Germination of native and exotic seeds dispersed by wild black-and-gold howler monkeys (Alouatta caraya): assessing deinhibition and scarification effects.

Fruit ingestion by frugivores and the subsequent passage of seeds through their digestive tract can influence seed germination patterns. The removal of germination inhibitors contained in the fruit pulp (deinhibition effect), and/or the abrasion of the seed coat (scarification effect), can modify the probability and speed of seed germination. We followed seven groups of black-and-gold howler monkeys (Alouatta caraya) in northeastern Argentina between November 2012 and January 2013 to study the effect of seed passage through the howler monkeys' gut on seed germination. For three native and one exotic species, we compared the proportion of germination and germination times among seeds in three different treatments: gut-passed seeds (GP), manually extracted seeds from fruits (ME), and seeds in intact fruits (IF). Paired comparisons between treatments allowed us to assess the overall effect of seed passage (total effect without distinguishing individual effects, GP vs. IF), deinhibition effect (ME vs. IF), and scarification effect (GP vs. ME). Our results suggest that passage through the howler monkeys' gut enhances seed germination by an increase in the proportion of germinated seeds and/or by a reduction in germination times. We found that deinhibition enhanced germination in three out of the four studied species, while scarification enhanced germination in one and decreased germination in another species. Our work highlights that gut passage may affect seed germination by different mechanisms, and all of these mechanisms should be considered in germination studies. It also emphasizes the importance of A. caraya as a seed disperser in northeastern Argentina, showing the high quality of the treatment provided to seeds.

Adoption of an orphaned and temporarily captive infant by an unrelated adult female in black-and-gold howler monkey: implications for management strategies.

Conservation behavior involves the application of general principles of animal behavior for solving conservation problems. In primates, adoption of infants has been reported in several species and consists of an individual other than the biological parents taking primary care of them. Based on cases of adoption reported in howler monkeys (genus Alouatta), in the present study we facilitated the adoption of an orphaned and temporarily captive male infant by an unrelated adult female black-and-gold howler monkey (A. caraya), in the wild. The adoption process involved presenting the orphaned infant, inside a cage, to the female in the forest fragment that she occupied. We recorded the interactions between the individuals, and decided to open the cage. The female became the sole caregiver of the orphan, providing him with protection, transportation, and feeding, although she did not nurse him. The follow-up of these same individuals between 2006 and 2007 confirmed the success of the adoption. These findings indicate that carefully managed adoption can be a possible management strategy for the conservation and the welfare of howler monkeys in both nature and captivity.