Graduate Thesis Or Dissertation
 

Time budget and habitat use patterns of marbled godwits (Limosa fedoa beringiae) breeding on the Alaska Peninsula

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/mc87pv83j

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  • Diurnal time budgets and habitat use patterns of breeding Ugashik marbled godwits (Limosa fedoa beringiae) were studied on the north-central portion of the Alaska Peninsula during spring and summer 1995-1996. Marbled godwits were observed from blinds and behaviors were described for the four phases of the breeding season: pair-formation, egg-laying, incubation and post-hatching. During pair-formation, males spent the majority of time performing flight displays (40.2%), most notably the ceremonial flight (30.7%). Males spent 34.3% of the egg-laying period guarding their mates probably to reduce the threat of cuckoldry. Females incubated during the daytime and males incubated at night. Off-duty males were engaged in maintenance activities (49.4%) or were alert/erect (22.7%). Four marbled godwit nests and the first newly hatched, downy marbled godwit chicks ever recorded in Alaska were found within the study site. One parent guarded the chicks which allowed the other to forage in nearby wetlands. Males performed male-exit flight as they prepared to depart for coastal staging lagoons approximately three weeks after their chicks hatched. Interspecific and intraspecific hostility peaked during the post-hatching period although aggressiveness towards neighboring shorebirds decreased. Godwits may benefit from the aggressive nature of some neighboring shorebirds and more timid species may receive a similar benefit from nesting close to godwit semi-colonies. The scattering of nests in loose semi-colonies may reduce predation by offering both nest concealment and group defense. Cover types and microhabitat characteristics were compared between sites used by marbled godwits ("present") and paired sites where no godwits were observed throughout the breeding season ("absent"), and among sites used for broodrearing, foraging, ground display and nesting. Logistic regression models predicted the probability of godwit occurrence or the probability of a godwit broodrearing, foraging, displaying or nesting based upon significant site features. Results indicate that different cover types were used for broodrearing, foraging, ground display and nesting, and cover types differed between present and absent sites. Microhabitat characteristics were different between present and absent sites, and they varied among the different use sites. The odds of finding a godwit at a site or the odds of finding a godwit broodrearing, foraging, displaying or nesting changed with changes in the significant microhabitat characteristics. As the percent shrub cover increased the odds of finding a brood or a nest increased 2.65-fold and 1.95-fold, respectively. The vegetation at broodrearing sites was taller (1.6 dm) than the vegetation at the other use sites, while the vegetation at nest sites was considerably shorter (1.3 dm) and denser. The probability of finding a godwit foraging increased with increasing forb cover and water depth, and decreasing shrub and moss cover and site roughness. Godwits used the periphery of wetlands for ground display. These grassy areas were typically transition zones between the wetland itself and the drier shrub communities.
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