Habitat Selection for Nest Cups of the Pacific Golden Plover (Pluvialis fulva) in Nome, Alaska
Pacific golden plover (Pluvialis fulva) nest in western Alaska and winter in Hawai‘i and the insular Pacific. Populations that breed in the Russian far east winter in the western Pacific and in coastal areas of Southeast Asia, Australia, and New Zealand. Alaska natives refer to the Pacific golden plover as the tuusiik. (Eskimos name animals by the sound they make.) In Hawai‘i the Pacific golden plover is known as kolea, which translates as "one who takes and leaves," an obvious reference to their migratory habitats.Most Pacific golden plover are territorial in their Hawaiian wintering grounds. High return rates are typical of these species (Johnson et al., 1981). Territorial birds reoccupy the same territories each winter, and non-territorial individuals frequent the same general area annually. Obtaining a territory is an adaptive characteristic, as it allows them to control access to essential food resources. A territory occupied on a daily and annual basis may increase the bird‘s ability to avoid predation by knowing the best escape routes. In 1999, I conducted a study on the Big Island of Hawai‘i regarding the Pacific golden plovers‘ territorial behavior. They were found to utilize their territory primarily during the morning hours, but could be seen there throughout the day if there was no disturbance. Weather was not found to be a factor determining their presence or absence.
Studies of marked Pacific golden plover on the Seward Peninsula in western Alaska show that males return to the same breeding territory, but females were much less site-specific (Johnson et al., 1993). On the Taymyr Peninsula of the Russian far east, three out of four nesting Pacific golden plover (sexes not indicated) banded by Underhill et al. (1993) returned in the following year, and a female marked by Tomkovich and Vronski (1988) nested at the same site in two consecutive seasons. From the winter of 1999 into the spring of 2000, I conducted another study on the Pacific golden plover, this time examining the male-to-female ratio on lawn habitats such as soccer fields and backyards. I found that there was a highly significant difference in the amount of males versus females. The males seemed to outnumber the females by 3 to 2. There is still no conclusion as to whether the gender ratios are actually skewed, or if females tended to frequent the non-lawn habitats, such as dirt roads and agricultural fields.
Since the sixth grade, I have created science fair projects annually on the Pacific golden plover, but my interest in the plover goes far deeper. At a very young age I had noticed a bird in the back of my yard every day of the winter season. During the summer I would never see this mysterious bird, and began to wonder why. That question prompted the first of my science fair projects on the Pacific golden plover‘s migratory behavior. From then on, my interest in the Pacific golden plover, and other, similar species, has grown tremendously, and has driven me to my newfound exploration in Nome, Alaska.
On a yearly basis, Mr. Phil Bruner, a biologist at Brigham Young University, Hawai‘i, and his wife Andrea, perform observations on the Pacific golden plover in Nome, Alaska, during the early summer months. Mr. Bruner is my mentor, assisting me with my research on the plover. He encouraged me to advance my studies on the Pacific golden plover by traveling to Nome with him and his wife to aid in their ongoing research during the summer of 2000. I finally made the decision to go, at the expense of forsaking personal trips, and am extremely glad that I did. I had never been to Alaska, let alone Nome, and believed it would be an exciting expedition.
The scenery of Nome was beautiful (Figure 1). The air was crisp and clean, no signs of pollution or smog; crystal-clear water flowed through side streams. Snow from the past winter lay on the pristine hills and mountains. Human contact was minimal; the ground was touched only by passing wildlife. Driving down the long and dusty road, every bump on the path was a new adventure, waiting to be explored. Musk oxen, foxes, and moose walked nonchalantly across the tundra, barely noticing the dusty Ford Explorer forging past them (Figure 2). Never have I seen such vast, undeveloped land acreage. It was an exhilarating feeling for me at the moment—the true beauty of Alaska, the last frontier. Life history research on the Pacific golden plover has produced much information, including evidence of distinct differences in topographic and vegetative requirements at breeding sites. A nest cup is a shallow depression filled with lichens and moss. The cup may be reused in subsequent breeding seasons (Connors et al., 1993; Johnson and Connors, 1996; Johnson et al., 1993). One area where data is still needed is on whether or not this species randomly or deliberately selects the actual sites where each plover places its nest cup each season. Until now, no quantified study of the habitat immediately surrounding the nest cups of this species had ever been attempted. Therefore, the purpose of my study was to examine a one-meter-square area around each nest cup and determine what percentage of this plot was composed of vascular and non-vascular vegetation, or non-living material.As I explored previously marked sites of Pacific golden plover nest cups on the tundra of Nome (Figure 3), a photograph was taken to identify general habitat features: vascular plants, non-vascular plants (lichen, moss), and non-living material (rocks, soil).
