Distributional shifts of wintering midcontinent greater white-fronted geese

Despite a historically large degree of philopatry to the Gulf Coastal Plains wintering area in the United States and Mexico, the midcontinent population of greater white-fronted geese (Anser albifrons) has demonstrated changes in their winter distribution in recent decades, warranting investigation into the timing and magnitude of change. We evaluated spatiotemporal patterns in winter band recovery distribution from 1974-2018 and midwinter waterfowl survey counts for midcontinent greater white-fronted geese. We used an overlap similarity index to compare annual winter band recovery distributions with a historical reference distribution of 1955-1974, followed by a changepoint analysis to assess the timing and magnitude of distributional change. Our analyses revealed a 2-stage shift in the distribution of winter band recoveries from midcontinent greater white-fronted geese that occurred following the 1994-1995 season and the 2009-2010 season. As a result, the spatiotemporal distribution of midcontinent greater white-fronted goose band recoveries can be explained in 3 distinct time eras: the historical era (1974-1995), the transitional era (1995-2010), and the current era (2010-2018). Patterns in midwinter waterfowl survey counts were consistent with changes in winter band recovery distributions, providing further support that midcontinent greater white-fronted geese have shifted their core winter distribution nearly 750 km northeast over the last 5 decades from the Gulf Coastal Plain to the Mississippi Alluvial Valley. Quantifying the timing and magnitude of this shift in winter distribution of midcontinent greater white-fronted geese provides clarity to previous patterns in and changes to harvest distribution and could be used to facilitate future decisions regarding harvest management, regulatory frameworks, and habitat conservation planning efforts.

Automated summary

The midcontinent population of greater white-fronted geese has shifted their winter distribution from the Gulf Coastal Plain to the Mississippi Alluvial Valley over the past five decades. This shift occurred in two stages, following the 1994-1995 season and the 2009-2010 season, and can be divided into three distinct time eras: historical era (1974-1995), transitional era (1995-2010), and current era (2010-2018). The changes in winter band recovery distribution and midwinter waterfowl survey counts support this shift.