Antioxidant-rich diet reduces stress response during bird migration

Date: June 18, 2020

Source: University of Rhode Island

A research team led by a University of Rhode Island ornithologist had birds fly in a wind tunnel to simulate migration and found that birds that consume dietary antioxidants before and during fall migration can reduce the endocrine stress response triggered by long-duration flights.

The results, published this week in the Proceedings of the Royal Society B, emphasize the importance of protecting habitat with an abundance of available berries containing antioxidants at migratory stopover sites.

"This reduction in the endocrine stress response may be a major benefit birds gain in fall by eating fruits at stopover sites during migration," said Scott McWilliams, URI professor of natural resources science, noting that many species of birds select berries containing anthocyanins, a type of dietary antioxidant present in purple-colored berries. "We know birds prefer certain berries that have lots of antioxidants."

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Urban living leads to high cholesterol... in crows

AUGUST 26, 2019

by American Ornithological Society

Crows living in urban environments with access to discarded human food have higher blood cholesterol levels than their rural cousins. Credit: Andrea Townsend

Animals that do well in urban areas tend to be the ones that learn to make use of resources such as the food humans throw away. But is our food actually good for them? A new study published in The Condor: Ornithological Applications suggests that a diet of human foods such as discarded cheeseburgers might be giving American Crows living in urban areas higher blood cholesterol levels than their rural cousins.

Hamilton College's Andrea Townsend and her colleagues sampled the blood cholesterol levels of 140 crow nestlings along an urban-to-rural gradient in California, returning to track their survival rates after they fledged. They found that the more urban the environment, the higher the blood cholesterol of the crow nestlings raised there. To directly test the effects of human food, the researchers also provided nestlings in a rural New York population with a regular supply of McDonald's cheeseburgers and compared their blood cholesterol levels with those of nearby crows who had to fend for themselves. The crows who were fed cheeseburgers ended up with higher cholesterol levels than their neighbors, similar to those of the urban crows in California.

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Poor diet contributing to Sooty Tern decline

04/02/2019

The observed population crash in a Sooty Tern colony located on Ascension Island, one of the UK Overseas Territories (UKOTs), is partly due to poor diet, research led by the University of Birmingham has found.

The findings provide fresh evidence of the fragility of marine ecosystems and lend weight to the scientific case for creating the Ascension Island Ocean Sanctuary (AIOS), set to be one of the largest fully protected reserves in the Atlantic Ocean.

The most numerous seabird of tropical waters, Sooty Tern is an abudant species. The colony on Ascension Island is the largest in the entire Atlantic Ocean. However its population has declined from several million in the middle of the last century to just a few hundred thousand today. A team based in the University's School of Biosciences believes the birds' plight is closely linked to changes in populations of predatory fish, such as tuna. The terns follow these large fish across vast expanses of ocean to feed on the small fish driven to the surface as they hunt.

The terns had been expected to benefit from conservation work carried out on the island between 2002 and 2004 by the RSPB. This involved a feral cat eradication scheme in a bid to restore nesting populations of seabird species, including the rare Ascension Frigatebird.

However, while many seabird species subsequently began to thrive, the tern population did not recover as expected and the Birmingham team, together with researchers from the University of Exeter, the Ascension Island Government Conservation Department (AIGCD) and the Army Ornithological Society (AOS), set out to find out why.

Dr Jim Reynolds, lead author on the paper, commented: "We believe that a number of factors might influence the size of the breeding population of sooty terns on the island but we wanted to understand such factors in greater detail, resulting in causal explanations of the tern population decline over the past 60 years."

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Are emperor penguins eating enough?

Scientists gauge foraging success by spying with time-lapse video

Date:  May 2, 2018

Source:  Woods Hole Oceanographic Institution

For Emperor penguins waddling around a warming Antarctic, diminishing sea ice means less fish to eat. How the diets of these tuxedoed birds will hold up in the face of climate change is a big question scientists are grappling with.

Researchers at the Woods Hole Oceanographic Institution (WHOI) have developed a way to help determine the foraging success of Emperor penguins by using time-lapse video observations relayed to scientists thousands of miles away. The new remote sensing method is described in the May 2, 2018, issue of the Journal of Applied Physics.

"Global warming may be cutting in on food availability for Emperor penguins," said Dan Zitterbart, a scientist at WHOI and co-author of the study. "And if their diets change significantly, it could have implications on the health and longevity of these animals -- which are already expected to be highly threatened or close to extinct by the end of this century. With this new approach, we now have a logistically viable way to determine the foraging success of these animals by taking images of their behavior once they return back to the colony from their foraging trips."

