Accounting for tagging-to-harvest mortality in a Brownie tag-recovery model by incorporating radio-telemetry data.
The Brownie tag-recovery model is useful for estimating harvest rates but assumes all tagged individuals survive to the first hunting season; otherwise, mortality between time of tagging and the hunting season will cause the Brownie estimator to be negatively biased. Alternatively, fitting animals with radio transmitters can be used to accurately estimate harvest rate but may be more costly. We developed a joint model to estimate harvest and annual survival rates that combines known-fate data from animals fitted with transmitters to estimate the probability of surviving the period from capture to the first hunting season, and data from reward-tagged animals in a Brownie tag-recovery model. We evaluated bias and precision of the joint estimator, and how to optimally allocate effort between animals fitted with radio transmitters and inexpensive ear tags or leg bands. Tagging-to-harvest survival rates from >20 individuals with radio transmitters combined with 50-100 reward tags resulted in an unbiased and precise estimator of harvest rates. In addition, the joint model can test whether transmitters affect an individual's probability of being harvested. We illustrate application of the model using data from wild turkey, Meleagris gallapavo, to estimate harvest rates, and data from white-tailed deer, Odocoileus virginianus, to evaluate whether the presence of a visible radio transmitter is related to the probability of a deer being harvested. The joint known-fate tag-recovery model eliminates the requirement to capture and mark animals immediately prior to the hunting season to obtain accurate and precise estimates of harvest rate. In addition, the joint model can assess whether marking animals with radio transmitters affects the individual's probability of being harvested, caused by hunter selectivity or changes in a marked animal's behavior.
Pennsylvania Cooperative Fish and Wildlife Research Unit, Pennsylvania State University University Park, Pennsylvania, 16802.
Frances E
FE
Buderman
U.S. Geological Survey Pennsylvania Cooperative Fish and Wildlife Research Unit, Pennsylvania State University University Park, Pennsylvania, 16802.
Duane R
DR
Diefenbach
Pennsylvania Game Commission, Bureau of Wildlife Management 2001 Elmerton Ave., Harrisburg, Pennsylvania, 17110.
Mary Jo
MJ
Casalena
Pennsylvania Game Commission, Bureau of Wildlife Management 2001 Elmerton Ave., Harrisburg, Pennsylvania, 17110.
Christopher S
CS
Rosenberry
Pennsylvania Game Commission, Bureau of Wildlife Management 2001 Elmerton Ave., Harrisburg, Pennsylvania, 17110.
Bret D
BD
Wallingford
Auxiliary data; Brownie model; harvest rate; hunter behavior; joint model; known-fate; survival rate; tag recovery