Exploring food preferences and the limits of foraging

CAMÍN S; CUETO V; LOPEZ DE CASENAVE J; MARONE L

EMU

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2015 p. 261 - 269

0158-4197

Habitat degradation caused by cattle grazing may be a serious threat for seed-eating birds because theavailability of beneficial seeds usually diminishes in grazed areas. Ecologically plastic species might, however, circumventfood deprivation via changes in foraging behaviour. We studied the limits of feeding flexibility and factors affecting seedpreferences in Zonotrichia capensis, Diuca diuca, and Saltatricula multicolor.We experimentally assessed preferences forseeds of eight grass and eight forb species by using a protocol that combines choice and non-choice trials, and employed adifferent batch of experiments to evaluate some plausible causes of different feeding flexibility. On average, birds consumed45?140% more grass than forb seeds, confirming previous results. Z. capensis preferred several grass and forb seeds, andshowed maximum feeding flexibility. S. multicolor and, to a lesser extent, D. diuca, were grass specialists that preferredlarge and medium-sized grass seeds. The size of forb seeds did not affect preferences. Coat thickness of grass seeds didnot seriously reduce consumption levels. Birds showed low ability to feed on resources characteristic of degradedenvironments (i.e. annual grass seeds). Species-specific differences in behavioural flexibility could be used to predictdietary and numerical responses of seed-eating birds to habitat degradation.