‘Divide and rule’—raven politics

 Cognitive biologists now revealed that ravens use a "divide and rule" strategy in dealing with the bonds of conspecifics. Credit: Jorg Massen

Cognitive biologists now revealed that ravens use a “divide and rule” strategy in dealing with the bonds of conspecifics. Credit: Jorg Massen

Mythology has attributed many supernatural features to ravens. Studies on the cognitive abilities of ravens have indeed revealed that they are exceptionally intelligent. Ravens live in complex social groups and they can gain power by building social bonds that function as alliances. Cognitive biologists of the University of Vienna now revealed that ravens use a ‘divide and rule’ strategy in dealing with the bonds of conspecifics: Socially well integrated ravens prevent others from building new alliances by breaking up their bonding attempts.

Thomas Bugnyar and his team have been studying the behavior of approximately 300 wild ravens in the Northern Austrian Alps for years. They observed that ravens slowly build alliances through affiliative interactions such as grooming and playing. However, they also observed that these affiliative interactions were regularly interrupted by a third individual. Although in about 50 % of the cases these interventions were successful and broke up the two affiliating ravens, intervening can be potentially risky when the two affiliating ravens team up and chase away the intervening individual. Continue reading

Escape from an evolutionary cul-de-sac

 Credit: R. Nussbaumer

Credit: R. Nussbaumer

Passion flowers with long nectar tubes depend entirely on the sword-billed hummingbird for pollination. However, as a new study by LMU researchers shows, the evolution of even such extreme specialization is by no means irreversible.

The blossoms produced by the many species of passion flowers belong to the most visually striking and attractive flowers known in the plant kingdom. Among the characteristic features of the flowers of the Tacsonia subgroup of the genus Passiflora are their extremely elongated nectar tubes. As a result, pollination in this group is wholly dependent on a single species of bird – the sword-billed hummingbird Ensifera ensifera. With its approximately 11-cm bill, which harbors a correspondingly long tongue, Ensifera is the only species of hummingbird that is capable of reaching and sampling the nectar at the bottom of the passion flowers’ 6- to 14-cm long nectar tubes. As it does so, the bird’s head inevitably comes into contact with the pollen grains, transports these to the next passion flower and pollinates it. Because passion flowers are incapable of self-pollination, this is the only means of pollination available to them. Continue reading

Avian expert warns migratory birds are facing annihilation

Millions of migratory birds that fly tens of thousands of kilometres between their homes in Australia and Siberia are facing annihilation as development destroys the vital feeding grounds they rely on during their epic journeys, a Deakin University avian expert has warned.

Director of Deakin’s Centre for Integrative Ecology Professor Marcel Klaassen has joined a growing chorus of leading scientists alarmed by a sudden and dramatic drop in the number of shorebirds finally arriving in Australia after their legendary flights across the globe. Continue reading

Research identifies drivers of rich bird biodiversity in Neotropics

 Scarlet Macaws are native to Central and northern South America. Various bird sanctuaries exist in Belize, such as the Crooked Tree Wildlife Sanctuary. Credit: Wikipedia/CC BY-SA 2.0

Scarlet Macaws are native to Central and northern South America. Various bird sanctuaries exist in Belize, such as the Crooked Tree Wildlife Sanctuary. Credit: Wikipedia/CC BY-SA 2.0

An international team of researchers is challenging a commonly held view that explains how so many species of birds came to inhabit the Neotropics, an area rich in rain forest that extends from Mexico to the southernmost tip of South America. The new research, published today in the journal Nature, suggests that tropical bird speciation is not directly linked to geological and climate changes, as traditionally thought, but is driven by movements of birds across physical barriers such as mountains and rivers that occur long after those landscapes’ geological origins. Continue reading

Migrating birds sprint in spring, but take things easy in autumn

 Radar station in Falsterbo, Sweden, for tracking migrating birds. Credit: Cecilia Nilsson

Radar station in Falsterbo, Sweden, for tracking migrating birds. Credit: Cecilia Nilsson

Passerine birds, also known as perching birds, that migrate by night tend to fly faster in spring than they do in autumn to reach their destinations. This seasonal difference in flight speed is especially noticeable among birds that only make short migratory flights, says researcher Cecilia Nilsson of Lund University in Sweden, in Springer’s journal Behavioral Ecology and Sociobiology.

Nilsson, in a group led by professor Thomas Alerstam, used a tracking radar to measure over three years the speed by which birds flew over Falsterbo Peninsula, a bird migratory hot spot in south-western Sweden. The seasonal differences they found correspond with those recorded for other nocturnal passerine migrants at other sites in southern and northern Sweden. Continue reading

Nighttime Lights Reset Birds Internal Clocks

Researchers at the University of Memphis have documented hormonal changes in western scrub-jays that could interfere with reproduction.

Researchers at the University of Memphis have documented hormonal changes in western scrub-jays that could interfere with reproduction.

Streetlights and the light from shopping centers, stadiums, and houses turn night into day, a “loss of night” that is shifting the internal clocks of birds worldwide. Now, scientists are trying to understand how artificial lights are affecting birds’ songs, mating, and reproduction.

High on bluffs overlooking the Pacific, Dominik Mosur was strolling along at 2 a.m. searching for owls. Darkness enveloped the Presidio, a historic military encampment turned national park, as Mosur made his way through cypress-scented fog. Continue reading