Nethy & Deshar

We're tracking two osprey chicks, Nethy and Deshar, from their nest at Loch Garten, Scotland as they migrate for the first time.

Follow the highs and lows of their journey with us right here.


The RSPB: Loch Garten Ospreys

Mirror Self-recognition In Magpie Birds

Self-recognition, it has been argued, is a hallmark of advanced cognitive abilities in animals. It was previously thought that only the usual suspects of higher cognition—some great apes, dolphins, and elephants—were able to recognize their own bodies in a mirror.

Psychologist Helmut Prior and colleagues have shown evidence of self-recognition in magpies—a species with a brain structure very different from mammals.

Lees meer: Science Daily

Owls May Use Faeces and Prey Feathers to Signal Current Reproduction

by Vincenzo Penteriani, Maria del Mar Delgado

Background

Many animals communicate by marking focal elements of their home range with different kinds of materials. Visual signaling has been demonstrated to play a previously unrecognized role in the intraspecific communication of eagle owls (Bubo bubo), in both territorial and parent-offspring contexts. Visual signals may play a role in a variety of circumstances in this crepuscular and nocturnal species.

Methodology/Principal Findings

Here, we report that a large amount of extremely visible white faeces and prey feathers appear during the breeding season on posts and plucking sites in proximity to the nest, potentially representing a way for eagle owls to mark their territory. We present descriptive and experimental evidence showing that faeces and prey remains could act as previously unrecognized visual signals in a nocturnal avian predator. This novel signaling behavior could indicate the owls' current reproductive status to potential intruders, such as other territorial owls or non-breeding floaters. Faeces and prey feather markings may also advertise an owl's reproductive status or function in mate-mate communication.

Conclusions/Significance

We speculate that faeces marks and plucking may represent an overlooked but widespread method for communicating current reproduction to conspecifics. Such marking behavior may be common in birds, and we may now be exploring other questions and mechanisms in territoriality.

Lees meer: PLoS One

Raptors Survival Can Be Threatened By Ingesting Lead And Cadmium

Birds of prey accumulate environmental pollutants distributed in the surroundings and, in some cases, these can cause death. A comparative study of raptors in Galicia and Extremadura undertaken by Spanish researchers has confirmed their exposure to two potentially toxic agents, lead (Pb) and cadmium (Cd). The data obtained can be used to detect the toxicological effects in terrestrial ecosystems.

Birds of prey that live in extensive geographical areas can accumulate high levels of heavy metals and metalloids in their bodies, as they are top of their food chain. Now researchers from the Universidad de Extremadura and from the Universidad de Santiago de Compostela can reveal that these wild animals can provide extremely useful data to detect and evaluate the toxicological effects of different inorganic elements in terrestrial ecosystems. This information could also be extrapolated to human beings.

Lees meer: Science Daily

Sustained bird flights occur at temperatures far beyond expected limits

Auteur(s): Heiko Schmaljohann, Bruno Bruderer, Felix Liechti
Bron: ANIMAL BEHAVIOUR, doi:10.1016/j.anbehav.2008.05.024
Abstract: Migratory birds deposit fat and protein before passing ecological barriers and must economize these during such crossings. Birds crossing the western Sahara during autumn face a trade-off between cold and humid air along with head winds at high altitudes versus warm and dry air along with tail winds at low altitudes. Since water loss rate increases with temperature, migrants should avoid warm and dry air to save water and hence fly at high altitudes.
By quantifying nocturnal songbird migration across the western Sahara with radar, we found that more than 60% of the songbirds migrated below 1000 m above ground level. Thus, the majority of songbirds performed sustained migratory flights in much warmer and drier conditions than predicted (weighted means: 30 °C; relative humidity: 27%; water vapour density: 7.8 g/m3). Based on the metabolically available water from fat and protein catabolism, we estimated the maximum possible overall water loss rate of a flying model bird, the garden warbler, Sylvia borin, for the entire Sahara crossing at 0.29 g/h. This is considerably lower than water loss rates for the same model bird passing our study site, 0.62 g/h at 30 °C, based on applied calculations of physiological studies.
Our results clearly show that migrating songbirds can fly at much higher temperatures, and have considerably lower water loss rates, than predicted. This new insight based on observations under natural conditions will have substantial impact on the development of new physiological models for birds and other animals with restricted access to water.

