Tag Archives: study

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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Endangered ibises benefit from joining egret flocks

(ScienceDaily, AOS; 22 March 2017)

Birds benefit from flocking together — even when they’re not of a feather. According to a new study in The Auk: Ornithological Advances, China’s endangered Crested Ibises benefit from joining forces with other, more visually-oriented bird species while searching for food.

Joining mixed-species flocks can reduce birds’ risk of predation while boosting their foraging opportunities, but it can also expose them to competition and disease, and little research has been done on what this means for birds such as ibises that rely on their sense of touch to find food. Yuanxing Ye and Changqing Ding of the Beijing Forestry University and their colleagues studied the behavior of Crested Ibises foraging with and without Little Egrets in central China’s Shaanxi Province, recording the birds’ behavior with a digital video camera to determine whether they picked up on social cues from the other species. They found that ibises in mixed-species flocks became alert to threats sooner, suggesting they felt less at risk when mingling with the more visually-oriented egrets.

Crested Ibises were once believed to be extinct in the wild, until seven birds were discovered in a remote area of China in 1981. Ye and his colleagues believe this new information about their foraging behavior could benefit ibis conservation. “Developing habitat conditions that favor mixed-species flocks may reduce the perception of risk by ibises due to the early warning effects of egrets, particularly in habitats with high levels of predation or disturbance,” according to Ye.

“Mixed-species flocks are a common occurrence in birds, but little is known about the costs and benefits of joining such groups when species differ in their foraging tactics,” adds the University of Montreal’s Guy Beauchamp, an expert on group living in birds. “In this case, ibises benefitted from joining another more visually-oriented species in that they detected threats more quickly. This study shows how detailed behavioral observations can help us understand why species forage in groups and also join other species.”

Winter sets up breeding success: study

Winter sets up breeding success: Study

(Physorg; 20 March 2017)

For migratory birds, breeding grounds are where the action is. But a new study by University of Guelph biologists is among the first to suggest that the number of songbirds breeding during spring and summer depends mostly on what happens at their wintering grounds.

The pioneering study points to potential effects of climate change and may help conservation groups better protect migratory birds, including many species whose numbers have dropped in recent years, says Brad Woodworth, a PhD student in the Department of Integrative Biology and the study’s lead author.

The paper appears today in Nature Communications. Co-authors are U of G professors Ryan Norris and Amy Newman, and researchers in Maine and Switzerland.

Most researchers spend more time studying birds during the summer breeding season, but this study looked at how conditions in summer and winter homes affected population numbers of savannah sparrows.

The Guelph team used tiny tracking devices called geolocators to follow individual birds – each weighing about as much as three loonies – during migration over thousands of kilometres to and from their wintering grounds in the southern United States.

The researchers also used data collected since the late 1980s by researchers studying the sparrows during summer breeding at the Bowdoin Scientific Station on Kent Island in New Brunswick’s Bay of Fundy.

They found that wintering ground temperatures and population density at the breeding grounds are key factors affecting how many individuals return to breed on Kent Island each spring and summer.

That’s important information for biologists hoping to understand why populations of certain migratory birds have fallen in recent years, said Norris.

“What’s prevented us from learning has been lack of knowing where these birds go and what they do after leaving the breeding grounds,” he said.

Acknowledging that breeding grounds are usually more interesting and accessible to most researchers, he said the breeding season offers only a snapshot of a creature’s annual life cycle.

“Most birds are visitors to breeding grounds. They spend two to four months, they breed and they’re out of there.”

Not surprisingly, said Woodworth, warmer wintering grounds improve overall survival and encourage higher populations. But predictions of more frequent and severe weather caused by climate change suggest that any warming benefit may be outweighed by new threats.

“Even a harsh winter storm of a few days could put populations at jeopardy,” he said.

Norris said conservation organizations looking to protect habitat, including buying land or pushing for protected status for various species, might need to focus more on wintering ground conditions. Grassland birds, for example, are increasingly threatened by more intensive farming in their winter homes.

“You can only really make effective decisions about where to put resources for conserving migratory animals if you know what’s driving year-to-year fluctuations in their populations,” said Norris, noting that the study offers a model for studying other migratory animals from caribou to whales.

