Distributed research project to test for parallel urban-to-rural clines

Project background: Urban areas are the fastest growing ecosystem on Earth. Ecological conditions vary sharply between cities and rural areas, and cities are more similar to each other in many respects than to adjacent rural lands (e.g., extensive impervious cover). The novel conditions found in cities are hypothesized to cause parallel evolution of trait variation, but tests of parallel evolution are often limited by the logistical constraints of conducting studies across multiple, replicate cities. We seek to form a network of collaborators to test across multiple cities in North America whether urbanization causes parallel evolution of coat color in eastern gray squirrels (Sciurus carolinensis). Gray squirrels commonly have two coat colors – gray and black – inherited in a simple Mendelian fashion at the melanocortin-1 receptor gene. Previous work suggests differences in crypsis between color morphs in urban and rural environments may generate clines in melanism, but widespread tests for urban-rural clines in squirrel melanism have been limited to analyses of incidental observations of squirrels via community science (e.g., iNaturalist). Here we seek your collaboration as a partner to test for urban-rural clines in melanism using wildlife cameras as a standardized sampling approach. The protocol is designed to also function as an educational activity for engaging students (grades 9-12 and undergraduates) in field surveys of mammal populations.

Basic approach: Camera traps will be used to document the occurrence and relative abundance of each morph along an urbanization gradient. Collaborators will establish camera traps at 20-30 sites along at least one urban-to-rural transect in their home city. Camera traps will be left in place for 4 weeks and then removed. Collaborators will also conduct a short visual survey for squirrels when deploying and retrieving camera traps. Check out our sampling protocol for all the details.

Materials and cost: For labs that have camera traps and SD cards already, the only costs are batteries for the cameras and gas for transportation. If you would like to participate but do not have camera traps, you can purchase your own camera trap equipment. Camera traps sufficient for this project run about $100-150/each. SD cards are about $5 each, and you can get a pack of batteries to run up to 30 cameras for about $50. Optional equipment includes a security case and lock for each camera. We may have a limited number of camera traps that we can loan out for a four-week sampling timeframe, so if you’d like to participate but cannot purchase your own equipment, please still feel free to contact us.

Authorship: Groups of up to two individuals who collect camera trap data in at least one city following the guidelines below will be offered authorship on the first paper published with the aggregate data collected (see below for more details).

Timing: Sampling must be conducted prior to August 2022.

Which cities?: For now we are restricting this project to cities in the native range of eastern gray squirrels, focused in the upper Midwest, northeastern US, and southeastern Canada (see map of study area below). Click here to see a map of cities currently enrolled in the study.