Volume 230, 16 August 2016, Pages 42–46
Highlights
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- We studied barn owl dietary changes by analysing pellets.
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- Barn owls switched from eating mostly rodents to eating a higher proportion of anurans.
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- Barn owl diet shifts may be associated with rodent population decline resulting from habitat loss.
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- Rapid farming intensification promoted landscape homogenisation and habitat loss.
Abstract
Biodiversity
ecosystem services in agroecosystems are negatively affected by
farmland homogenisation due to intensive agriculture. The Pampas, an
important worldwide region producing commodity crops, have been greatly
homogenised with the expansion no-tillage and herbicide-tolerant
transgenic soybeans since the 1990s. Here, we tested the hypothesis of
that dietary changes in barn owls will be associated with the loss of
semi-natural habitats derived from farming intensification. We
characterised the dietary habits of western barn owls by analysing their
pellets between two sampling periods (2004–2005 and 2010–2012). We also
assessed the habitat loss due to cropping intensification through
fencerow removal and pasture conversion to annual crops during the same
period. We observed that barn owls shifted from eating mostly rodents in
the first sampling period to eating a higher proportion of anurans in
the second sampling period. Between sampling, rodent proportion in
pellets decreased from 80% to 61.6%, while anuran proportion increased
from 20% to 37.7%. A rapid farming intensification occurred on the farm
between both sampling periods. Pastures were ploughed to grow annual
crops. Thus, the annually cropped area increased by 60% from 2004 to
2012, while the area with pastures was reduced in about 80%. During the
same period, nearly two-thirds of fences on the farm were removed to
enlarge the cropped area. Our findings suggest that dietary habits of
barn owls may shift to consume more anurans when rodent availability
declines in association with the loss of semi-natural habitats, which
resulted from rapid farming intensification on the studied farm. We
suggest monitoring the population size and diet of barn owls for
evaluating environmental changes produced in agroecosystems by farming
intensification, as well as the adaptive responses of different rodent
and anuran species to such changes.
Keywords
- Agricultural intensification;
- Agroecosystems;
- Biodiversity;
- Land-use change;
- Landscape homogenization;
- Prey-predator relationships;
- Trophic relationships
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