Twenty-one nest cup sites were used in this study. Once the exact location of the nest was determined, all artificial indicators used to mark the area were temporarily removed. A string was used to mark a one-meter area around each nest cup. Information regarding nest cup identification was written on an index card and placed on one side of the quadrant (Figure 4). A photograph was taken of the area with both a digital and 35-millimeter camera. Once this step was completed, the string and index card were carefully removed and all markers were replaced. If a clutch of eggs was present in the nest, extreme caution was used when placing and removing markers in order to minimize the scent of human presence, which might attract predators.
Each photograph was digitally enhanced and was overlapped with a grid of 100 squares. I examined each photograph with the dot-method test. I used a transparent square the size of each computer-grid square, with four equally spaced dots marked on the surface, and placed this square on the computer screen. I chose two of the four dots randomly, and the substrate immediately beneath each chosen dot was recorded. The possible substrate categories were: vascular plants, non-vascular plants, and non-living material (rocks, soil). All of the 100 grid squares were examined (Table 1) . The percentage of vegetative type or non-living material was calculated ( Table 2 and Figures 5-6). I applied a t-test to the data in order to determine if there were significant differences in the percentage of each substrate.The data analysis indicated that vascular plants dominated at six cups, non-vascular plants at 13 cups, and non-living material (rocks, soil) at two cups. When the percentages of vascular and non-vascular plant data were compared across at 21 nest plots, using a t-test, no significant differences were found (p0.01). By contrast, when either vascular plant or non-vascular plant coverage was compared to non-living coverage data for all 21 nest plots, both vascular and non-vascular data were significantly greater (p0.05) than non-living cover data. These results suggest that Pacific golden plover may prefer a vegetation cover surrounding the nest to non-living material (rocks, soil) in the immediate (one-square-meter) area.
There are several possible reasons for this finding. The abundance and distribution of vascular and non-vascular plants to non-living material throughout the breeding territory may be similar to the area immediately around the nest cup. If this is true, then the type of cover immediately around the nest is just a reflection of what is available throughout the territory. This hypothesis would then argue that the location of the nest cup is strictly random. To date, the percentage of cover and the distribution of vascular, non-vascular, and non-living material has not been determined for any of the breeding territories containing the nest cups in this study. On another expedition to the nesting site, several nest cups could be surveyed to characterize these territories ecologically. Data from these surveys could be used to determine if the plover are randomly or deliberately selecting the location of their nest cups.
If the plovers‘ preference for plant cover around the nest is not just a reflection of what is available, then another hypothesis needs to be offered. Perhaps Pacific golden plover prefer to place their cups in spots with more vegetation rather than in areas with abundant non-living material (rocks, soil) because the vegetation provides better camouflage for the nest. In those cases where non-vascular plants dominate the area about the nest, the white lichens may provide camouflage for the light-colored eggs.
Finally, this study, like most research, only opens doors to more questions. For instance, how do the results compare with other plover in the same genus? What are the evolutionary implications of random versus active selection in the location of the nest cup?
Connors, P.G., B.J. McCaffery, and J.L. Maron. "Speciation in golden-plovers Pluvialis dominica and P. fulva : Evidence from the breeding grounds." Auk 110 (1993): 9-20.
Connors, P.G., P.L. Bruner, and J.L. Maron. "Breeding ground fidelity and mate retention in the Pacific Golden-Plover." Wilson Bulletin 105 (1993): 6067.
Johnson, O.W. and P.G. Connors. "American Golden-Plover ( Pluvialis dominica )," and "Pacific Golden-Plover (Pluvialis fulva )." In The Birds of North America (A. Poole and F. Gill, eds.). Academy of Natural Sciences, Philadelphia, and the American Ornithologist‘s Union, Washington D.C., No. 201202 (1996).
Johnson, O.W., P.M. Johnson, and P.L. Bruner. "Wintering behavior and site faithfulness of Golden-Plovers on O‘ahu." Elepaio 41 (1981): 123130.
Tomkovich, P.S., and N.V. Vronski. "The bird fauna of Dikson vicinity, northern Taymyr" (in Russian). In Birds of Populated Territories (O.L. Rossolimo, ed.). Moscow: Moscow University Press (1988): 3977.
Underhill, L.G., R.P. Prys-Jones, E.E. Syroechkovski Jr., N.M. Groen, V. Karpov, H.G. Lappo, M.W.J. Van Roomen, A. Rybkin, H. Schekkerman, H. Spiekman, and R.W. Summers. "Breeding of waders (Charadrii) and brent geese (Branta bernicla bernicla) at Pronchishcheva Lake, northeastern Taymyr, Russia, in a peak and a decreasing lemming year." Ibis 135 (1993): 277292.
I would like to sincerely thank my research mentors, Mr. Phil Bruner and Dr. Robert Winget of Brigham Young University, Hawai‘i. I am very appreciative of Mr. and Mrs. Phil Bruner, who allowed me to accompany them on their expedition to Alaska to further my research on the Pacific golden plover. I am truly grateful for all their assistance and ongoing support.
Copyright © 2002 American Museum of Natural History
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