

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City lights setting traps for migrating birds

19th January 2018

University of Delaware study looks at how birds are drawn to artificial light pollution in urban areas

UNIVERSITY OF DELAWARE

On their fall migration south in the Northern Hemisphere, scores of birds are being lured by artificial light pollution into urban areas that may be an ecological trap, according to the University of Delaware's Jeff Buler.

Buler, associate professor in UD's Department of Entomology and Wildlife Ecology, and his research team used 16 weather surveillance radars from the northeastern United States over a seven-year period to map the distributions of migratory birds during their fall stopovers. The research is published in the scientific journal Ecology Letters.

Since most of the birds that migrate in the U.S. are nocturnal and leave their stopover sites at night, Buler and his research group took snapshots of the birds as they departed.

"Shortly after sunset, at around civil twilight, they all take off in these well-synchronized flights that show up as a sudden bloom of reflectivity on the radar," Buler said. "We take a snapshot of that, which allows us to map out where they were on the ground and at what densities. It basically gives us a picture of their distributions on the ground."

The researchers were interested in seeing what factors shape the birds' distributions and why they occur in certain areas.

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Restoration of iconic native bird causes problems in urban areas

After a century-long absence, kaka were successfully reintroduced in Wellington in 2002 - but the restoration of the iconic native bird has ruffled a few feathers.

Kaka are a delight, says Victoria ecologist Associate Professor Wayne Linklater. "They're wonderful birds to watch and listen to, and you watch kids' faces light up around them." But, just like their cousins the kea, kaka are boisterous, brainy and also potentially problematic in urban areas.

An emerging challenge in Wellington's suburbs is kaka damaging property - gouging into trees, roofs and buildings.

"Kaka are cavity nesters and, like most birds, attract in numbers where there is food," explains Wayne. "They're quite happy living in cities, where there are human-made cavities and food everywhere."

This has led to neighbours arguing about whether people should be feeding kaka, says Wayne. "Wellingtonians love feeding birds and connecting with wildlife - somewhere between 25 and 40 percent of residents at least occasionally feed birds in their backyard. It extends from throwing out some scrap food to placing large quantities in bird feeders.

"It could be that for many kaka their primary food source is people's backyards, and this is driving them to gather in particularly large numbers in some neighbourhoods."

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In the urban jungle, birds rule the roosts

AMY SMART / TIMES COLONIST 

JUNE 13, 2015 06:00 AM

When Jacqueline Davis noticed an osprey building its home atop a 16-bulb light standard beaming down on Royal Athletic Park, she envisioned slow-cooked eggs or a nest turned to kindling.

The nest has become an attraction for North Park residents, who sometimes wander into the adjacent parking lot with binoculars.

But Davis’s new avian neighbours should be fine, says a wildlife expert.

Many urban birds make homes in unusual places.

“There are lots of animals that have adapted to the urban area,” said Kari Marks, manager of B.C. SPCA’s WildARC program.

Marks said “cavity nesters” are the most common: starlings, house sparrows and wrens that make homes in nooks and crannies in buildings. But bats and owls have also been known to settle down in human-made structures.

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Urban gulls found to favour fast food

Black-headed Gulls in urban environments are better at responding to human foods than their rural counterparts, shows new research in Bird Study, the Journal of the British Trust for Ornithology.

Researchers at the University of Liverpool used white bread and fresh sprats as examples of ‘anthropogenic’ and ‘natural’ food sources, to demonstrate that the preference for human food increases with the level of urban development.

Across the 11 study sites on the Merseyside coastline, the selection of natural food decreased from 80% of trials at the most rural site at Banks to 5% at the most urban site at Crosby indicating that Black-headed Gulls prefer the food types most likely to be found in their immediate environment.

Black-headed Gulls became quicker at responding to the foods supplied by the researchers during the course of the study further demonstrating that gulls can adapt to human activity. Urban birds were more tolerant of humans to begin with, allowing these city slickers to take advantage of ‘fast food’ more quickly than their country cousins.

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Light at Night, Melatonin and Bird Behavior

Oct. 2, 2013 — Low light levels, similar to those found in urban areas at night, can have a significant effect on melatonin production in birds at night. This suggests that melatonin could be mediating changes in bird behaviour at night. Reporting in BioMed Central's open access journal Frontiers in Zoology, the researchers suggest that altered melatonin production may cause birds to interpret increased light during the night as shorter nights.

Although the use of artificial light at night has had a broad range of positive benefits for human life, it has also shown to have negative impacts on certain behaviours and physiological processes in humans and animals. However, the research into the mechanisms behind the effects that increased light at night can have on wild animal populations remains limited.

In birds, light at night has resulted in a range of bird behaviour changes, including earlier activity in the mornings and changes in breeding patterns. It has been suggested that this may be due to an inability to detect how long days are, but the mechanism behind this is unknown. As melatonin has a significant role in the daily and seasonal cycles of behaviour and physiology, researchers tested how it was affected by artificial light levels in European blackbirds. To this end, the scientists exposed birds to low intensity light-at-night and looked at whether this altered the nocturnal production of melatonin and activity compared to birds that were exposed to near darkness at night.

Daily patterns of melatonin concentrations were decreased by low intensity light-at-night in both summer and winter. Combined with the observations of altered activity during the night, the group suggested that the light-induced decreases in melatonin production could result in an altered perception of day length, resulting in the birds behaving as if they were exposed to longer days when compared to birds kept under dark nights.

"Our findings may have important implications for understanding the control of seasonal processes, such as reproduction, in urbanized birds," said Davide Dominoni of Max Planck Institute for Ornithology and lead author of this paper.

http://www.sciencedaily.com/releases/2013/10/131002212206.htm