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Summary
of fauna studies: |
Investigators: Richard Lanctot, U.S. Fish and Wildlife Service; Bart Kempenaers Max Planck Institute for Ornithology
In 2006, we conducted the fourth year of a long-term shorebird study at Barrow, Alaska (71.29øN, 156.64øW). The objectives of this study are to (1) collect baseline data on arrival date, nest initiation and effort, clutch and egg size, and hatching success of arctic-breeding shorebirds, (2) to establish a marked population of as many shorebird species as possible that would allow us to estimate adult survival, mate and site fidelity, and natal philopatry, and (3) to relate weather, predator and prey abundances to shorebird productivity. Data on demographic parameters are vitally needed to understand why many shorebirds are declining.
We located and monitored nests in six 36-ha plots in 2006. All six plots are the same as those sampled in 2005. We used the same search intensity and methodology as in 2004 and 2005. The breeding density of all shorebird species on our study area was 52.1 nests/km2 in 2003, 66.6 in 2004, 63.0 in 2005, and 150.5 in 2006 (overall average density across years was 83.0). The exceptionally high density of nests in 2006 far surpassed previous years. As in 2005, our ability to find nests was probably enhanced by a fox removal program that allowed many nests to survive through to hatching (see below), giving us more time to find the nests. While this may partially explain the high nest densities, it seems likely that the high shorebird numbers are somehow related to the extremely high lemming, Snowy Owl and jaeger numbers. Indeed, lemmings numbers were the highest documented since the early 1990s when Denver Holt and his crew began systematically trapping them on an annual basis.
In 2006, we recorded the highest breeding density of the four most abundant shorebird species in the four years of our study. These included Red Phalarope (50.5 nests/km2), Pectoral Sandpiper (48.2), Dunlin (17.6), and Semipalmated Sandpiper (8.3). We also had record densities of Long-billed Dowitchers (11.1), Buff-breasted Sandpipers (8.3), American Golden-plovers (2.8), and Red-necked Phalarope (3.2). A total of 325 nests were located on our plots and another 92 nests were found outside the plot boundaries. Nests on plots included 104 Pectoral Sandpiper, 109 Red Phalarope, 38 Dunlin, 18 Semipalmated Sandpiper, 24 Long-billed Dowitcher, 7 Red-necked Phalarope, 6 American Golden-plover, and 1 Baird's Sandpiper. For the first time since the beginning of this study, we located Buff-breasted Sandpiper nests on the tundra plots in 2006 (n=18). Western Sandpiper and White-rumped Sandpipers were not observed on our plots in 2006, and have only been documented nesting in 2004.
The first shorebird clutch was initiated on 3 June and the last on the 3 July in 2006 (on or within 1 day for both dates in prior years). Peak initiation date was the 12 June and median initiation date was the 15 June; this is within 1-2 days of median dates in earlier years. Median nest initiation dates for the more abundant species were the 11 June for Dunlin, 12 June for Semipalmated Sandpipers, 15 June for Red Phalarope, and 16 June for Pectoral Sandpipers. This pattern is similar to prior years. Predators destroyed only 8.3% of the nests in 2006 compared to 11.2% in 2005, 67.9% in 2004, and 42.6% in 2003. Across the more abundant species, hatching success (# hatching at least one young/total number of nests) was highest in Pectoral Sandpipers (90.4%, N = 94), followed by Red Phalarope (86.6%, N = 103), Semipalmated Sandpipers (93.6%, N = 29), and Dunlin (85.7%, N = 42). These numbers are even higher than in 2005 when predator removal appeared to substantially increase nest success. Alternative food sources in the form of high lemming abundance may have further enhanced shorebird hatching success, although other factors may be involved. A comparison across study plots indicated that hatching success was greater than 90% in plots 2 and 3, greater than 80% in plots 5 and 6, and equaled 72.7% in plot 8.
In 2006, we captured and color-marked 342 adults and 707 young. These numbers are about two times higher than 2005 captures and three times higher than 2003-2004 captures. Thirty adults (mostly Dunlin and Semipalmated Sandpipers) captured in 2006 had been banded in a prior year. Adults captured included 91 Dunlin, 72 Pectoral Sandpipers, 61 Semipalmated Sandpipers, 60 Red Phalarope, 29 Long-billed Dowitchers, 13 American Golden-plovers, 13 Buff-breasted Sandpipers, and one each of Baird's Sandpiper, Red-necked Phalarope and Western Sandpiper. We are confident that we could have captured more birds had we had additional personnel.
We continue to conduct ancillary studies as time allows at Barrow. Avian influenza studies were a prominent feature of our work in 2006 - all captured birds were swabbed to test for the highly pathogenic H5N1 avian influenza virus. Nathan Coutsoubos (University of Alaska, Fairbanks) completed the second year of his PhD studies investigating how the construction of a landfill and the experimental flooding/draining of a wetland influence shorebirds (see his report). We also placed radio transmitters on 18 individuals to help Audrey Taylor (PhD, University of Alaska Fairbanks) document movements to postbreeding sites (see her report). Finally, we collected eggs from Dunlin and Red Phalaropes for the second year in a row as part of a collaborative project with Sarah Jamieson (PhD, Simon Fraser University) to investigate whether shorebirds use endogenous or exogenous resources to produce eggs.