“We need to know what’s happening at both the breeding and non-breeding grounds. For many species like savannah sparrows, the non-breeding grounds might matter more.”

Study reveals new insights into the dining habits of toucans

Study reveals new insights into the dining habits of toucans

(Brian Mcneill; 10 March 2017)

While Toucans’ diets consist primarily of fruit, new research co-authored by a Virginia Commonwealth University biology major suggests the bird species’ dining habits are actually more opportunistic than previously believed and include the eggs of ground-nesting birds.

Maria Vera, a student in the Department of Biology in the College of Humanities and Sciences, was part of a small team of undergraduate students and researchers who traveled to Costa Rica last summer for a nine-week National Science Foundation Research Experiences for Undergraduates program to conduct a nest predator study.

As part of the study, the team built artificial bird nests on the forest ground and monitored the fake nests with camera traps. The cameras picked up two species of toucan descending to the ground to consume the eggs, marking what the team believes may be the first report of the bird preying upon nests on the forest floor.

The findings suggest toucans may be more opportunistic eaters, particularly in disturbed or fragmented habitats where fruit trees are scarce.

The team’s study, “Toucans descend to the forest floor to consume the eggs of ground-nesting birds,” is published in the March edition of the journal Food Webs.

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New Study Supports the Rarity and Limited Range of a Kauai Endemic Bird

A little brown bird sitting on a branch
(USGS 16 March 2017)

A new study provides the first rigorous population estimate of an enigmatic endangered bird species found only on Kauai, the Puaiohi or Small Kauai Thrush: 494 birds. Scientists have long believed that the species was very rare, but it had heretofore eluded a precise count due to its secretive demeanor and the rugged, inaccessible terrain it inhabits deep in Kauai’s Alakai Plateau.

The Puaiohi was listed as Endangered in 1967, when the Endangered Species Act became law, because of its rarity and single-island residency. One of the first goals mentioned in the plan for its recovery was to estimate the size of the population. Accomplishing this goal was hampered by a lack of resources, the species’ cryptic nature and its remote habitat.

“Population estimates are a cornerstone of species conservation efforts,” said Dr. Eben Paxton of the U.S. Geological Survey, a co-author of the study. “They are the benchmark against which managers monitor the success of their conservation efforts. If managers don’t know how many individuals exist to begin with, it is impossible to tell if a population is increasing or decreasing in response to conservation activities.”

Dr. Lisa Crampton, the lead author of the study, added: “We are thrilled that we finally have accomplished this objective.”

Once found island-wide, the Puaiohi’s range and population size has been reduced by a number of threats: habitat loss and degradation, non-native predators, and introduced mosquito-borne diseases, such as avian malaria. Previous research by Kauai Forest Bird Recovery Project and its colleagues has suggested that Puaiohi are somewhat tolerant of avian malaria, and rat predation on nesting females is likely limiting the Puaiohi population’s ability to grow in size. The new study also suggests invasive weeds at lower elevation may restrict Puaiohi’s range.

Given these results, conservation efforts for this species will focus on controlling introduced predators and reversing habitat loss from degradation and invasive weeds.

“Three hundred self-resetting rodent traps have been deployed in the core of the Puaiohi’s range, thanks to funding from the successful crowdfunding campaign – #BirdsNotRats, American Bird Conservancy, National Fish and Wildlife Foundation, and US Fish and Wildlife Federation,” stated Dr. Crampton. She continued, “This study allowed us to estimate Puaiohi distribution in remote parts of the species’ range that are difficult to survey, and identify new hotspots of Puaiohi where we should implement these management activities, which will accelerate the species’ rate of recovery.”

