In our latest post, author Rebecca Levine gives us tips on how to date under environmental pressure! Discussing the article: “Thermal conditions alter the mating behavior of males in a polygynous system”, which was recently published in Functional Ecology, Rebecca shares insight behind the sometimes complex physiological tradeoffs male moose are faced with in order to successfully find mates. Through her work, combined with a strong sense of local collaboration, Rebecca helps shine a light on the subtle drawbacks species face due to climate change.
About the paper
Males in polygynous systems face a tradeoff between traits that enhance reproductive success and the need to cope with environmental change. To secure mates, males invest into large bodies, lavish ornaments, and costly movements, but these investments may be incompatible with changing environments. As climate change intensifies, increased environmental temperature could be affecting reproductive success. For male moose (Alces alces), successful reproduction is determined each autumn during a brief but intense mating season. They spar with rival males, search for solitary females, and guard their potential mates. Old males, who tend to have large bodies and antlers, are typically the most successful at securing mates. During this time, males have to maximize access to females, avoid injuries from rivals, and retain enough energy to survive winter. To complicate this tricky balance, moose are heat-sensitive and increasing autumn temperatures may limit their movement during this critical period. The large bodies and antlers that make older males successful at securing mates, also make them more sensitive to heat, meaning the traits that usually make males the ‘winners’ of the mating season, could hurt their chances as the climate continues to warm.
We studied how traits like age and antler size interacted with environmental conditions to shape the mating tactics, effort, and opportunity of male moose. We measured mating opportunity as time spent near females. What we found was that indeed, heat was most limiting to the movement of old and large males! However, though heat affected movement, it did not change mating opportunity. Old males put less effort into movement but had greater mating opportunity. This was fascinating because despite heat limiting movement, traits like age, body size, and antler size were more important to achieving mating success than movement behavior. Our findings demonstrate how the nuances of a mating system greatly affect when and how climate change affects reproduction. For moose, even though warm temperatures affect behavior, they are not yet disrupting mating opportunities, likely because of the dynamics of their mating system. Our work highlights tradeoffs between physical traits and reproductive behaviors and emphasizes how the nuances of a mating system can mediate the effects of climate change on reproduction.
About the research
The project came to be because of a passionate community member who was concerned about declining moose populations in the region. Studies of moose ecology tend to focus on females since they rear offspring and have a more direct effect on population numbers. With this work, we had the unique opportunity to study how the sexes interact and how their ecology differs. We initiated the work in 2020, capturing and tagging moose in a small population along the Absaroka Mountains in Wyoming. Through this work, we advanced techniques for the capture and handling of moose, studied their thermoregulatory behaviors over the summer, and dug into the mating behavior of males. Future work will involve understanding female mate choice and behavior during the mating season. This research was part of the Meeteetse Moose Project, a collaboration between the Wyoming Game and Fish Department and the Monteith Shop at the University of Wyoming.
About the authors
I have always loved watching animals and trying to figure out why they do what they do. This interest led to me running the Meeteetse Moose Project as part of my graduate work at the University of Wyoming. Though my research interests vary, I get most excited about research that spans, combines, or contrasts different parts of ecology; whether that’s pairing physiology and habitat selection, mating behavior and thermoregulation, or nutrition and movement! Generally, I love it when my work can apply classic ecological principles to the study of global change. Studying moose has been the ultimate adventure! Whether I’m capturing them, tracking their movements, pondering their lives, or attempting to avoid close encounters, moose always keep me guessing. Through it all, I could not have asked for better co-authors. Bart Kroger, our partner at the Wyoming Game & Fish, spent his career building an incredible knowledge of the area and cultivating the local relationships that made this work possible. And Kevin Monteith, my graduate advisor, provided invaluable mentorship, expertise, and encouragement.
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