Duck Breeding Habitat Selection

Female Scaup Lower Red Rock Lake

Biologists at the refuge study the preferences of waterfowl (Lesser Scaup) for selection of their breeding places. Are ideal breeding conditions preferred over previous successes at other locations and/or with other nearby female scaup?

 


Short Title: Duck Breeding Habitat Selection

Longer Title: How do Lesser Scaup choose habitats for breeding?

Actual Title: Behavioral cues surpass habitat factors in explaining prebreeding resource selection by a migratory diving duck

Authors: Shawn T. O’Neil a, Jeffrey M. Warren, John Y. Takekawa c, Susan E. W. De La Cruz,
Kyle A. Cutting, Michael W. Parker, Julie L. Yee

Short Description of Science Project:

For a diving duck like the Lesser Scaup, it is desired to find out if ideal local conditions (food availability, shelter, water, etc) at a breeding site influences their selection of breeding sites more or less than a need or desire to be close to others of the same species or even other ducks or if previous breeding success at the same location (having more ducklings survive) is more important. Having a model of this behavior would help wildlife managers prioritize projects to improve water fowl reproduction. Some other studies have shown that in migratory song birds, like the American Robin and Red-backed shrikes, returning to previous breeding areas and nesting sites is a common behavior thought to result in higher fitness of individual birds. This study seeks to find out if this applies to migratory diving ducks such as the Lesser Scaup.

Where was it done?

 

This study was conducted on and around Lower Red Rock Lake in the refuge. This is an area of variable wetlands containing favorable conditions (food and shelter) for the Lesser Scaup. The wetland supports some of the highest densities of breeding scaup in North America, with more than 12.32 scaup per square mile (7.7 per km2). The southwestern half of the complex is predominantly open-water habitat with interspersed islands of bulrush. The north and east extent of the complex is characterized by submerged aquatic vegetation with small, scattered, open-water ponds.

How was it done?

Female Lesser Scaup were captured, nasal-banded and/or radio-tagged using surgical implants shortly after arrival on the refuge. This was done at night with lighting from boats. About 30 females were fitted with radio transmitters for both the 2007 and 2009 study years. Nasal-marked females without transmitters that were marked during mid-May of each year numbered as follows: 72 (2005), 90 (2006), 81 (2007) and 90 (2008).

Various data were collected. Biologists watched birds forage to locate nests and then hiked/boated among the bulrush to find the nests. These were counted and a red-flag placed nearby. These nests were visited frequently until the fate of the nest was known (hatched, abandoned, destroyed, etc). Bird range and location was determined using triangulation methods from both radio-receivers mounted in trucks and hand-held directional antennas/receivers. Range habitat characterization (open water, vegetation, etc) was done using analysis of specific wavelength reflections from aerial survey sensor data. Water depth information was measured using hand-held GPS and measuring tapes. Density of female scaup were determined by manually counting nasal-banded females at several times during the study and plotting this information in relation to location. Collecting this data over 4 years and observing specific individual nesting sites allowed biologists to measure the affinity to previous year nesting sites.

Data collected from these activities were analyzed by biologists using numerous complicated (and academically accepted) statistical analysis techniques designed to fill in gaps of missing data, and to provide correlation over space and time among the various data types collected.

The main thrust of the project was to identify where the scaup nested in relation to various parameters, like water depth, other scaup, vegetation cover and weather related data.

Results of Science Project

 

Correlation made from the data suggest that female scaup are more influenced by the nearness to other nesting scaup and the prior year nesting success than specific breeding habitat advantages. Large differences in water levels, like that in a drought, greatly influence the location of scaup nesting sites due to the requirement for scaups to be near submerged vegetation.

Often, conservation management within a refuge focuses on proper breeding habitat conditions. However, prebreeding habitat selection within home ranges by scaup females in this study was strongly influenced by proximity to areas of successful reproduction of the scaup during the prior year(s). This legacy effect of reproductive success could result in a model showing better reproductive success based on ideal habitat conditions, but with a lag of at least 1 year due to the influence of prior year memories of success by the birds. Thus, a good conservation model could be improved by a better understanding of how the behavior of ducks to return to the same place each year affects breeding success.

Duration of Science Project: The field work for this project began in 2005 and lasted through 2008. Analysis continued through 2012.

 

Published by: Elsevier, January 2014

 

Link to the Original Paper:  PDF