Midwest Primate Interest Group meetings!

In a couple weeks, one of my favorite conferences, MPIGs, is coming up!  I'm really excited for this year, because I have both a podium and poster presentation.  Also, I'm finally going to meet a couple of my fellow primatology bloggers, Raymond of Prancing Papio, and Ashlee of This is Serious Monkey Business.

 Here are my abstracts for the presentations!

Podium Presentation

Seasonality, activity patterns, and cortisol in female spider monkeys in a wet forest environment.

Seasonality plays a crucial role in shaping the ecological context in which individuals live, which in turn shapes their internal processes.  The glucocorticoids, or stress hormones, are crucial in allocating the body’s resources in accordance with ecological demands, and most animal species experience seasonal variation in glucocorticoid concentrations. Here, I report on the effects of seasonality and activity patterns on cortisol concentrations in wild subadult and adult female spider monkeys, at El Zota Biological Field Station in Costa Rica.  Over a 15-month research period, mean individuals rates of time engaged in rest are significantly negatively correlated with mean cortisol concentrations (Spearman’s rho=-0.737, p=0.010. N=11).  No other activity variable was significantly associated with mean cortisol concentrations. Additionally, over the course of a year, the effects of monthly fruit abundance, mean party size, and activity variables were assessed.  Although fruit abundance and party sizes did significantly vary between seasons, cortisol concentrations did not.  Furthermore, in a general linear model, none of these variables significantly explain variation in monthly cortisol concentrations, although a non-significant trend was observed between time engaged in rest and cortisol concentrations ((F=4.703, p=0.082).  These results indicate that in this mildly seasonal environment, variability in fruit abundance and party size has little effect on cortisol concentrations.  Rather, time engaged in rest appears to be the most important factor in affecting individual’s cortisol concentrations.

Poster Presentation

Whinnies, grooming, and estradiol in wild female spider monkeys.

Identifying hormonal correlates of social behavior in primates can help us understand variation in specific social behaviors across individuals.  Here, I report preliminary results of a study of behavior and endocrinology in wild adult and subadult female spider monkeys from El Zota Biological Field Station, Costa Rica, over a 15-month period.  Estradiol concentrations were assayed from fecal samples collected from recognized females using Enzyme-immunoassay (EIA) techniques. Over the entire research period, mean individual rates of whinny vocalizations were significantly correlated with mean estradiol concentrations (Spearman’s rho=0.818, two-tailed p=0.002, N=11).  Furthermore, both whinny rates (Spearman’s rho=-0.755, two-tailed p=0.007, N=11) and estradiol concentrations (Spearman’s rho=-0.764, two-tailed p=0.006, N=11) were significantly negatively correlated with mean grooming rates.  These findings cannot be accounted for by differences in age, reproductive state, or parity.  Previous studies have indicated a sex difference in whinny production rates, with females producing more whinnies than males. The results of this study suggest that endogenous hormonal factors may affect whinny production, and these factors may underlie the pronounced sex differences observed for this vocalization. The negative relationship between whinnies and grooming indicate that whinnies may serve as a form of “vocal grooming” that plays a role in maintaining social bonds in a less time-exhaustive manner.