Population Size and Characteristics of Alouatta pigra Before and After a Major Hurricane

• Published in: International journal of primatology 2007-08, Vol.28 (4), p.919-929
• Main Authors: Pavelka, Mary S. M., McGoogan, Keriann C., Steffens, Travis S.
• Format: Article
• Language: English
• Subjects: Alouatta pigra; Animal behavior; Animal populations; Environmental risk; Hurricanes; Monkeys & apes; Natural disasters; Population number; Primates; Storms; Watersheds
• ISSN: 0164-0291; 1573-8604
• DOI: 10.1007/s10764-007-9136-6

Although some environmental risks and resources are known to affect the evolution of primate social groups, we know little about the effect of major natural disturbances on primate populations. Hurricane Iris hit the Monkey River watershed in southern Belize in October 2001, presenting a unique opportunity to document the effects of a natural disaster under circumstances wherein some pre-hurricane data were available. We measured the characteristics of the population of black howlers in the affected forest 3.5 years after the storm and compared the population data with pre-hurricane data from a 52-ha study area, that may represent the larger continuous riverine forest and from which all monkeys were known. From February to May 2004, we sampled 28.77 km^sup 2^ of the 96-km^sup 2^ forest fragment via five transects walked 12 times each. From these data we estimate that the population in the watershed has dropped from 9784 to 1181 monkeys, a reduction of 88%, reflected by both a 79% drop in the number of social groups and a 38% reduction in group size. Before the storm, 75% of the social groups were multimale; after the storm, 74% of the groups were unimale. While the ratio of adult females to males improved slightly, the ratio of adults to immatures, and adult females to immatures more than doubled, indicating a much lower potential for growth. These data provide a quantitative assessment of how a major natural disturbance can affect a primate population.[PUBLICATION ABSTRACT]