54 research outputs found
The density of the invertebrate summer fauna on the crowns of pine trees, Pinus sylvestris in the central part of the Netherlands.
Die Dichte der Sommerfauna der Invertebraten in den Kronen der Kiefern (auĂer Mikrolepidopteren, Aphiden, Psociden, Jassiden und Milben) wurde in den Jahren 1967-1971 fĂźr die Monate Juni, Juli, August und September ermittelt. Die Proben wurden den Bäumen entnommen, indem man Zweige vorsichtig in einen groĂen Sack schnitt. Nachdem die Tiere mit Kohlendioxyd getĂśtet worden waren, wurden sie durch kräftiges SchĂźtteln der Zweige Ăźber einem Tuch aus diesen entfernt.The density of the invertebrate fauna on the crowns of pine trees (microlepidoptera, aphids, psocids, jassids and mites excepted) has been assessed in June, July, August and September over the years 1967-1971. Trees have been sampled by cutting twigs and carefully putting them into a large sack. After having been killed by carbondioxyde the animals were dislodged from the twigs by shaking the latter thoroughly over a cloth
Dietary complexity and hidden costs of prey switching in a generalist top predator
Variation in predator diet is a critical aspect of food web stability, health, and population dynamics of predator/ prey communities. Quantifying diet, particularly among cryptic species, is extremely challenging, however, and differentiation between demographic subsets of populations is often overlooked. We used prey remains and data taken postmortem from otter Lutra lutra to determine the extent to which dietary variation in a top predator was associated with biotic, spatial, and temporal factors. Biotic data (e.g., sex, weight, and length) and stomach contents were taken from 610 otters found dead across England and Wales between 1994 and 2010. Prey remains were identified to species where possible, using published keys and reference materials. Multiâmodel inference followed by model prediction was applied to test for and visualize the nature of associations. Evidence for widespread decline in the consumption of eels (Anguilla anguilla ) reflected known eel population declines. An association between eel consumption and otter body condition suggested negative consequences for otter nutrition. Consumption of Cottus gobio and stickleback spp. increased, but was unlikely to compensate (there was no association with body condition). More otters with empty stomachs were found over time. Otter sex, body length, and ageâclass were important biotic predictors of the prey species found, and season, region, and distance from the coast were important abiotic predictors. Our study is unique in its multivariate nature, broad spatial scale, and longâterm dataset. Inclusion of biotic data allowed us to reveal important differences in costs and benefits of different prey types, and differences between demographic subsets of the population, overlaid on spatial and temporal variation. Such complexities in otter diet are likely to be paralleled in other predators, and detailed characterization of diet should not be overlooked in efforts to conserve wild populations
Neanderthal Use of Fish, Mammals, Birds, Starchy Plants and Wood 125-250,000 Years Ago
Neanderthals are most often portrayed as big game hunters who derived the vast majority of their diet from large terrestrial herbivores while birds, fish and plants are seen as relatively unimportant or beyond the capabilities of Neanderthals. Although evidence for exploitation of other resources (small mammals, birds, fish, shellfish, and plants) has been found at certain Neanderthal sites, these are typically dismissed as unusual exceptions. The general view suggests that Neanderthal diet may broaden with time, but that this only occurs sometime after 50,000 years ago. We present evidence, in the form of lithic residue and use-wear analyses, for an example of a broad-based subsistence for Neanderthals at the site of Payre, Ardèche, France (beginning of MIS 5/end of MIS 6 to beginning of MIS 7/end of MIS 8; approximately 125â250,000 years ago). In addition to large terrestrial herbivores, Neanderthals at Payre also exploited starchy plants, birds, and fish. These results demonstrate a varied subsistence already in place with early Neanderthals and suggest that our ideas of Neanderthal subsistence are biased by our dependence on the zooarchaeological record and a deep-seated intellectual emphasis on big game hunting
To eat or not to eat? The diet of the endangered iberian wolf (Canis lupus signatus) in a human- dominated landscape in central Portugal
Livestock predation by large carnivores and their persecution by local communities are
major conservation concerns. In order to prevent speculations and reduce conflicts, it is crucial
to get detailed and accurate data on predatorsâ dietary ecology, which is particularly important
in human dominated landscapes where livestock densities are high. This is the case
of the endangered Iberian wolf in Portugal, an endemic subspecies of the Iberian Peninsula,
which has seen its population distribution and abundance decline throughout the 20th century.
Accordingly, the diet of the Iberian wolf was analyzed, using scat analysis, in a humanized
landscape in central Portugal. From 2011 to 2014, a total of 295 wolf scats were
collected from transects distributed throughout the study area, prospected on a monthly
basis. Scat analysis indicated a high dependence of Iberian wolf on livestock. Domestic
goat predominated the diet (62% of the scats), followed by cow (20%) and sheep (13%); the
only wild ungulate present in the scat analysis was the wild boar (4% of the scats). Our results
show that even though livestock constitute most part of wolves diet, different livestock
species may represent different predation opportunities. We conclude that the high levels
of livestock consumption may be a result of low diversity and density of wild ungulates
that settles livestock as the only abundant prey for wolves. Our findings help on the understanding
of the Iberian wolf feeding ecology and have implications for conflict management
strategies. Finally, management implications are discussed and solutions are
recommended
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