Home About us Contact
|
Home About us Contact | ||
|
|
||
Paired Males (paired + male)
Selected AbstractsStrophe Length in Spontaneous Songs Predicts Male Response to Playback in the Hoopoe Upupa epopsETHOLOGY, Issue 5 2004Manuel Martín-Vivaldi Hoopoe (Upupa epops, Coraciformes) males produce a very simple song during the breeding season in order to attract females and repel intruders. Strophes vary in length (i.e. number of elements) both within and between males, and previous studies have shown that this song cue is positively correlated with male condition and breeding success. In the present study we tested whether strophe length of males influences male behaviour during intra-sexual contests, in a colour-ringed population in southeast Spain. Paired males were presented with a recorded song with long strophes during the pre-laying period, while they were near their mates, in order to provoke male mate-defence behaviour. Most males responded to the playback, but the strategy of defence adopted depended on their own strophe length in spontaneous songs recorded before the experiments. While singing responses were common to most of the males, only those using long strophes adopted the most risky strategy of approaching the loudspeaker. However, the males that approached produced abnormal songs during playback, that were shorter and with fewer strophes than those of males that did not approach, and used shorter strophes in comparison with spontaneous songs before the experiment. These differences in quality of the song produced in response to the playback suggest that long-strophe males were basing their response mainly on attacking rather than singing, while short-strophe males tried to resolve the contest at a distance by means of their song. These results show that strophe length reflects some component of the competitive ability of males (either physical strength or aggressiveness) in the hoopoe, which together with previous results regarding its role for female choice, show that it is a sexual signal with dual function. [source] Does Booby Egg Dumping Amount to Quasi-Parasitism?ETHOLOGY, Issue 7 2006Marcela Osorio-Beristain Quasi-parasitism occurs when a paired male facilitates dumping in its own nest by an extra-pair female with which it has recently copulated. Although numerous observations hint at quasi-parasitism in diverse avian species, direct behavioral confirmation of male complicity is required to exclude the alternative adaptive explanations enumerated by Griffith et al. [Behav. Ecol. Sociobiol.56 (2004) 191]. Our direct observations on dumping by female blue-footed boobies (Sula nebouxii) show apparent male ambivalence: males were hostile to eggs dumped by their extra-pair partners but half-hearted in repelling those partners after the act of dumping. Hostility was evidenced when a host male that was present during dumping destroyed the extra-pair partner's egg and when extra-pair partners selectively dumped when the host male was absent or distracted rather than when it was alone on the territory. Host males appear to deter dumping by their extra-pair partners rather than facilitating it, and their partial tolerance of females that have dumped may be a result of their general tolerance of unaccompanied females. Although paired male boobies sometimes copulate with females that dump into their nests, apparently this is not quasi-parasitism. [source] Sex and the Single Vole: Effects of Social Grouping on Prairie Vole Reproductive SuccessETHOLOGY, Issue 10 2002Karen E. Hodges Prairie voles (Microtus ochrogaster) have a mating system that is primarily monogamous with paired males and females together defending breeding space against intruders of either sex. Breeding success may be affected when other adults intrude on the territorial space of pairs. We conducted an experiment to determine the impact of additional members of either sex on reproductive success of pairs. In laboratory arenas, we formed pairs (1F:1M) and two kinds of triad (2F:1M, 1F:2M). Females in pairs had the highest conception rates, litter sizes and survival of litters. Females in 1F:2M groups had slightly reduced litter sizes and reduced numbers of weanlings, and some females had litters sired by both males. Females in 2F:1M groups had low conception rates and the smallest litters, and >35% of their litters suffered infanticide; in no case did both females become pregnant. Throughout the trials, individuals of the sex doubly represented in triads were more likely to die than were individuals of the sex singly represented. We conclude that there may be fitness costs associated with the presence of unrelated supernumerary adults during gestation and lactation. [source] Habitat selection and reproductive success of Ortolan Buntings Emberiza hortulana on farmland in central Sweden , the importance of habitat heterogeneityIBIS, Issue 3 2008ĹKE BERG Many granivorous birds have shown severe population declines in Europe during recent decades. The aim of the present study was to analyse habitat preferences and reproductive success of one such species, the Ortolan Bunting Emberiza hortulana, in different farmland habitats in south-central Sweden. Four seemingly different land-use types were preferred: permanent set-asides, short rotation coppice, and grazed and unmanaged semi-natural pastures. Territories and random sites differed considerably in the proportion of these preferred land-use types; 39% of territories had > 70% preferred habitat (at the 100-m scale) compared to 5% of random sites. In contrast, 22% of territories and 65% of random sites had no preferred habitats. All the preferred habitats had heterogeneous ground vegetation characterized by patches with bare ground, or at least sparse ground vegetation, intermixed with patches with taller vegetation. Ortolan Buntings also preferred a heterogeneous habitat structure with occurrence of field islets, shrubby edges, barns and electric wires, which could act as song posts or suitable nest-sites, in 88% of territories. At a larger (1-km square) scale, territories occupied by pairs aggregated strongly in areas with high proportions of preferred habitats. The number of territories with single males correlated positively with the number of pairs, which suggests that conspecific attraction may influence territory distribution. No measured habitat factors were related to reproductive success. However, due to habitat preferences and the higher proportion of paired males in one habitat type (set-aside), the production of young (fledglings/ha) is expected to be higher in set-asides, as well as in short-rotation coppices and semi-natural pastures. Thus, these habitats are important for the conservation of the Ortolan Bunting. Large areas with habitat structures such as field islets are especially important because the Ortolan Bunting breeds in aggregations in these areas. [source] | ||||||||||