Which geese are being harvested? Body condition of lesser snow (Chen caerulescens caerulescens) and Ross’s Geese (C. rossii) harvested by different methods during the light goose conservation order.
August 2014 - December 2019
- Nebraska Game and Parks Commission
The increase of mid-continent light goose populations over the past thirty years and subsequent impacts to Arctic and sub-Arctic habitats has been well documented (e.g., Abraham and Jefferies 1997, Jefferies et al. 2004). Liberalization of regular season hunting regulations and initiation of a light goose conservation order (LGCO) in both Canada and the United States were implemented to decrease mid-continent light goose populations to help alleviate impacts to northern habitats. Despite the liberalizations of hunting regulations, which have increased harvest (Kruse and Fronczak 2012), current efforts appear to be ineffective in reducing light goose populations (Alisauskas et al. 2011). Harvest of certain segments of light goose populations may not be aiding in population reduction. Preliminary data collected during spring 2012 in Nebraska indicated that light geese harvested over decoys weighed approximately 100g less than those harvested by pass shooting or sneaking and stalking. Although the total number of light geese harvested with various methods are unknown, survey data from participants in the light goose conservation order in Nebraska indicate that >70% of hunters/participants use electronic calls (M. Vrtiska, Nebraska Game and Parks Commission, unpublished data), meaning that a large percentage of light geese in Nebraska are harvested over decoys. Thus, if most of the individuals harvested in the light goose conservation order are in poorer body condition than the general population, and populations are structured through compensative mortality, current harvest strategies may actually benefit populations by lessening impacts of competition for food and other resources. Additionally, species, sex, and age composition of the harvest during the LGCO and possible implications for harvest management have not been assessed. Rockwell and Ankney (2000) indicated that 1.41 million light geese would need to be harvested to have an effect on the population. While Ross’s geese have been identified as overabundant in the U.S. (Moser 2001), the primary species impacting Arctic and sub-Arctic habitats are lesser snow geese. Disproportionate harvest of Ross’s geese may decrease the effectiveness of the LGCO in reducing lesser snow goose populations and conserving those habitats. From band recovery information, Alisauskas et al. (2011) reported that the LGCO had proportionally greater influence on adult survival, but also recognized that large numbers of juveniles were being harvested and fewer juveniles may be available to LGCO harvest after fall and winter mortality. Because the majority of lesser snow geese do not breed until 3 years of age (Cooke et al. 1995), harvest of a disproporitonate number of juvenile birds may have a latent effect on populations. Finally, if males are more susceptable to harvest, then the effectiveness of the LGCO is reduced given adult female survival is the key parameter in population reduction (Rockwell et al. 1997). Thus, differential vulnerability between lesser snow and Ross’s geese, juvenile vs. adults, and males vs. females all may impact the effectiveness of the LGCO on reducing mid-continent light goose populations. Assessing body condition of light geese harvested by various methods during the LGCO and examining species, sex and age composition of the harvest would provide insight to other impacts of harvest efforts to reduce populations. Such information could be used to help justify further, and perhaps more controversial action, in terms of reducing light goose populations.