J.-F. Giroux
G. Gauthier
J.D. Nichols
J.E. Hines
A. Bechet
2003
<p><span>1. Human-induced disturbance such as </span>hunting<span> may influence the migratory behaviour of long-distance migrants. In 1999 and 2000 a </span>spring<span> hunt of </span>greater<span> </span>snow<span> </span>geese<span> Anser caerulescens atlanticus occurred for the first time in North America since 1916, aimed at stopping population growth to protect natural habitats. 2. We evaluated the impact of this hunt on the staging </span>movements<span> of </span>geese<span> along a 600-km stretch of the St Lawrence River in southern Quebec, Canada. 3. We tracked radio-tagged female </span>geese<span> in three contiguous regions of the staging area from the south-west to the north-east: Lake St Pierre, Upper Estuary and Lower Estuary, in </span>spring<span> 1997 (n = 37) and 1998 (n = 70) before the establishment of </span>hunting<span>, and in 1999 (n = 60) and 2000 (n = 59) during </span>hunting<span>. 4. We used multi-state capture-recapture models to estimate the </span>movement<span> probabilities of radio-tagged females among these regions. To assess disturbance level, we tracked </span>geese<span> during their feeding trips and estimated the probability of completing a foraging bout without being disturbed. 5. In the 2 years without </span>hunting<span>, migration was strongly unidirectional from the south-west to the north-east, with very low westward </span>movement<span> probabilities. </span>Geese<span> gradually moved from Lake St Pierre to Upper Estuary and then from Upper Estuary to Lower Estuary. 6. In contrast, during the 2 years with </span>hunting<span> westward </span>movement<span> was more than four times more likely than in preceding years. Most of these backward </span>movements<span> occurred shortly after the beginning of the hunt, indicating that </span>geese<span> moved back to regions where they had not previously experienced </span>hunting<span>. 7. Overall disturbance level increased in all regions in years with </span>hunting<span> relative to years without </span>hunting<span>. 8. Synthesis and applications. We conclude that </span>spring<span> </span>hunting<span> changed the stopover scheduling of this long-distance migrant and might further impact population dynamics by reducing prenuptial fattening. The </span>spring<span> hunt may also have increased crop damage. We propose that staggered hunt opening dates could attenuate secondary effects of such management actions.</span></p>
application/pdf
10.1046/j.1365-2664.2003.00812.x
en
British Ecological Society
Spring hunting changes the regional movements of migrating greater snow geese
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