Read on  

Shag diet diversifies with rising sea temperatures

20/11/2017

A new study has found that sea surface temperatures have a direct impact on the diet of European Shag, highlighting problems that future climatic warming and resultant sea surface temperature increases might impose on its populations.

Long-term changes in climate are affecting the abundance, distribution and phenology (or seasonal timing of life habits) of species across all trophic levels (or discrete hierarchies in an ecosystem). Short-term climate variability is also having a profound impact on species and their interactions. Crucially, species will experience long- and short-term variation simultaneously, and both are predicted to change, yet studies tend to focus on only one of these temporal scales. Apex predators are sensitive to long-term climate-driven changes in prey populations and short-term effects of weather on prey availability, both of which could result in changes of diet.

The study investigated temporal trends and effects of long- and short-term environmental variability on chick diet composition in a North Sea population of European Shags between 1985 and 2014. The proportion of their principal prey, Lesser Sandeel, declined from 99 per cent (1985) to 51 per cent (2014), and estimated sandeel size declined from 104.5 to 92.0 mm over the same time period.

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DNA tests on albatross excrement reveal secret diet of top predator

Date:  October 18, 2017

Source:  University of Tasmania - Institute for Marine and Antarctic Studies

Summary:

A study that used DNA tests to analyse the scats of one of the world's most numerous albatrosses has revealed surprising results about the top predator's diet. DNA analysis of 1460 scats from breeding sites around the Southern Ocean has shown that the diet of black-browed albatrosses contains a much higher proportion of jellyfish than previously thought.

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House sparrow decline linked to air pollution and poor diet

City sparrows suffer from more stress than their country cousins, find Spanish researchers, especially during breeding season

Date:  October 3, 2017

Source:  Frontiers

Summary:

House sparrows are well-adapted to living in urban areas, so it is surprising their numbers have fallen significantly over the past decades. An investigation into this worrying trend finds that sparrows living in urban areas are adversely affected by pollution and poor nutrition. The study also finds the birds suffer more during the breeding season, when resources are needed to produce healthy eggs.

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Albatross feces show diet of fishery discards

New, non-intrusive way to assess seabird diet could help improve fisheries management and monitor marine biodiversity

Date:  October 4, 2017

Source:  Frontiers

Summary:

The first-ever analysis of fish DNA in albatross scat indicates a high level of interaction between seabirds and commercial fisheries. This non-invasive method could be used to assess whether fisheries are complying with discard policies. Extending the analysis to other marine predators could help monitor marine biodiversity and broader marine ecosystem changes.

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Quality, not quantity, of diet is key to health of baby birds

Date: September 21, 2016

Source: Cornell University

In a new study that upends the way ornithologists think about a young bird's diet -- but won't shock parents used to scanning the nutritional profile of their children's food -- Cornell researchers have found that when it comes to what chicks eat, quality trumps quantity.

 

In recent decades, many aerial insectivores, such as tree swallows, have undergone steep population declines. Cornell researchers have demonstrated for the first time that the fatty acid composition in the tree swallow diet plays a key role in chick health and survival rates, potentially pointing to new ways to protect fragile bird species.

"This study really reforms the way ecologists see the food of wild animals," said senior author David Winkler, professor of ecology and evolutionary biology in the College of Agriculture and Life Sciences. "From a preoccupation with how much food is available, we need to turn our eyes to what kind of food is available."

For the study, researchers manipulated the ratio of long-chain omega-3 fatty acids [the good fat present in fish oil] to short-chain omega-3 fatty acids [the good fat in flax seeds] as well as the amount of food. Chicks given diets rich in long-chain omega-3 polyunsaturated fatty acids (LCPUFA) grew faster, were in better condition, had more efficient metabolisms and had a stronger immune response compared with chicks on a low LCPUFA diet.

The researchers found that chicks had higher growth rates and better body condition when they were fed a small amount of high-quality food than if they were fed a large amount of low-quality food.

Read on

Diet affects the evolution of birds

Date:April 13, 2016

Source:Universiteit van Amsterdam (UVA)

How diet has affected the evolution of the 10,000 bird species in the world is still a mystery to evolutionary biology. A study by Daniel Kissling of the Institute for Biodiversity and Ecosystem Dynamics (UvA) and colleagues from the University of São Paulo and the University of Utah shows how diet preferences have influenced bird diversification over millions of years. The findings were published in Nature Communications.

Since the seminal work by Charles Darwin, it is know that dietary habits of birds can affect the evolution of species, such as the beak sizes of Galapagos finches. However, birds show an astonishing diversity of species and dietary adaptations, ranging from very small nectar-feeding hummingbirds to large carnivorous eagles. How such diverse dietary preferences ultimately lead to differences in diversification dynamics (i.e. the balance between speciation and extinction) of different birds has not yet been examined.

