| Rodents abundance evaluation: |
low
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Breeding conditions:
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A very dry winter, a thin winter snow pack, and a warm April resulted in extensive snow-free tundra when breeding shorebirds arrived (Rock Sandpiper 23 April; Ruddy Turnstone 28 April; Black-bellied Plover 29 April; Western Sandpiper, Dunlin 30 April; Black Turnstone, Red-necked Phalarope, Wilson's Snipe 1 May; Bar-tailed Godwit 2 May) and when migrants began passing through (Semipalmated Sandpiper 30 April; Pacific Golden-Plover 1 May; Long-billed Dowitcher, Greater Yellowlegs, Red Knot 3 May; Bristle-thighed Curlew 5 May).
Breeding Shorebird clutch initiations at KFS were early in 2004. Rock Sandpipers began initiating clutches during the first week of May, and Western Sandpipers and Ruddy Turnstones began initiating clutches during the second week of May. The first Western Sandpiper nest in 2004 was initiated on 11 May, which tied the earliest recorded initiation date for this species at KFS (2003) and was nearly a week earlier than all prior years (1998-2002). The first Dunlin nest was initiated on 12 May, and the first Red-necked Phalarope clutches were initiated during the third week of May. Although Bar-tailed Godwit and Black-bellied Plover nests were monitored at KFS, we did not discover nests of either species until 7 and 26 June, respectively. We have no data to suggest that the former was a particularly early nest, and the latter certainly was not.
In 2004, the combined frequency of all mammalian predator observations (i.e., Arctic Fox, Red Fox, and Mink) was the highest during the study. During 10 weeks of study at KFS, Arctic Fox, Red Fox, and Mink were observed on 14, 15, and 18 days, respectively. Long-tailed Jaegers are fairly common at this site, and a minimum of one pair of Long-tailed Jaegers bred at KFS in 2004. There was no obvious correlation, however, between the frequency of predator observations and wader nest success. For example, during the year of lowest sandpiper nest success (2002), we made less than half as many predator observations as in 2004, and in the year of most frequent predator observations (1999), sandpipers had average nest success. The number of observations of mammalian predators on our study site has not been correlated with our qualitative assessment of rodent abundance.
Western Sandpipers: Basic methodologies (1998-2004) include two observers surveying a 16ha long-term study-plot daily from early May through late July for banded birds, nests, and broods. Adults and chicks are banded with unique color combinations at the nest, and the location and behavior of banded birds is recorded daily. The locations of discovered nests are mapped and nests are monitored through hatch, predation, or abandonment. After hatch, WESA parent(s) and broods are resighted (brood location mapped, parent and chick behaviors recorded) once (1998-2002) or twice (2003-2004) daily through fledge, predation, or abandonment.
In 2004, we located and monitored a total of 53 nests on the 16 ha study-plot. Thirty-six of these nests were initial nesting attempts, and for one nest we were unable to determine whether this represented an initial nesting attempt as neither attending adult was banded. Thirteen males and 11 females attempted reproduction after initial clutch loss (re-nested) in 2004. Of the 13 males to receive secondary clutches, one male attempted reproduction a third time and another male attended a total of four nests. We have observed individual females producing three clutches within a single breeding season near our study site (1999 n=1, 2003 n=2, 2004 n=2); however, only one of these females placed its third nest of the season within our long term study-plot (2003). Based on initial nesting attempts, we estimate the density of WESA on the long-term study-plot in 2004 was 2.25 pair/ha, and apparent nest success (i.e., percent of known nests successfully hatching >1 chick) among first nests in 2004 was 17% (Mayfield nest success = 0.19, 95% CI = 0.13-0.27, n = 36), and at least one chick fledged from all hatched nests. We estimated Mayfield nest success for all nests, including renesting attempts, on the main plot = 0.16 (95% CI = 0.11-0.22, n = 53).
In 2004, we initiated a larger scale portion of the study, by establishing 29 outlying-plots (8ha/plot) across 29 km2 of WESA breeding habitat near KFS. Outlying-plots were surveyed once and in random order, during the portion of the season/daily cycle when male display flights are most common (15-31 May, 11:30-18:00 AKST, unpublished data). During rapid surveys of outlying-plots, a single observer systematically walked back-and-forth across the plot to its lengths-end (30 min/plot), mapping the locations of all WESA, and noting behaviors and pairing status. We also conducted rapid surveys on half of the long-term study-plot (8ha) on the same days that out-lying plots were surveyed. During rapid surveys on outlying-plots, we observed an average of 11.4 WESA/plot (range 0-31, 1.4 WESA/ha). During rapid surveys on half of the long-term study-plot (n=16 surveys, area equivalent to outlying-plots, 8ha), we observed an average of 19.3 WESA/survey (range 9-28, 2.4 WESA/ha).
Rock Sandpipers. During 1999-2000, four adult ROSA, from three pairs, were banded at KFS. The pair banded in 1999 has returned and bred together every year since. During 2003, we banded 10 adult ROSA from five pairs at KFS, and all 10 of these individuals were resighted at KFS in 2004. During 2004, we banded an additional three adult ROSA, from 2 pairs. During 2004, we located and monitored nine ROSA nests from six pairs in a 48ha area in and around KFS (0.13 pair/ha). Half of all ROSA pairs re-nested after initial clutch loss (3/6). Three of nine ROSA nests successfully hatched young (2-initial nesting attempts, 1-renesting attempt). Young successfully fledged (attained flight) from one ROSA brood, and another brood survived for at least 11 days post-hatch before we terminated observations. The third ROSA brood at KFS was likely taken by a Long-tailed Jaeger eight days post-hatch.
Dunlin. This was the first field season investigating the breeding ecology of Pacific Dunlin. We surveyed three wet meadows for a total of 72 hectares. During nesting, each site was visited, at a minimum, every three days. Nests were found primarily through behavioural observations although each site was rope-dragged at least once during peak incubation. Once found, we attempted to trap and color band both adults. Each nest was visited regularly to check its status (active, depredated, abandoned, or hatched). If a clutch hatched the brood was searched for every one to two days and if found its location and which parent was attending was recorded. If we were unable to find a brood for more than two visits they were assumed dead or emigrated.
The first Dunlin was observed on April 30. The earliest nest was initiated on 12 May and the last was initiated on June 30. We located and monitored a total of 59 nests, and trapped and color banded 67 adults. We estimated that 42 of the nests found were first attempts, 14 were first renest attempts and three were second renest attempts. At a minimum, the nesting density was 0.58 pair/ha. The average incubation period was 22.1 days. Estimated Mayfield nest success was 36% (95% CI= 23-39%) and Mayfield fledgling success (the probability that nests that hatched fledged young) was 73% (95% CI= 58-91%).
We documented double brooding for the first time in North American Dunlins. On two occasions we had a female successfully hatch a clutch with one male then desert the brood and lay another clutch with a second male.
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