The impact of raptors on the abundance of upland passerines and waders

Auteur(s): Arjun Amar, Simon Thirgood, James Pearce-Higgins, Steve Redpath
Bron: OIKOS Volume 17 Issue 8, Pages 1143-1152
Abstract: The issue of predator limitation of vertebrate prey populations is contentious, particularly when it involves species of economic or conservation value. In this paper, we examine the case of raptor predation on upland passerines and waders in Scotland. We analysed the abundance of five wader and passerine species on an upland sporting estate in southern Scotland during an eight-year period when hen harrier, peregrine and merlin numbers increased due to strict law
enforcement.
The abundance of meadow pipit and skylark declined significantly during this time. Golden plover also showed a declining trend, whereas curlew increased significantly and there was a near significant increase in lapwings. Contrasting the local population
trends of these species with trends on nearby areas revealed higher rates of decline for meadow pipit and skylark at the site where raptors increased, but no differences in trends for any of the three wader species.
There was a negative relationship between the number of breeding harriers and meadow pipit abundance the same year and between total annual raptor numbers and meadow pipit abundance. Predation rates of meadow pipit and skylark determined from observations at harrier nests suggested that predation in June was sufficient to remove up to
40% of the June meadow pipit population and up to 34% of the June skylark population.
This 'quasi-natural' experiment suggests that harrier predation limited the abundance of their main prey, meadow pipit, and possibly the abundance of skylark. Thus, high densities of harriers may in theory reduce the abundance of the prey species which
determine their breeding densities, potentially leading to lower harrier breeding densities in subsequent years. We found no evidence to suggest that raptor predation limited the populations of any of the three wader species. We infer that concerns over the impact of natural densities of hen harriers on vulnerable upland waders are unjustified.

Trawling: a major threat to albatrosses

A study of trawl fishing in South Africa suggests that around 18,000 seabirds may be killed annually in this fishery, highlighting trawl fisheries as a major threat to seabirds, especially several species of albatross already facing a risk of extinction.

Lees meer: The RSPB

Going, Going, Gone: Is Animal Migration Disappearing

Animal migration surely ranks as one of nature's most visible and widespread phenomena. Every minute of every day, somewhere, some place, animals are on the move. The migrants span the animal kingdom, from whales and warblers to dragonflies and salamanders. But is migration an endangered phenomenon? Around the world, many of the most spectacular migrations have either disappeared due to human activities or are in steep decline. Those of us living in eastern North America can no longer experience the flocks of millions of passenger pigeons that temporarily obscured the sun as they migrated to and from their breeding grounds. Nor can residents of the Great Plains climb to the top of a hill and gaze down up hundreds of thousands of bison trekking across the prairies, as was possible less than two centuries ago.

Lees meer: PLoS Biology

When to be a dear enemy: flexible acoustic relationships of neighbouring skylarks, Alauda arvensis

Auteur(s): Elodie Briefer, Fanny Rybak, Thierry Aubin
Bron: ANIMAL BEHAVIOUR doi:10.1016/j.anbehav.2008.06.01
Abstract: Numerous territorial species are less aggressive towards neighbours than strangers. This tolerance towards neighbouring conspecifics, termed the ‘dear enemy’ effect, seems to be a flexible feature of the relationship between neighbours, and has been shown to disappear in some species after experimental or natural modifications of the context. However, the maintenance over time of this singular relationship has been poorly studied.
In this study, we followed the change of dear enemy relationships during the breeding season in a territorial songbird with a complex song, the skylark. We examined in the field the response of territory owners to playbacks of neighbour and stranger songs at three periods of the breeding season, corresponding to three ecological and social situations.
Results showed that neighbours were dear enemies in the middle of the season, when territories were stable, but not at the beginning of the breeding season, during settlement and pair formation, nor at the end, when bird density increased owing to the presence of young birds becoming independent. Thus, the dear enemy relationship is not a fixed pattern but a flexible one likely to evolve with social and ecological circumstances.

Within-brood social status and consequences for winter hierarchies amongst Mallard Anas platyrhynchos ducklings

Auteur(s): Maud Poisbleau, Matthieu Guillemain, Laurent Demongin, David Carslake, Joan David
Bron: JOURNAL OF ORNITHOLOGY DOI 10.1007/s10336-008-0334-6
Abstract: Juveniles of many birds establish dominance hierarchies within family social units, only to leave and compete to acquire dominance status in new social groups. Little is known about the role of sex, body mass, size or experience during the duckling period on subsequent dominance rank and adult social relationships.
We used captive Mallard Anas platyrhynchos ducklings to test for the role of individual characteristics and growth parameters in establishing within-brood hierarchies, the maintenance of within-brood hierarchies in the subsequent wintering group and differences in social ranks between broods. Strong stable linear hierarchies were present within each brood and, later, within each phase of the winter. There was a reorganisation of the hierarchical order between the duckling period and early winter, but only few modifications afterwards during the winter.
None of the tested "hatching", "duckling" and "adult" traits explained either the within-brood or the winter hierarchies, but winter rank was related to brood of origin with ducklings from the same brood having similar social ranks. These differences between broods were maintained through the whole winter in most cases, though one brood drastically progressed in the hierarchy during late-winter.
These results suggest that the factors affecting the establishment of social relationships within broods differ from those in winter groups, and that brood-related mechanisms influence social relationships during winter. We discuss our results in the light of direct and indirect maternal influence.

Avian Cooperation: Rooks Work Together to Solve Puzzle for Food

Birds of a feather don’t just flock together—they also work together to obtain food. Recent research makes rooks the first nonprimates observed to successfully cooperate to retrieve a food-laden platform, according to a June 22 study in the journal Proceedings of the Royal Society B: Biological Sciences.

Lees meer: Scientific American