Diet dataset

The researchers compiled an impressive diet dataset of almost all bird species in the world together with a large phylogenetic tree that represent the relatedness of all bird species. Using models of trait-dependent diversification, they then showed that omnivorous bird lineages (with species that feed on many different food items) have lower rates of speciation (i.e. generating less new species) and higher rates of extinction (i.e. losing more existing species) than species which prefer specific food items such as fruits, nectar, or insects. Furthermore, the researchers also found that over deep evolutionary time birds which are specialized on a particular food item often add other food items to their diets, resulting in evolving transitions into omnivory.

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Vulture's genes help it thrive on rotting flesh

Scavenger found to have genetic traits that account for a stalwart stomach and powerful immune system that let it carry on eating carrion

By Reuters

6:29AM BST 21 Oct 2015

A Eurasian black vulture Photo: Alamy

A diet of putrid rotting flesh may not be your cup of tea, but to the cinereous vulture, found across southern Europe and Asia, it is positively delightful. This tough bird, it turns out, is genetically wired to thrive on the stuff.

Researchers on Tuesday said they have sequenced the genome of this big scavenger, also called the Eurasian black vulture, identifying genetic traits that account for a stalwart stomach and powerful immune system that let it carry on eating carrion.

They pinpointed genetic features related to gastric acid secretion that help explain this vulture's ability to digest carcasses and other features linked to its immune system defense against microbial and viral infections from decomposing flesh.

"It is known that they are all but immune to botulism and that they can happily eat the flesh of an animal coated in Bacillus anthracis that causes anthrax," said geneticist Jong Bhak of South Korea's Ulsan National Institute of Science and Technology.

"They also are known to take infected food with rabies, hog cholera and numerous other diseases that would be lethal to most other scavengers."

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Bonelli's Eagle diet reconstruction by means of isotope analysis to improve population conservation

Date:

July 8, 2014

Source:

Universidad de Barcelona

Summary:

Carbon, nitrogen and sulphur stable isotopes analysis is an effective technique to reconstruct nestling Bonelli’s Eagle diet, according to a new paper. Diet analyses are central to the study of avian trophic ecology and can be an important conservation tool. Despite the high number of studies on Bonelli's Eagle (Aquila fasciata) diet developed in Western Europe, eagle's relationship between prey consumption and vital parameters remains unknown.

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Chick Magnet? Nest Diet Has Big Impact On Attractiveness of Hihi Birds

Feb. 12, 2013 — Published February 12 by the Zoological Society of London (ZSL) and University of Cambridge, the study reveals that male hihi birds develop more colourful and attractive breeding feathers if they receive a nest diet rich in carotenoids -- natural pigments found mainly in fruit and vegetables.

Scientists looked at the effects of newborn nutrition on male plumage in the rare New Zealand hihi (Notiomystis concta) over the course of a year. The paper was published in Proceedings of The Royal Society B.

ZSL and University of Cambridge PhD student Leila Walker says: "We first hand-fed baby hihi birds either a carotenoid supplement -- natural pigments used to colour yellow, orange and red -- or a more complete dietary supplement. Then we looked at the effect this had on male breeding feather colour once those chicks had grown and moulted into their adult plumage."

All nestlings initially develop female-like plumage and fledge at around one month old. Youngsters then moult their body feathers at about four months old, during which time the males obtain their breeding features. Colourful plumage is an important factor in a bird's breeding success as it demonstrates the strong health of a bird to females.

Continued:  http://www.sciencedaily.com/releases/2013/02/130212210118.htm

On the wing: Birds eat the darndest things

Robins relish big, juicy earthworms, right? Well, how about the Elk River robin that visited a grape jelly feeder frequently this summer -- and not just for a sweet treat. He'd dunk a worm into the jelly, then gulp it down. The reader who sent this tale noted, "We enjoyed watching this epicure enjoying his gourmet meal."

We humans may have more rigid ideas about bird diets than birds themselves do. Many birds are eager learners when it comes to adding new items to their regimen. They watch each other, too, for clues about what's good to eat, which is probably how the robin caught on to the jelly. He'd seen an oriole or catbird slurping up the purple stuff and decided to try adding a condiment to his arthropod meal.

Other epicurean experimenters include some south Minneapolis crows that gathered at a back-yard picnic table for popcorn (unsalted) and fresh water. "They'd take the popcorn and either dump it into the water before eating it, or hold a kernel in their beaks and dunk it. This went on for 20 minutes and I was laughing out loud," writes a crow fan.

Continued:  http://www.startribune.com/lifestyle/homegarden/172365611.html