fatalityCMR—Capture-Recapture Software to Correct Raw Counts of Wildlife Fatalities Using Trial Experiments for Carcass Detection Probability and Persistence Time

Abstract

Many industrial and agricultural activities involve wildlife fatalities caused by collision, poisoning, or other involuntary harvest, including wind turbines, highway networks, utility networks, tall structures, and pesticides. Affected wildlife may have official protection, including a monitoring requirement. Carcass counts are typically conducted to quantify the number of fatalities, but they need to be corrected for carcass persistence time (as influenced by removal by scavengers and decay) and detection probability (searcher efficiency). This report introduces new software developed by the U.S. Geological Survey (USGS) in cooperation with the U.S. Fish and Wildlife Service that fits a superpopulation capture-recapture model to raw count data. It uses trial data to estimate detection and daily persistence probabilities and combine these estimates with the carcass count data in an integrated model. A recurrent issue is that fatalities of rare, protected species are infrequent, in which case the software offers the option to switch to an “evidence of absence” mode based on binomial laws and estimate the probability of not finding a carcass. The software allows users to distinguish between different location types (for example, different vegetation cover or different technical properties of the devices causing fatalities), as well between two carcass age-classes or states with transition between those classes (for example, fresh and old). A data simulation feature can be used at the planning stage to optimize sampling design. Resulting mortality estimates can be used to (1) quantify the required amount of compensation, (2) inform mortality projections for proposed development sites, (3) inform decisions about management of existing sites, and (4) improve the design of carcass search protocols and trial experiments.

First posted April 17, 2014