Male Eurasian jays know that their female partners’ desires can differ from their own

Knowing what another person wants is not a trivial issue, particularly when the other's desires are different from our own. The ability to disengage from our own desire to cater to someone else's wishes is thought to be a unique feature of human cognition. New research challenges this assumption.

Despite wanting something different to eat, male Eurasian jays can disengage from their own current desire in order to feed the female what she wants even when her desires are different to his.

Lees meer: ScienceDaily

Foraging site choice and diet selection of Meadow Pipits Anthus pratensis breeding on grazed salt marshes

Auteurs: van Klink Roel, Mandema Freek S., Bakker Jan P., Tinbergen Joost M.
Bron: Bird Study; Mar 2014, Vol. 61 Issue 1, p101-110, 10p
Abstract: 

Capsule Breeding Meadow Pipits foraged for caterpillars and large spiders in vegetation that was less heterogeneous than vegetation at random locations.

Aims To gain a better understanding of the foraging ecology of breeding Meadow Pipits on grazed coastal salt marshes, we tested three hypotheses: (1) there is a positive relation between vegetation height and prey abundance, (2) adult birds preferentially forage at locations with great heterogeneity in vegetation height, thereby maximizing both food abundance and accessibility, and (3) adult birds forage selectively for specific prey items.
Methods We measured food availability in relation to vegetation structure, habitat use and nestling diet for six individual nests. Nestling diet was determined by microscopic analysis of faeces while food availability over different vegetation heights was estimated by suction sampling. Information on habitat use was gathered by direct observation. Foraging locations were compared to random locations at the same distance from the nest.
Results Nestling diet mainly consisted of larger spiders (> 5 mm) (38% of prey individuals), caterpillars (c. 2 cm) (38%), other insect larvae (12%) and flies and wasps (7%). There was a positive relationship between vegetation height and prey availability. Contrary to predictions, vegetation at Pipit foraging locations was less heterogeneous than at random locations, yet we found no evidence for a preference for short or tall vegetation. We found strong evidence for selective foraging for larger prey, since the relative abundance of especially large spiders and caterpillars was much higher in the faecal samples than in the field. This diet differed considerably from Meadow Pipit diet reported from other habitats.

Conclusion These findings suggest that the creation of heterogeneity in vegetation height by grazing or otherwise may not be invariably beneficial to breeding Meadow Pipits.

Post-Breeding Migration of Dutch-Breeding Black-Tailed Godwits: Timing, Routes, Use of Stopovers, and Nonbreeding Destinations

Author(s): Hooijmeijer, Jos C. E. W.; Senner, Nathan R.; Tibbitts, T. Lee; et al.
Source: ARDEA, 101 (2): 141-152 FAL 2013

Abstract: Conservation of long-distance migratory shorebirds is complex because these species use habitats spread across continents and hemispheres, making identification of critical habitats and potential bottlenecks in the annual cycle especially difficult.
The population of Black-tailed Godwits that breeds in Western Europe, Limosa limosa limosa, has declined precipitously over the past few decades. Despite significant efforts to identify the root causes of this decline, much remains unclear. To better understand the migratory timing, use of stopover and nonbreeding sites, and the potential impact of breeding success on these parameters, we attached 15 Argos satellite transmitters and 10 geolocation tracking devices to adult godwits nearing completion of incubation at breeding sites in southwest Friesland, The Netherlands during the spring of 2009.
We successfully tracked 16 adult godwits for their entire southward migration and two others for part of it.
Three migration patterns and four regions of use were apparent. Most godwits left their breeding sites and proceeded south directly to stopover sites in the Mediterranean — e.g. Spain, Portugal, and Morocco — before flying on to non-breeding sites in West Africa. Other individuals spent the entire nonbreeding season in the Mediterranean. A third pattern included a few individuals that flew nonstop from their Dutch breeding sites to nonbreeding sites in West Africa. Tracking data from this study will be immediately useful for conservation efforts focused on preserving the dispersed network of sites used by godwits during their southward migration.

Birdsong is not all about sexual selection: Female birds sing much more often than previously thought

In 71% of all songbird species with available data, the female sings too. This is remarkable because in the wake of Darwin's theory of evolution, birdsong has generally been seen as a characteristic of male birds, allowing them to compete with other males and attract females.

Leiden biologist Katharina Riebel published this finding on 4 March in Nature Communications, together with an international team.

Message to Darwin: Birdsong is not all about sexual selection 

The team studied the available literature on the song of female songbirds. This resulted in the first worldwide survey and the first study of song in females of primitive songbird species.

The team used a genetic databank to map the characteristics and evolution of these female songbirds. Their analysis shows that in the common ancestors of modern songbirds of both males and females must have had song. Leiden biologist Riebel says that 'the origin of birdsong must therefore lie not only in sexual selection and competition among males, as suggested by Darwin. It seems more probable that sexual and social selection also played a role in females: song allowed both males and females to compete for the resources necessary for survival and reproduction.'

Lees meer: ScienceDaily

Lemmings fuel biggest snowy-owl migration in 50 years

For the lowly Arctic lemming, life is cruel. In a flash before death, often the last things a lemming sees are the deadly talons of a majestic snowy owl. A mass sacrifice of this rodent with stubby legs probably gave rise to what scientists are calling the largest snowy-owl irruption in at least half a century. The gleaming white birds poured out of Canada this winter to points throughout the eastern US, captivating birdwatchers, scientists and people who had never seen them up close.

Their flights, covering thousands of kilometres, were fuelled by a steady diet of lemmings. The lemming population spikes about every four years in the Arctic, and last summer it rose off the charts on Canada's Bylot Island in the Nunavut territory.

Lees meer: theGuardian