Body Mass Dynamics, Stopover Duration, and Habitat Conditions for Migrant Shorebirds in the Southwest Lake Erie Marsh Region
A Graduate Defense Seminar will be presented by Keith Norris, MS Candidate in Fisheries and Wildlife Science, on Monday (8/3) at 10:30 a.m. in 333 Kottman Hall. Keith will present Body Mass Dynamics, Stopover Duration, and Habitat Conditions for Migrant Shorebirds in the Southwest Lake Erie Marsh Region.
Wetland and coastal areas along shorebird migration routes provide critical stopover habitat and food resources for shorebirds to rest and replenish necessary fat reserves to complete migration. Resource limitations can cause energetic shortfalls that prevent shorebirds from completing migration in good body condition, potentially impacting survival and contributing to population declines. I conducted research at an inland stopover site to analyze within and cross-seasonal changes in shorebird body mass and to investigate relationships of body mass dynamics to stopover duration, food availability, and habitat conditions to gain insights on potential habitat limitations encountered by migrating shorebirds. Analysis of within-season recaptures (n = 783) indicated that shorebirds gained body mass during autumn and generally maintained body mass during the spring in the LEMR. Autumn minimum stopover duration estimates were doubled to calculate full stopover durations of 12 days for semipalmated sandpipers (n = 301), 13 days for short-billed dowitchers (n = 69), 14 days for pectoral sandpipers (n = 35), and 16 days for least sandpipers (n = 281). Rates of body mass gain were 0.4 g/day for least sandpiper, 0.6 g/day for semipalmated sandpiper, 1.1 g/day for pectoral sandpiper, and 1.5 g/day for short-billed dowitcher over the full estimated stopover duration in autumn. Habitat conditions varied between and within seasons based on weather patterns and wetland management activities. Food resources were highly variable across all seasons and ranged from 15.04 kg/ha (95%CL ±10.57) in spring to 30.03 kg/ha (95% CL ±13.44) in autumn. My estimated rates of body mass gain, full stopover duration, and food resource levels applied to the Upper Mississippi River and Great Lakes Region Joint Venture’s bioenergetics model increased estimated foraging habitat requirements for four species by 35.6% in order to maintain population levels.