Demographics of Canada geese introduced in western Colorado

Abstract

Breeding populations of Canada geese (Branta canadensis) were established throughout western Colorado during 1955–1988 using geese transplanted from other areas. Subsequently, there has been no assessment of demographics and winter distributions on these local populations. Managers need this information to effectively manage breeding populations of Canada geese to provide publics with recreational opportunities and to reduce human‐goose conflicts in western Colorado, particularly for segments of internationally recognized populations with cooperative management plans. We conducted a band recovery study during 2000–2006 to assess demographics and winter distributions of Canada geese breeding in 7 subareas of western Colorado. Cooperators banded 19,189 geese during June and early July. We recaptured 5,185 of these geese 1–4 times during banding operations in subsequent years and most (97%) were recaptured in the subarea of banding the year after banding. We obtained 2,921 useable band recoveries through May 2007, and most (98%) recoveries were a result of either being shot or found dead during hunting season. Direct band recoveries (<1 year after banding) were recovered almost exclusively in Colorado (87%) and New Mexico (12%), and indirect band recoveries (≥1 year after banding) showed similar distribution (73% in Colorado and 16% in New Mexico). Geese in subareas of western Colorado had different recovery distributions, and contributed to 4 wintering concentrations of Canada geese in western and central Colorado and New Mexico. Annual survival probability for adult geese was 0.864 ± 0.012. The survival probability for juvenile geese was 0.503 ± 0.026, but we did find evidence that this estimate may be biased low. We used the band reporting probability of 0.525 ± 0.071 to derive harvest rates from band recovery rates. Harvest rate was 0.128 ± 0.018 for adult geese and 0.169 ± 0.024 for juvenile geese. Survival probability was lesser and harvest rate greater for the 3 western subareas (Western Plateau) compared to the 4 eastern subareas (Rocky Mountains). Our results suggest that Canada geese that breed and molt in western Colorado have high survival probability and are largely non‐migratory with some movement in winter from high to low elevation areas primarily in Colorado. To effectively manage the growing resident goose population in western Colorado, managers may need to increase harvest rates for these geese. © 2014 The Wildlife Society.

Demographic consequences of translocation of overabundant Canada geese breeding in urban areas

“…As expected from previous studies and early anecdotal observations from Wascana, fidelity to the release site was higher for immature geese, whereas adult geese exhibited high philopatry to the trapping site (Surrendi , Smith , Iverson et al , Sanders and Dooley ). Because we did not make observations at the release site, we do not know how frequently immature birds returned specifically to the Cumberland area as opposed to areas nearby.…”

“…Population abundance at Wascana did not decline in parallel with translocation, despite extensive translocation effort. Thus, although we can offer to managers that immature geese are the best candidates for translocation to reduce local abundance via recruitment (or to establish populations via fidelity; Sanders and Dooley ), these vacancies were likely filled by immigration from outside sources because the population growth observed at Wascana mirrored that observed for the larger Western Prairie‐Great Plains population (Vrtiska et al ). Indeed, translocation alone may be insufficient to reduce local geese abundance if individuals remain in good body condition from feeding in agricultural lands during the wintering period and are released from density‐dependent competition upon return to breeding areas (Fox et al ).…”

“…In numerous urban settings across North America, increasing Canada goose ( Branta canadensis ) population sizes pose a significant challenge to wildlife managers (Groepper et al , Balkcom , Sanders and Dooley ). Managers have a limited number of techniques to deal with urban geese that have varying acceptance by the public.…”

“…Changes in local population size could arise from effects of local survival and movements of immature and adult geese among sites (Alisauskas et al , Norris et al ). Translocation of immature and adult geese could reduce a nuisance population of geese, but this effect may be dampened if a large number of geese return to the original site the following year (Surrendi , Fritzell and Soulliere , Sanders and Dooley ). To justify translocation, the population size at the donor site should be expected to stabilize or decline if a large proportion of translocated geese remain at the new site (Fritzell and Soulliere , Sanders and Dooley ).…”

“…Translocation of immature and adult geese could reduce a nuisance population of geese, but this effect may be dampened if a large number of geese return to the original site the following year (Surrendi , Fritzell and Soulliere , Sanders and Dooley ). To justify translocation, the population size at the donor site should be expected to stabilize or decline if a large proportion of translocated geese remain at the new site (Fritzell and Soulliere , Sanders and Dooley ). Additionally, if translocation subsequently leads to lower survival of geese, it raises doubts about whether translocation is a humane alternative relative to a lethal cull.…”