Demography
Mortality and Survival
All radiocollars we will use have mortality sensors. We will locate collars in mortality mode as soon as possible and we will try to determine cause of death. We will search for signs of fisher predation on lynx because of the documented predation by fishers on lynx in Maine (Vashon et al. 2003). Incisor gap measurements on puncture wounds of dead lynx will be a primary means to determine the cause of mortality (or identify the scavenger). After the kill site has been investigated, carcass portions will be removed for later laboratory necropsy.
Additional information on lynx mortality can be obtained from necropsies of other carcasses found within the state. Necropsies will include collection of hair and tissue samples, physical condition estimates by body weight, body fat, or examination of bone marrow, and standard morphological measurements collected on captured lynx (Appendix 3), age estimation by tooth examination or sectioning, examination of gastrointestinal tract contents, and placental scar counts. After necropsy, all lynx carcasses collected in Minnesota will be disposed of in accordance with established FWS procedures.
Survival rates on radio-collared lynx will be estimated using either the Kaplan-Meier method (Kaplan and Meier 1958, Pollock et al. 1989a, b, White and Garrott 1990) or the Heisey-Fuller version (Heisey and Fuller 1985, White and Garrott 1990) of the Mayfield method (Mayfield 1961, 1975). Selection of the particular survival estimation method will be based on the sample size of lynx radiocollared. Winterstein et al. (2001) suggest the use of the Mayfield method when less than 25-50 animals are obtained. Comparisons will be made between sexes and age classes for annual, seasonal (summer and winter) and cause-specific mortality. The seasonal delineation can also be expressed in a more biologically relevant classification scheme consisting of a breeding-gestation period and a parturition-kitten rearing period (Nielsen and Woolf 2002). Chi-square tests in CONTRAST (Hines and Sauer 1989, Sauer and Williams 1989) will be the statistical method used to test for differences in annual and seasonal survival. If mortality rates differ between sexes and among age classes on a seasonal basis, we will also investigate the cause-specific factors involved.
Reproduction and Recruitment
Radiocollared female lynx will be monitored for localized movements during spring that may indicate the establishment of a natal den Maine (Vashon et al. 2003). When localized movements are detected the den site will be marked with a GPS location during a telemetry flight. A radiocollar may be wrapped in protective material and dropped near the den site from the plane to more efficiently locate the den (Vashon et al. 2003). Kittens will be captured by hand, fitted with ear tags and weighed. Morphological measurements and tissue samples will be collected from kittens. Litter sizes will be compared among years with analysis of variance (ANOVA) and within individual years among age-classes with a t-test if sample sizes are large enough. Snow tracking information collected during the tagged kittens’ first winter will provide supplemental information on kitten survival and recruitment into the population.
Dispersal and Emigration
Dispersal and emigration will be detected because radiocollared animals are being relocated weekly. Telemetry coverage will be extended to > 50 km from the SNF if necessary to detect long-distance movements of adult or juvenile lynx (Mech 1977). Any lynx that establish territories within this extended range will continue to be monitored as time and funding permit. If signals are lost, we will attempt to locate animals with the help of nearby researchers who may be able to pick up the animal within the expected range of exploratory and dispersal movements (Squires and Laurion 2000, Vashon et al. 2003).