Bull Elk Survival and Antler Size Analysis

Factors Affecting Antler Size

This workflow contain a suite of generalized linear mixed-effect models(GLMMs) to assess the effects of age, migratory status, and forage biomass (quality) on male elk antler size. We use 3 sets of models to test different questions with slightly different subsets of data due to varying samples sizes available for each analysis. We test the relationship between antler size and elk age to first determine the age model that best describes and accounts for the relationship between age and antler size. Next, we assess the effect of migratory tactic and biological year on antler size. Lastly, we test for the effect of summer forage biomass from GPS location data to test the relationship between forage biomass and antler size.

Male Elk Survival

We derived non-parametric Kaplan-Meier survival estimates and test for factors affecting survival during the hunting season using Cox-proportional hazards models. We tested categorical differences in annual survival between age classes (2-3,4,5+) to account for differences in vulnerability to harvest under 3 and 6-pt antler point restrictions. 

We determined factors effecting survival during the hunting season using the time-to-event framework of the Cox-proportional hazard modeling. We present models to test the effect of 3 age-classes, predicted antler size, distance to road, migratory tactic, and inside vs outside a protected area, and hunting regulations on male elk survival during the hunting season.

Male Elk Cause-Specific Mortality

We estimated cause-specific mortality of radiocollared elk from wolf, recreational harvest, First Nations harvest, starvation, or unknown (non-predator) using cumulative incidence functions (CIFs). We then tested for differences between CIFs for migratory tactics and years using Gray's test. 

Please see publication for more details about the analysis and results.