Rising sea temperatures threaten survival of juvenile albatrosses

Ecologists from Woods Hole Oceanographic Institution in the US and the French National Center for Scientific Research (CNRS) studied a population of black-browed albatross at Kerguelen Island, part of the French Southern and Antarctic Lands, where 200 breeding pairs have been monitored annually since 1979.

Reaching a wingspan of 2.5 metres, Black-browed Albatrosses breed on these sub-Antarctic islands during the austral summer, laying a single egg in October that will hatch in December. The chicks fledge in late March at a size similar to that of an adult.

Climate affects this seabird species in complex ways. In this study, the researchers developed a matrix population model that takes account of the combined effects of climate variables and functional traits in order to understand the entire life cycle and how population growth may be affected in light of a changing climate. Functional traits such as body size, timing of breeding, and foraging behaviour all have an impact on demographic traits such as survival and reproduction.

They found that changes in sea surface temperature during late winter cause the biggest variations in the population growth rate, through their impact on juvenile survival during their first year at sea. The effects of climatic conditions on seabirds generally occur indirectly.

"Sea surface temperature is widely used as an indicator of food availability for marine predators because warmer temperatures usually result in lower primary productivity in marine ecosystems, ultimately reducing the availability of prey", said Dr Stéphanie Jenouvrier, a seabird ecologist at Woods Hole Oceanographic Institution.

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Genetic influence in juvenile songbird babblings

Familial differences in earliest vocal babblings of juvenile songbirds suggests possible genetic basis for variations

Date: August 18, 2016

Source: Hokkaido University

As human language and birdsong are both acquired through vocal practice, different patterns emerge among individuals. These distinctions play an important role in communication and identification. Until now, however, it was unclear how individual birds learned slightly different vocal patterns.

The research team uncovered variances in the earliest practice singing--known as "subsong"--of zebra finch juveniles, including different temporal patterns between individuals. Furthermore, these differences were found to be more pronounced among different families. Experiments also showed that differences persisted among the juvenile birds even when deafened.

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Juvenile cowbirds sneak out at night

Date: November 2, 2015

Source: University of Illinois at Urbana-Champaign

A new study explores how a young cowbird, left as an egg in the nest of a different species, grows up to know it's a cowbird and not a warbler, thrush or sparrow.

The study, published in Animal Behaviour, reveals that cowbird juveniles leave the host parents at dusk and spend their nights in nearby fields, returning just after daybreak. This behavior likely plays a role in the cowbirds' ability to avoid imprinting on their host parents.

"If I took a chickadee and I put it in a titmouse nest, the chickadee would start learning the song of the titmouse and it would actually learn the titmouse behaviors," said Matthew Louder, who conducted the study as a Ph.D. student with Illinois Natural History Survey avian ecologist Jeff Hoover and INHS biological surveys coordinator Wendy Schelsky. "And then, when it was old enough, the chickadee would prefer to mate with the titmouse, which would be an evolutionary dead end," he said.

Louder is now a postdoctoral researcher with East Carolina University in North Carolina and Hunter College in New York.

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Songbirds: Juveniles delay departure, make frequent stopovers during first migration

Date:

August 20, 2014

Source:

York University

Summary:

Juvenile songbirds on spring migration travel from overwintering sites in the tropics to breeding destinations thousands of kilometres away with no prior experience to guide them. Now, a new study has tracked these 'student pilots' on their first long-haul flight and found significant differences between the timing of juvenile migration and that of experienced adults.

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