Survival and recovery rates of webless migratory game birds

Principal Investigator: Todd Arnold.

Graduate Students: Hannah Specht, Seth Stapleton.

Research Associate: Cristina de Sobrino

Status: Completed. Project extended from May 2013 to Jul 2014 and involved analysis of band recovery data from American coots (Fulica americana), clapper rails (Rallus crepitans), sandhill cranes (Grus canadensis), and Wilson’s snipe (Gallinago delicata). 

This project had two major objectives. The first was to summarize existing band recovery and recapture data for webless migratory game birds to determine which species met necessary sample sizes for survival analysis. For sora (Porzana carolina), Virginia rail (Rallus limicola), king rail (Rallus elegans), and purple gallinule (Porphyrio martinica), recovery data were too sparse, and low encounter rates suggested that no reasonable amount of future banding effort would ever lead to sufficient samples. But for American coots, common moorhens (Gallinula chloropus), clapper rails, sandhill cranes, and Wilson’s snipe, we were able to generate some of the first survival estimates based on statistically robust methods [reliable estimates have already been published for mourning doves (Zenaida macroura), white-winged doves (Zenaida asiatica), band-tailed pigeons (Patagioenas fasciata), and American woodcock (Scolopax minor)].

Estimated annual adult survival using year-round bandings and recoveries of dead birds (shot plus other mortality sources) was 0.884 (SE 0.006) for sandhill cranes, 0.583 (SE 0.008) for American coots, 0.508 (0.025) for clapper rails (Gulf and Atlantic Coast populations only), and 0.653 (SE 0.020) for Wilson’s snipe. Juvenile survival was 0.325 (SE 0.025) for American coots, 0.368 (SE 0.070) for clapper rails, and 0.372 (SE 0.077) for Wilson’s snipe; we could not obtain reliable estimates of juvenile survival for sandhill cranes. Trend models were deemed unreliable for survival rates given sparse data, but recovery rates of adult sandhill cranes have increased through time, whereas recovery rates of the remaining three species have declined.