How Birds Cooperate to Defeat Cuckoos

Why help another when you can help yourself? Cooperation is very common in nearly all life, from genes and cells to humans and other animals. However understanding why can be difficult: being selfish seems more rewarding. In a new study published in Science, we investigated whether the evolution of cooperative breeding in birds could be linked to defending their nests.

Cooperative breeding is when three or more individuals contribute to the care of young. While this happens in many animals, it is the social system of approximately 9% of birds, and is particularly prevalent in sub-Saharan Africa and Australasia.


However, understanding why evolution drove such behaviour remains controversial. Some studies have linked its occurrence with variable and unpredictable environmental conditions, while others have linked it to stable and predictable conditions.

Lees meer: Livescience

Biparental incubation patterns in a high-Arctic breeding shorebird: how do pairs divide their duties?

Bron: Behavioral Ecology (2014) 25 (1): 152-164 doi:10.1093/beheco/art098
Auteurs: Martin Bulla, Mihai Valcu, Anne L. Rutten, Bart Kempenaers
Abstract: In biparental species, parents may be in conflict over how much they invest into their offspring. To understand this conflict, parental care needs to be accurately measured, something rarely done. Here, we quantitatively describe the outcome of parental conflict in terms of quality, amount, and timing of incubation throughout the 21-day incubation period in a population of semipalmated sandpipers (Calidris pusilla) breeding under continuous daylight in the high Arctic.

Incubation quality, measured by egg temperature and incubation constancy, showed no marked difference between the sexes. The amount of incubation, measured as length of incubation bouts, was on average 51min longer per bout for females (11.5h) than for males (10.7h), at first glance suggesting that females invested more than males. However, this difference may have been offset by sex differences in the timing of incubation; females were more often off nest during the warmer period of the day, when foraging conditions were presumably better.
Overall, the daily timing of incubation shifted over the incubation period (e.g., for female incubation from evening–night to night–morning) and over the season, but varied considerably among pairs. At one extreme, pairs shared the amount of incubation equally, but one parent always incubated during the colder part of the day; at the other extreme, pairs shifted the start of incubation bouts between days so that each parent experienced similar conditions across the incubation period.

Our results highlight how the simultaneous consideration of different aspects of care across time allows sex-specific investment to be more accurately quantified.

Rainfall to Blame for Decline in Arctic Peregrines

Rain, crucial to sustaining life on Earth, is proving deadly for young peregrine falcons in Canada's Arctic.
 
A University of Alberta study recently published in Oecologia shows that an increase in the frequency of heavy rain brought on by warmer summer temperatures is posing a threat not seenin this species since before pesticides such as DDT were banned from use in Canada in 1970.

The study is among the first to directly link rainfall to survival of wild birds in Canada.

Lees meer: ScienceDaily