Visual Head Counts: A Promising Method for Efficient Monitoring of Diamondback Terrapins

Diversity

Sean Sterrett¹  Patricia Levasseur²  Chris Sutherland² 

[1] Department of Biology, Monmouth University, West Long Branch, NJ 07764, USA;Department of Environmental Conservation, University of Massachusetts–Amherst, Amherst, MA 01003, USA;

关键词: abundance;    detection;    diamondback terrapin;    Malaclemys terrapin;    monitoring;    N-mixture;    salt marsh;    visual-head count;   

DOI  :  10.3390/d11070101

来源: DOAJ

【 摘 要 】

Determining the population status of the diamondback terrapin (Malaclemys terrapin spp.) is challenging due to their ecology and limitations associated with traditional sampling methods. Visual counting of emergent heads offers a promising, efficient, and non-invasive method for generating abundance estimates of terrapin populations across broader spatial scales than has been achieved using capture−recapture, and can be used to quantify determinants of spatial variation in abundance. We conducted repeated visual head count surveys along the shoreline of Wellfleet Bay in Wellfleet, Massachusetts, and analyzed the count data using a hierarchical modeling framework designed specifically for repeated count data: the N-mixture model. This approach allows for simultaneous modeling of imperfect detection to generate estimates of true terrapin abundance. Detection probability was lowest when temperatures were coldest and when wind speed was highest. Local abundance was on average higher in sheltered sites compared to exposed sites and declined over the course of the sampling season. We demonstrate the utility of pairing visual head counts and N-mixture models as an efficient method for estimating terrapin abundance and show how the approach can be used to identifying environmental factors that influence detectability and distribution.

【 授权许可】

Unknown