August
30, 2017
Before
habitat degradation from impacts like grazing begins to cause population
declines, the first response by wildlife usually comes in the form of
behavioral changes—for example, switching their diets in response to changes in
food availability. A new study from The Condor: Ornithological
Applications looks at the diets of seed-eating birds in a South American
desert and finds that while some can switch between seed types when grazing
alters local plant communities, others continue to stick to old favorites,
limiting their options.
Luis
Marone of the Argentine Arid Zones Research Institute (IADIZA-CONICET) and his
colleagues collected soil samples at grazed and ungrazed sites in Argentina's
Monte Desert to assess the composition of the seed bank in each area, finding fewer
of the large grass seeds that birds prefer in the grazed areas. Flushing the
digestive tracts of captured birds revealed that two seed generalists, Common
Diuca-Finch and Rufous-collared Sparrow, adjusted their diet accordingly and
ate more forb seeds at grazed sites, while grass seed specialists Many-colored
Chaco Finch and Ringed Warbling-Finch did not.
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