Survival and habitat selection of Wood Duck hens and broods at Long Point, ON

Principal Investigator:
Matt Dyson, MSc Candidate

Supervisors:
Dr. Scott Petrie, Long Point Waterfowl Executive Director
Dr. Hugh Henry, Western University
Ted Barney, Long Point Waterfowl
Michael Schummer, Long Point Waterfowl

 

Wood ducks are managed throughout their breeding range using nest box programs. The success of these programs has been researched extensively and is well documented; however, continued research is necessary to evaluate these programs and make them more cost-effective. For example, the contribution of a nest box program (i.e., production) may be overestimated if post-hatch survival is low as a result of poor brood-rearing habitats. Therefore, knowledge of survival and habitat selection for wood ducks post-hatch is critical to refining future management plans. Additionally, identification of potential ecological sinks, where survival is low, could greatly contribute to increasing survival during the brood-rearing period for both wood ducks, and other waterfowl species, by improving the amount of quality habitat available.

The goal of our study was to gain a better understanding of brood-rearing ecology for wood ducks produced from nest boxes at Long Point. Our objectives were to: 1) determine how wood duck hens and ducklings moved throughout the landscape post-hatch, 2) determine what habitats wood duck hens and ducklings use throughout the brood-rearing period, and 3) quantify survival of wood duck hens and ducklings during the brood-rearing period. We predicted that movement and habitat selection of wood ducks with broods would be different from those without broods (i.e., lost broods), as a result of specific dietary requirements of ducklings and necessity for increased predator avoidance. We also predicted that habitat selection would be affected by hen age/experience (ASY vs. SY), hatch date (May vs. June), and nest site location (Big Creek vs. Other). Additionally, we predicted brood and duckling survival would be a function of hen age and mass, hatch date, initial brood size, temperature, and precipitation.

We completed the study at Long Point, Ontario, primarily along Big Creek where there was an established nest box program (n = 304 boxes). Nest boxes were monitored twice monthly to determine occupancy from April – July. We candled eggs to determine their stage of incubation and trapped hens at > 20 days incubation using modified nest box traps. A prong and suture radio transmitter was attached to hens along with an aluminum leg band. Following marking, hens were monitored daily to determine hatch date, and then tracked daily using a truck mounted null-peak antenna to 30 days post-hatch. Hens were visually observed at 15 and 30 days post-hatch to determine duckling survival.

Brood-rearing hens selected swamp, scrub-shrub, and emergent marsh habitats, showed no selection for open water and forest habitats, and avoided urban and agricultural habitats. Additionally, selection did not differ by age or hatch date, but it differed by nest location with hens along Big Creek having weaker selection for swamp habitat relative to hens that nested off Big Creek. Hen survival was high during brood-rearing (Ŝ = 0.90, 95% CI = 0.81 – 1.0). Conversely, brood (Ŝ = 0.47, 95% CI = 0.33 – 0.69) and duckling (Ŝ = 0.18, 95% CI = 0.14 – 0.22) survival were low; however, similar to estimates from southern areas. Brood survival was best explained by a model containing hatch date and precipitation covariates, where the risk of brood mortality increased by 8% for every day of later hatch date and decreased by 5% for every cm increase in precipitation over the brood rearing period. Duckling survival was best explained by a model containing hen age and mass, and initial brood size covariates. The risk of duckling mortality was 53% less for second year (SY) hens than after second year (ASY) hens, decreased by 1% for every gram increase in mass, and increased by 15% for every additional duckling in a brood.

Our study provides a better understanding of habitat selection and survival of wood ducks breeding in riverine and wetland habitats of the Great Lakes. We recommend waterfowl managers direct habitat conservation efforts towards the provision of swamp habitats for areas where nest box programs are used. We also recommend future research identify optimal nest box densities that balance the production of wood duck ducklings from nest boxes with the carrying capacity of the habitat to ultimately increase recruitment.

 

Project Sponsors and Partners

Fred Mannix and Bill Turnbull (The Bayou Club)
Long Point Region Conservation Authority
Canadian Wildlife Service
Ontario Ministry of Natural Resources
Long Point Waterfowl
Ducks Unlimited Canada
Wildlife Habitat Canada
Ontario Power Generation
Environment Canada
Kenneth Molson Foundation
Toronto Zoo
Ontario Federation of Anglers and Hunters
Private Landowners
Adopt A Hen Sponsors (see Adopt-A-Hen page)
Waterfowl Research Foundation
Husky Energy

Comments are closed.