Tag Archives: behavioural ecology

Non-breeding ravens live in highly dynamic social groups

(Physorg; 23 march 2017)
Ravens have impressive cognitive skills when interacting with conspecifics – comparable to many primates, whose social intelligence has been related to their life in groups. An international collaboration of researchers led by Thomas Bugnyar, Professor at the Department of Cognitive Biology, University of Vienna, could uncover for the first time the group dynamics of non-breeding ravens. The results help to understand the evolution of intelligence in this species and were published in the scientific journal Scientific Reports

Several recent studies have revealed that ravens are among the most intelligent species of birds and even species in general. But which factors caused the evolution of intelligence? According to a common hypothesis life in social groups can drive brain evolution especially when individuals benefit from remembering the identity of conspecifics and the interactions with them. With such knowledge, animals can avoid conflicts with higher ranking group members or develop alliances to gain better access to resources.

Researchers around Thomas Bugnyar in Austria and colleagues in France outfitted around 30 ravens with little “backpacks,” which measured with GPS the position of the animal every hour. The devices were charged with solar power and the data were transmitted using the GSM network for mobile phones. During the last four years of data collection movements up to 160 kilometers per day were observed. In addition in Austria and Italy a total number of 332 ravens have been marked individually with colored rings and wing-tags and their presence patterns in two study sites were monitored over years.

Conclusion of the biologists…….

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Birds Evolve Their Behavior Without Changing Their Bodies: The Case of Australia’s Honeyeaters

Bar-breasted Honeyeater by Gary Knight via Birdshare

(Authors: Eliot Miller and Pat Leonard;Photo: Gary Knight; March 10, 2017)

Usually a bird’s beak offers clues to the type of food it eats. A hummingbird’s long, slender beak is great for sipping nectar. The crossbill uses its unique bill to extricate seeds from pine cones. But appearances can be deceiving—sometimes birds find ways to do very different jobs with the same equipment, according to recent research on Australian honeyeaters, published in 2016 in the journal American Naturalist.

Crisscrossing the Australian continent, Cornell Lab of Ornithology researchers Eliot Miller and Sarah Wagner compared the diet, foraging behavior, and bill shape of all 75 species of the continent’s honeyeaters. Like hummingbirds, many honeyeaters take nectar, but some species also eat insects and fruit (most honeyeaters are considerably larger than most hummers, and the two families are not closely related). In Australia’s forested habitats, honeyeater beak shapes generally reflect these species-specific dietary differences—but not in Australia’s desert interior, the researchers discovered.

Though honeyeaters originally occupied Australian rainforests millions of years ago, that habitat is now found only in a slim margin along the coast. As a result, almost half of the species of modern honeyeaters live in the desert, which now makes up a significant portion of the continent—over 50% of the landmass receives less than a foot of rain per year.

“By and large, honeyeaters that live in the desert resemble their forest relatives in diet and foraging behavior,” says Miller. “Some eat insects they pick from leaves; others sip nectar; and some feast on fruit. There’s even a group of species that forage on bare ground like little inland sandpipers.” But as far as body and bill shape go, these species show only a fraction of the diversity found in forests. The nearly three dozen desert honeyeater species are all making do with the same basic body plan they inherited millennia ago—but using it in very different ways to survive.

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Birds follow green spaces to move between feeders

(Daniel T. C. Cox, Richard Inger, Steven Hancock, Karen Anderson,
Kevin J. Gaston, 23 November 2016 ,Photo Lewis Collard)

 

The benefits of feeding stations are obvious — to the birds that visit them and the people who maintain them — but many gardens are small and separated from other yards by roads, rivers, and other barriers. In order to maximize the benefits, we need to understand how birds move between feeders.

Between June 2013 and August 2014, researchers in southern England employed radio-frequency-identification technology to find out. They equipped 452 Blue Tits and Great Tits, relatives of chickadees, with tiny transponders and placed receivers on 51 feeders. Each time a tagged bird visited a feeder, the receiver recorded the date and time as well as the identity of the bird.

The results promise to help planners looking to improve their communities. The researchers write in the journal Scientific Reports that a higher percentage of vegetation cover increased both the likelihood that birds would move between feeders and the frequency of movement. In areas where green space was highly fragmented, birds moved between feeders in vegetated corridors. Large trees and shrubs were especially important to connectivity, write the researchers, while road gaps did not prevent movement between feeders but did decrease the frequency of visits. — Julie Craves

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