Wildlife Hormones and Behavioral Ecology
Rock hyrax
Procavia capensis
Our primary model is the wild rock hyrax (Procavia capensis) in the Ein Gedi Nature Reserve, which Lee has studied since 1998. Hyraxes are highly social, living in groups that consist of both sexes, with female dominance. Female testosterone is as high as males’, yet they reproduce annually, nursing multiple offspring for up to a year. Hyraxes are diurnal, facilitating behavioral observations. As a graduate student, Lee developed tools to visually mark hyrax and record their social, agonistic, maternal, and vocal behaviors. Projects in this system have involved sexual selection, social status and stress, social and sexual networks, maternal behavior, and acoustic communication. Prof. Eli Geffen (Tel Aviv University) and Dr. Amiyaal Ilany (Bar Ilan University) are collaborators in this system.
Nutrias
Myocastor coypus
Nutria (Myocastor coypus) are invasive in the Hula valley. They show fluctuating sex ratios across groups and years, with males bigger than females throughout life. Females in good condition selectively abort small litters that are predominantly female, and quickly reconceive a litter bearing numerous small females or a few large males. The current culling program allows us to collect a large number of pregnant females, and through detailed necropsies examine the relationship between maternal hair testosterone and offspring sex ratios. We also measure fetal steroids using hair samples grown in utero during the second trimester, to study the contribution of maternal and sibling steroid levels to individual fetuses, and the effects of testosterone on reproduction and fetal survival. The nutria projects are in collaboration with Dr. Yoni Vortman (Tel-Hai Academic College) and Prof. Uri Shanas (University of Haifa - Oranim).
Humans
Homo sapiens
Although difficult to monitor and study, we have several projects on human sociality, reproduction, and sex ratios. Human hair grows at an average rate of 1cm per month. This allows hair segmentation, and measurement of steroid levels backdating to the time targeted by the study (e.g., fetal conception, war, exams, etc.). Through collaborations with psychologists, sociologists, medical doctors, and hospitals at large, we address key questions in behavioral ecology and sociobiology, such as the effect of steroids on birth sex ratios and fetal outcomes, social behaviour, learning, attention, maternal, and attachment behaviors.
Argya squamiceps
Arabian babbler
Since 2020, we have been we have been studying the Arabian babbler (Argya squamiceps) at the Sheizaf Nature Reserve as part of the Zahavi Arabian Babbler Research Station (www.zahavibabblers.com), in collaboration with Dr. Oded Keynan (Arava Centre). The social behaviour of these iconic territorial, desert-dwelling, obligately cooperative breeding birds were the inspiration for the late Prof. Amotz Zahavi to generate the Handicap Hypothesis. Over 20 social babbler groups are habituated to human observers making this system ideal to explore the causal roles of glucocorticoids and their receptors in dominance hierarchies, social network equality and stability, group extinction, and individual fitness. By examining integrated measures of corticosterone in feather samples, and experimentally manipulating acute levels using spiked meal worms, we explore the process of social evolution and complexity, cooperation, and conflict resolution. The uniqueness of this system lies in the combination of long-term data already collected over > 50 years, babbler groups of different genetic relatedness, social make-up, and predictable longevity, the opportunity to observe social behaviour up close, and non-invasively sample and manipulate circulating glucocorticoid levels.