02399nas a2200181   4500008004100000245011800041210006900159300001300228490000700241520177400248653001202022653002502034653003002059653001902089653002602108100001702134856006602151       2009                        eng d00aParent-absent begging in the Brown-headed Cowbird (Molothrus ater): the role of short-term need and nestmate size0 aParentabsent begging in the Brownheaded Cowbird Molothrus ater t  a707 -7170 v633 a<p>Although it is well-established that nestlings of many altricial species beg when parents are away from the nest, we have a poor understanding of parent-absent begging in brood parasites, including the proximate factors that may influence begging frequency and intensity. In this study, I examined how parent-absent begging was influenced by competitive asymmetries between host and Brown-headed Cowbird (Molothrus ater) nestlings under disparate levels of short-term need. Food-deprived cowbird nestlings begged more frequently and for a greater proportion of parent-absent period than when food-supplemented, with similar patterns observed in hosts of different sizes. In contrast, three metrics of cowbird begging intensity varied relative to host size but not due to differences in short-term need. Cowbirds consistently begged more frequently and intensively than host nestlings for a given level of short-term need, providing evidence that cowbird begging displays are more frequent and intense than non-parasitic nestlings during both feeding visits and parent-absent periods. In sum, the frequency of begging by cowbirds was only influenced by short-term need, whereas begging intensity during parent-absent events was only influenced by the host against which cowbirds competed. This study demonstrates that host size and short-term need had differing influences on the frequency and intensity of parent-absent begging in cowbirds, although both factors are likely important in limiting the evolution of parent-absent begging in cowbirds. Because it appears to provide no immediate benefits yet may decrease fitness, parent-absent begging should be included in future theoretical models investigating the evolution of begging displays in nestling birds.</p>10abegging10abrown-headed cowbird10ageneralist brood parasite10aMolothrus ater10aParent-absent begging1 aRivers, J.W.  uhttps://link.springer.com/article/10.1007%2Fs00265-008-0704-3