Dennis G. Jorde
Christine M. Bunck
G. Michael Haramis
1993
<p>Low annual survival of hatching-year (HY) females is a critical management concern for canvasbacks (<i>Aythya valisineria</i>), and may contribute substantially to reduced reproductive potential and the male-biased sex ratio of the species. To evaluate the contribution of mortality on a traditional wintering area to low annual survival, we estimated survival rates of HY female canvasbacks during 3 winters (1987-89) on Chesapeake Bay. We implanted radio transmitters in 204 HY and 44 after-hatching-year (AHY; 1989 only) female canvasbacks and tracked them from mid-December to early March. Ten-week survival rates did not differ (<i>P</i> > 0.05) among years for HY females; estimates ranged from 0.833 to 0.930 and averaged 0.887. Of 17 mortalities recorded for HY females during the 3-year study, 14 of 15 dated deaths occurred during the duck hunting season (first 3 weeks of the study), even though the hunting season on canvasbacks was closed. As a result, survival rates were lower during hunting versus posthunting periods (<i>P</i> <span>≤</span> 0.05 for 2 of 3 yr). Illegal hunting was the single largest source of mortality for HY females. Shot ducks accounted for a loss of 4% and suspected crippling losses (ducks scavenged by shoreline predators) may have increased hunting-associated losses to as high as 7%. In 1989, no deaths were observed for AHY females, and their survival was higher <i>(P</i> = 0.02) than HY females. High winter survival for HY females indicates that substantial mortality occurs at some other time of the annual cycle.</p>
application/pdf
10.2307/3809077
en
Wiley
Survival of hatching-year female canvasbacks wintering on Chesapeake Bay
article