KFBRP, USGS Pacific Island Ecosystems Research Center, Diegmann Science Services, and University of Hawaii Hilo Hawaii Cooperative Studies Unit worked together develop a special methodology to survey this cryptic bird species in this difficult environment and to use both field-collected and remoted-sensed data to generate a population estimate. KFBRP is a collaboration of the State of Hawaii’s Department of Land and Natural Resources Division of Forestry and Wildlife and the Pacific Cooperative Studies Unit at the University of Hawaii Manoa that is responsible for conducting research that aids the conservation of Kauai’s endangered forest birds

 

Wild Birds an Unlikely Source of Costly Poultry Disease

Duck with various brown colored feathers
(USGS; 15 March 2017)
Wild ducks and shorebirds do not appear to carry Newcastle disease viruses that sicken or kill poultry, according to a new study led by the U.S. Geological Survey.
Avian “paramyxovirus” viruses, which can cause Newcastle disease, are found throughout the planet, infect wild and domestic birds, and sometimes lead to disease outbreaks. In North America, previous research found that paramyxoviruses in cormorants, have occasionally been associated with bird mortality events.However, few studies have assessed virus exchange among wild waterbirds and across the landscape.
“Newcastle disease has been associated with outbreaks of disease in pet and zoo birds and is among the most economically costly poultry pathogens worldwide,” said Andy Ramey with USGS and lead author of the study.  “However, there hasn’t been a tremendous amount of research focusing on how viruses are spread among different types of wild waterbirds or within North America.”

USGS and collaborators from U.S. Southeast Poultry Research Laboratory of the U.S. Department of Agriculture, the University of Texas and the University of Georgia examined the genetic relationships of avian paramyxoviruses isolated from wild bird samples from across the U.S. to examine the evidence for exchange of viruses among different types of birds such as cormorants, ducks, shorebirds, and gulls.  The authors also examined how viruses are dispersed across the continent.

“We found new genetic diversity in these wild bird samples but nothing that suggests that ducks or shorebirds are a reservoir for viruses causing Newcastle disease or strains that are likely to be harmful to domestic poultry,” said Ramey.  The authors also found that some genetic diversity of avian paramyxoviruses appears to be widespread among different species and geographic locations whereas other viruses may be limited to certain regions or particular hosts.

The new report is entitled, “Assessment of contemporary genetic diversity and inter-taxa/inter-region exchange of avian paramyxovirus serotype 1 in wild birds sampled in North America” and is available at the website for Virology Journal.

Common Cuckoos can distinguish the calls of their neighbors from a stranger’s

(Author: Dr. Mark Hauber; Photo: Csaba Moskat; March 13, 2017)

Male cuckoos appear to have a unique call that makes them distinguishable to and from other males. A new study appearing in Animal Behaviour shows that an individual cuckoo call may determine how a male responds to an interloper in his territory—behaving more tolerantly towards neighbors and more aggressively towards strangers.

Common cuckoos, Cuculus canorus, are brood parasites: they lay their eggs in the nests of other bird species, and let these hosts incubate their eggs and feed and rear the nestlings. Although cuckoos do not show parental care, they demonstrate complex social behavior, including territoriality and male-male aggression. Cuckoos have a well-known and simple two-phrase call (“cu” and “coo”), uttered by males during the breeding season. Previous studies have suggested that the “cu-coo” call of males is individually unique, allowing discrimination between different classes of males.

Researchers in central Hungary used playback experiments in a dense population of radio-tagged cuckoos to test whether neighboring males are tolerated more than unfamiliar intruders: the classic “dear enemy” phenomenon. The birds responded more aggressively to the calls of unfamiliar simulated intruders (strangers) than to the calls of conspecifics with whom they shared territorial boundaries (familiar neighbors). Cuckoos reacted within less than half a minute on average; they often approached the loudspeaker to within 5 to 10 meters from up to 80 meters away, and used their “cu-coo” calls in response. The birds used their simple call for the discrimination of familiar and unfamiliar individuals, and did so specifically to defend their own territories. In turn, they showed tolerance to nearby conspecifics, such as neighbors with overlapping territories. Since more than one cuckoo was interested in the playbacks, this study also confirmed the opportunity for brood-parasitic birds to socialize during the breeding season.

One of the study authors, Dr. Mark Hauber, Professor of Psychology, Hunter College, and Interim University Vice Provost for Research, City University of New York (CUNY), said, “This study is exciting for two reasons—it shows that brood parasitism is not an alternative for complex social dynamics in territorial birds. Also, song learning is not required for recognizing friends from enemies.”

Future studies may examine the importance of individual call recognition, determine which parameter of the cuckoo call makes it unique, and clarify whether multiple overlapping territories, quasi “cuckoo hotspots,” are related to the presence of female cuckoos or driven by available host nests.