Age class dynamics of Canada geese in the Central Flyway

• Published in: The Journal of Wildlife Management
• Main Authors: Dooley, Joshua L., Szymanski, Michael L., Murano, Rocco J., Vrtiska, Mark P., Bidrowski, Tom F., Richardson, Josh L., White, Gary C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2019
• Subjects: Canada; Branta canadensis; Canada Goose
• Online Access: http://dx.doi.org/10.1002/jwmg.21639; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjwmg.21639; https://onlinelibrary.wiley.com/doi/pdf/10.1002/jwmg.21639; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/jwmg.21639

ABSTRACT Abundance of temperate‐nesting Canada geese ( Branta canadensis ) in Central Flyway east‐tier states (ND, SD, NE, KS, OK, USA) increased since the 1970s. Hunting regulations were liberalized since the mid‐1990s in these states to increase harvest and reduce abundance of local populations. Because 2 age classes, juvenile and adult, are typically classified when banding, most dead‐recovery band analyses of Canada geese have only considered 2 age classes to estimate survival and recovery probabilities, despite a delayed breeding life history. We evaluated recovery distributions and survival and recovery probabilities of Canada goose age classes (i.e., juvenile [first year], subadult [second and third year], and adult [≥fourth year]) among Central Flyway east‐tier states relative to liberalized hunting regulations during 1990–2015. We also conducted simulations and evaluated bias in parameter estimates from 2‐age‐class dead‐recovery models when a subadult age class was not modeled. Models including 3 age classes were more supported than models including only 2 age classes. Mean juvenile survival estimates among states from the top 2‐age‐class models were 9–50% greater than an equivalent 3‐age‐class model, whereas differences were less or negligible for adult survival (−4% to −1%), adult recovery (1–12%), and juvenile recovery (−3–6%). Geese were primarily recovered in the state they were banded (range among states = 59–86%), and 91% of all recoveries occurred in the Central Flyway east‐tier states. Recovery distributions of subadults were broader and more northward than adults and juveniles. Recovery estimates (Brownie parameterization) of subadults among states ( = 0.091 ± 0.039 [SE] to 0.116 ± 0.029) were also generally greater than adults (0.061 ± 0.030 to 0.104 ± 0.033) and juveniles (0.049 ± 0.026 to 0.132 ± 0.041). Survival estimates of adults (0.713 ± 0.103 to 0.748 ± 0.119) and subadults (0.621 ± 0.197 to 0.801 ± 0.154) exhibited some decrease through time concurrent with liberalized harvest ...