Abstracts

Download a PDF containing all abstracts from the conference.

P.1-07: Investigating wing molt ecology of gadwall and mallards nesting in the Suisun Marsh of California

Presented by Jeffrey Kohl - Email: jkohl@usgs.gov

We monitored postbreeding movements of hen gadwall (Mareca strepera) and hen mallards (Anas platyrhynchos) nesting in the Suisun Marsh of California to determine wing molt chronology and molt site selection during 2015-2018. GPS-GSM backpacks were attached to hens nesting on Grizzly Island State Wildlife Area and private duck clubs within the Suisun Marsh and bird locations received daily via the GSM network. We were able to acquire molting chronology information for 49 gadwall and 77 mallards as well as determine molting sites for 52 gadwall and 111 mallards. Greater than 55% of the marked gadwall hens molted within two watershed basins during the study; the Lower Klamath (27%) and Upper Klamath Basin (31%) in northeastern California and southern Oregon, respectively. Mallards molted in primarily six basins in California and Oregon which included the Suisun Marsh (31%), Sacramento-San Joaquin Delta (10%), Butte Basin (12%), Colusa Basin (12%), Lower Klamath Basin (11%), and the Upper Klamath Basin (12%). Molt start date for gadwall ranged from July 10th Sept 23rd with a mean start date of August 26th ( 4.60). Molt start date for mallards ranged from June 16th October 8th with a mean start date of August 25th ( 4.11). Gadwall had a mean molting duration of 34.44 days ( 3.01) and mallards had a duration of 40.53 days ( 2.96). Gadwall and mallards predominantly used permanent marsh (90.38% and 63.06%, respectively) as their preferred molting habitat. Results suggest that these high-use molting areas utilized by California breeding hen gadwall and mallards could benefit from management actions meant to improve postbreeding survival and increase waterfowl populations breeding in California.
Session: Poster Session 1 (Tuesday, August 27, 19:00 to 21:00)