Using public participation and genetic mark-recapture data to estimate urban moose population demographics

Effective wildlife management often requires data on population size, survival, sex ratios, and site fidelity; however, obtaining these metrics can be difficult in areas or years when traditional techniques such as aerial surveys are ineffective or prohibitive, resulting in a need for alternative sampling techniques. In this study, we developed a methodology for estimating demographics of an urban moose (Alces alces) population by combining reports from the public and genetic mark-recapture data. From 2018–2021, we elicited the public's help during a 3-day period in late February to locate moose for biopsy sampling in Anchorage, Alaska, USA. Each year, >800 reports from the public allowed us to obtain 891 biopsy samples. Combined with an additional 493 samples obtained from roadkilled or harvested moose, we identified 837 unique individuals with 433 recapture events (recapture rate = 59%). Using genetic mark-recapture techniques, we estimated there to be 306 (95% CI = 222–390) moose within Anchorage, a relatively high density (1.5 moose/km²) suggesting urban areas may have perceived advantages to moose such as reduced predation risks, greater foraging opportunities, or lower snow depths on plowed roads and groomed trails. Additionally, moose exhibited high winter site fidelity and moved <3.0 km between captures on average. However, survival rates of adults (73%; 95% CI = 60–83%) and calves (i.e., individuals surviving from 9 months of age to the subsequent February survey; 48%; 95% CI = 32–65%) were low, suggesting urban areas may act as an ecological trap due to mortality risks from vehicle collisions. This study showed that by eliciting public participation in an urban environment, genetic mark-recapture was a feasible alternative to traditional aerial surveys to estimate moose population demographics, a technique that could easily be adapted to other urban areas and wildlife species.