據(jù)美國(guó)《科學(xué)》雜志在線報(bào)道,，它們并不是在游戲,。研究人員指出，這是第一個(gè)例證,，表明一種水生哺乳動(dòng)物能夠利用道具進(jìn)行性展示,。在6000多只亞馬遜河豚中，研究人員發(fā)現(xiàn)有221只河豚——其中大多數(shù)是雄性——使用了這些小道具,。雄性的這種行為往往在接近雌性時(shí)才會(huì)出現(xiàn),，并且主要集中在7月份——比大多數(shù)雌亞馬遜河豚生育寶寶的時(shí)間提前了14個(gè)月。沒(méi)有人知道亞馬遜河豚的孕期到底有多長(zhǎng),，但其他海豚和小型鯨的孕期為11到15個(gè)月,。研究人員在3月25日的《生物學(xué)快報(bào)》（Biology Letters）網(wǎng)絡(luò)版上報(bào)告了這一研究成果。（來(lái)源：科學(xué)時(shí)報(bào) 群芳）
生物谷推薦原始出處：
（Biology Letters）,，10.1098/rsbl.2008.0067,，A.R. Martin, V.M.F. da Silva, P. Rothery
Object carrying as socio-sexual display in an aquatic mammal
A.R. Martin1, V.M.F. da Silva2, P. Rothery3
1NERC Sea Mammal Research Unit, University of St Andrews, Fife KY16 8LB, UK
2LMA, Instituto Nacional de Pesquisas da Amazônia, 69011-790 Manaus, Amazonas, Brazil
3 CEH Monks Wood, Abbots Ripton, Huntingdon, Cambridgeshire PE28 2LS, UK
Amazon river dolphins or botos (Inia geoffrensis Blainville) were observed carrying objects in 221 social groups over a 3-year study period. Sticks, branches and clumps of grass were taken from the water surface and often repeatedly thrashed or thrown. Lumps of hard clay were collected from the river bed and held in the mouth while the carrier rose slowly above the surface and submerged again. Carriers were predominantly adult males and less often subadult males. Adult females and young dolphins rarely carried objects. Groups of dolphins in which object carrying occurred were differentially large and comprised a greater proportion of adult males and adult females. Aggression, mostly between adult males, was significantly associated with object carrying. The behaviour occurred year-round, with peaks in March and July. A plausible explanation of the results is that object carrying by adult males is aimed at females and is stimulated by the number of females in the group, while aggression is targeted at adult males and is stimulated by object carrying in the group. We infer that object carrying in this sexually dimorphic species is socio-sexual display. It is either of ancient origin or has evolved independently in several geographically isolated populations.
