Avian sibling cannibalism: Hoopoe mothers regularly use their last hatched nestlings to feed older siblings

Sibling cannibalism is relatively common in nature,but its evolution in birds and certain other vertebrates with extended parental care had been discarded.Here,however,we demonstrate its regular occurrence in two European populations of the Eurasian hoopoe(Upupa epops)and explore possible adaptive and non-adaptive explanations.Results showed that sibling cannibalism was more frequently detected in Spain(51.7%)than in Austria(5.9%).In these two populations,the hoopoes laid similar clutch sizes,resulting in similar fledging production,but hatching failures were more frequent in the northern population.Consequently,having more nestlings condemned to die in the southern population may explain the higher incidence of sibling cannibalism.In accordance with this interpretation,hatching span and failure,but not breeding date,explained the probability of sibling cannibalism in the Spanish hoopoes,while all three variables predicted brood reduction intensity.Furthermore,experimental food supply reduced the probability of sibling cannibalism,but not the intensity of brood reduction.Finally,females allocated fewer resources to the smallest nestlings when they were going to starve,but not necessarily when they were going to be used as food for their siblings.These results suggest that hoopoes produce extra eggs that,in the case of reduced hatching failure and food scarcity,produce nestlings that are used to feed older siblings.These findings provide the first evidence that sibling cannibalism occurs regularly in a bird species,thus expanding our evolutionary understanding of clutch size,hatching asynchrony,parent-offspring conflict,infanticide,and sibling cannibalism in the animal kingdom.

Context dependent song-flight performance and timing in the Black-headed Bunting(Emberiza melanocephala)

Many songbirds produce song-flights;however,the function,vocal and motor characteristics,as well as the diel and seasonal variation of song-flight in songbirds remain not well understood.Here,we studied two types of song-flight in male Black-headed Buntings(Emberiza melanocephala),the Moth—a standard,i.e.,perch song produced during a horizontal flight,and the Towering—a specifically structured song produced during a complex ascending and descending flight.While perch song,used during Moth flight,has already been described,here we provide the first description and sonogram representation of the more elaborate and less stereotyped Towering song.While males started to perform Moth song-flights as soon as they arrived at the breeding site,Towering did not start before the female arrival.Males usually delivered spontaneous Moth song-flights before chasing rivals or undertaking aerial fights,suggesting Moth is directed towards conspecific males and serves as a threat display.Furthermore,playback of conspecific perch songs triggered males to approach the loudspeaker with Moth song-flights.The Towering started after females arrived at the breeding site,suggesting the Towering is directed towards conspecific females.We detected a seasonal difference in the peak Towering rate between forenoon and afternoon,suggesting that Towerings performed at different times of the day have different functions.Forenoon Towerings were strongly positively related to the number of fertile females at the breeding site,while afternoon Towerings peaked very early in the breeding season and coincided with the number of females at the breeding site before the onset of nest-building.These results provide evidence that birds can direct different types of song-flight towards different receivers and suggest the possibility that time of the day determines the context of the display,namely to attract social mates or solicit copulation.Further work is needed to account for the effect of between male variability in song-flight rate,as well as in height/steepness of flight or song quality.

Mate choice is affected by parasite infestation rate of the choosing individual as well as of potential mating partners

Parasites are known to be a key driving force in mate choice and are important for the expression and evolution of ornaments and behavioral traits being used.However,there is little experimental evidence on how the parasite’s burden of the choosing individual is integrated into the mate-choice process and how it affects decision-making,especially in relation to parasite infestation of potential mates.Thus,the aim of our study was to determine whether female house sparrows Passer domesticus adjust their mate preference according to their own as well as the parasite load of prospective partners.To do this,we experimentally manipulated female parasite load and determined their mate preferences prior to and after parasite treatment.We manipulated the chronic coccidian parasite burden of females either by initiating the acute infection phase via re-infecting them with coccidian or by temporally reducing the parasite load of coccidia.We then measured the effect of this manipulation on mate preference by presenting females with a choice of four stimuli:three males with similar ornaments,but unmanipulated,naturally varying chronic coccidiosis levels,and an unmanipulated control female.Additionally,we recorded some males’behavior in relation to their infection status pointing toward an increased or reduced interest in mating.We found that females preferred highly infested males prior to manipulation,regardless of their own infestation level.However,after manipulation,infested females avoided highly infested males probably in response to the deterioration of their health condition by parasites.Our study suggests that mate-choice decisions are more complex when they are mediated by parasites.The implications of parasites for evolutionary theories of sexual signaling and mate choice are discussed.

Can house sparrows recognize familiar or kin-related individuals by scent?

In the last decades, higher attention has been paid to olfactory perception in birds. As a consequence, a handful of avian species have been discovered to use olfaction in different contexts. Nevertheless, we still have a very limited knowledge about the use of odor cues in avian social life, particularly, in the case of songbirds. Here, we investigate if female house sparrows Passer domesticus show any preference for the odor of kin and nonkin conspecifics and we also test a possible role of familiarity based on male see nt in female choice. We performed the experiment with captive birds twice, duri ng the non breeding and breedi ng seas ons. Our results show that female house sparrows strongly avoided the odor of unrelated familiar (UF) males, both in the breeding and nonbreeding seasons. Our results suggest recognition for olfactory stimuli related to familiarity and kin ship. We suggest that avoidance for UF males is associated with previous experie nee in this species. Also, we provided further evidenee to the use of olfaction in passerine species by using a new experimental setup.