Clarke Margaret R, Glander Kenneth E
Tulane National Primate Research Center, Covington, LA 70433, USA.
Primates. 2010 Jul;51(3):241-9. doi: 10.1007/s10329-010-0195-5. Epub 2010 Mar 26.
Natal emigration by male and female mantled howlers (Alouatta palliata), and subsequent immigration into breeding groups, is well documented for the free-ranging population on Hacienda La Pacifica, Costa Rica, but secondary transfer was considered rare (Glander in Int J Primatol 3:415-436, 1992). Population surveys in 1998 and 2006 caused us to question our assumptions and to re-evaluate our long-term data set from a post hoc perspective. We first identified all animals observed or captured as adults in more than one non-natal group anywhere in the population. We then systematically analyzed joining or leaving by adults in seven groups tracked for various times from 1975 to 2005 for patterns suggesting secondary transfer. Fourteen adults (nine females, five males) were found in two different non-natal groups as adults. In addition, one male and one female that became dominant and reproduced in their natal group later transferred to a second group, and one female was known to be a tertiary transfer. Data from the seven tracked social groups indicate that 35% of all the males and 29% of all the females were potential secondary transfers. In these groups, males leaving or joining was not associated with group size or absolute number of females. Females leaving or joining was not associated with group size or absolute number of males, but females left groups with more females and joined groups with fewer females. Both sexes left groups with unfavorable sex ratios for their sex and joined groups with sex ratios more favorable for their sex. Since a favorable sex ratio is associated with reproductive success in other howler populations, this suggests secondary transfer as a reproductive strategy. Other factors could also influence secondary transfer.
在哥斯达黎加太平洋庄园的野生鬃毛吼猴（Alouatta palliata）种群中，雄性和雌性吼猴的出生后迁出以及随后迁入繁殖群体的情况有充分记录，但二次转移被认为很少见（格兰德，《国际灵长类学杂志》3：415 - 436，1992年）。1998年和2006年的种群调查使我们对自己的假设产生质疑，并从事后的角度重新评估我们的长期数据集。我们首先确定了在种群中任何地方被观察到或捕获时已是成年个体且处于不止一个非出生群体中的所有动物。然后，我们系统地分析了1975年至2005年期间不同时间跟踪的七个群体中成年个体的加入或离开情况，以寻找表明二次转移的模式。发现有14只成年个体（9只雌性，5只雄性）在成年时处于两个不同的非出生群体中。此外，有一只雄性和一只雌性在其出生群体中成为优势个体并繁殖后代，后来转移到了第二个群体，还有一只雌性已知是三次转移。来自这七个被跟踪社会群体的数据表明，所有雄性中有35%以及所有雌性中有29%是潜在的二次转移个体。在这些群体中，雄性的离开或加入与群体大小或雌性的绝对数量无关。雌性的离开或加入与群体大小或雄性的绝对数量无关，但雌性会离开雌性较多的群体，加入雌性较少的群体。两性都会离开性别比例对其不利的群体，加入性别比例对其有利的群体。由于有利的性别比例与其他吼猴种群的繁殖成功相关，这表明二次转移是一种繁殖策略。其他因素也可能影响二次转移。