Three other studies were also occurring at this location. Their summaries follow:
(1) Behavioral Ecology of Pectoral Sandpipers
Investigators: Bart Kempenaers and Mihai Valcu, Max Planck Institute for Ornithology, and Richard Lanctot, U.S. Fish and Wildlife Service
In 2006 we continued our field study on the pectoral sandpipers in the same area as in 2005 (71.32 N, 156.66 W), but enlarged by 0.6 km2 to a total surface of 2.6 km2. We captured (using mistnets or nest-traps) 298 adult individuals (176 males and 119 females). Five males and one female were recaptures from 2005. Besides the standard morphometric measures, we also measured the thickness of the male throat sack using a modified skinfold calliper. All individuals were blood sampled and marked with a unique combination of colour bands. The colour bands allowed us to re-sight each individual present on the study area on a daily basis. For each re-sighting, the individual's GPS position and a few standardised behavioural measures were recorded. We found a total of 87 nests, most of them in the early incubation stage. Based on our previous successful experience, we collected all eggs and artificially incubated them. The overall hatching success (at least one hatched young per nest) was 85%, which is only 5 % lower than the natural hatching rate of this species recorded on an adjacent plot. However, our method reduced predation of clutches to zero, so that overall more offspring were born in the study area. Within a few hours after hatching each chick was measured and weighed and a small blood sample was collected. All hatched chicks were brought back to the incubating female and in all cases they were accepted immediately.
(2) Pre-migratory movements and physiology of shorebirds staging on Alaska's North Slope
Investigators: Audrey Taylor and Abby Powell, University of Alaska Fairbanks, and Richard Lanctot, U.S. Fish and Wildlife Service
Little information exists to quantify pre-migratory shorebird distribution across Alaska's North Slope or what factors may influence site selection, movement patterns, or residency times. This information is critical given increased levels of human activity and development near littoral areas across the Arctic Coast. This project was initiated to gain a better understanding of the abundance, distribution, phenology, movements, and physiology of post-breeding shorebirds during the staging period, and to aid in assessing how future industrial and human activity across the North Slope may affect shorebird populations. The specific objectives for this research are (1) to assess the abundance, distribution, and species composition of shorebirds staging along North Slope coastlines prior to the fall migration, (2) to quantify phenological aspects of staging, such as timing of arrival after breeding for adult and hatch-year birds, overall and species-specific peaks in shorebird numbers, residency times at staging sites, and movement patterns of birds across the North Slope, and (3) to examine differences in measures of physiological condition (fattening rates and stress hormone concentrations) among species and sites.
In 2006, we conducted four fixed-wing aerial surveys designed to count staging shorebirds along the entire North Slope coastline from the southern end of Kasegaluk Lagoon (69.28490øN, 163.27091øW) to the eastern border of the Arctic National Wildlife Refuge (69.66046øN, 141.06690øW). Survey dates were (1) 22-26 July, (2) 3-7 August, (3) 9-17 August, and (4) 23-27 August 2006. Over 30,000 individual shorebirds were counted during the four surveys; the majority of these were small calidrid sandpipers and phalaropes. We also continued our site-specific studies examining staging phenology and physiology at five locations across the North Slope (Barrow, Peard Bay, Colville River delta, Sagavanirktok River delta, and Okpilak River delta), and added an additional camp at Icy Cape in Kasegaluk Lagoon. Personnel at each location conducted regular surveys to examine shorebird abundance, distribution, species composition, and habitat use from mid July to early August. Field camp crews also captured birds to collect blood samples for analysis of fattening rates and stress hormone levels, and to band and radio-equip individuals to determine length of stay (LOS) at each site. In total, we banded 698 shorebirds of five species across the North Slope (dunlin, western sandpipers, semipalmated sandpipers, red phalaropes, and red-necked phalaropes), collected close to 600 blood samples, and radio-equipped 88 adults and 112 hatch-year birds of the same five species. Each camp maintained an automated telemetry station and conducted manual telemetry on a regular basis to examine the probability of birds dispersing between and among breeding and staging areas. Two additional remote telemetry stations were located on the Canning River delta and at a site 40km south along river to detect shorebirds (particularly semipalmated sandpipers) potentially using the river as a migration corridor. We also conducted telemetry surveys from the airplane while doing abundance surveys as described above.
Several locations that appeared to be hotspots of shorebird abundance in 2005 also hosted large numbers of staging shorebirds in 2006: Peard Bay, the southeast shoreline of Elson Lagoon, and the east side of Dease Inlet. In addition, phalaropes of both species appeared to use the barrier islands in the Beaufort Sea extensively. Semipalmated sandpipers were the most common species at all field camps again; individuals of this species also exhibited the highest fattening rates and departed from the North Slope earlier than the other species studied. Radio-equipped semipalmated sandpipers tended to move north along the Chukchi coast and east along the Beaufort coast after departing from their banding location. This is similar to the pattern observed in 2005 and leads us to believe that birds may use multiple sites along the North Slope as staging sites, or at least as temporary resting/refueling stopovers. Dunlin appeared at coastal staging areas in mid to late August, and exhibited lower rates of fat deposition and longer LOS at individual sites than other terrestrially-feeding species. We are currently investigating whether dunlin molting concurrent with pre-migratory fattening affects their rate of fat deposition, and is regulated by stress hormone (corticosterone) levels. Data entry and analysis is ongoing and is expected to comprise the majority of the upcoming year.
(3) Task: Tundra-Nesting Shorebirds in Relation to Landscape Transformation and Climate Change
Investigators: Nathan Coutsoubos and Falk Huettmann, University of Alaska Fairbanks, and Richard Lanctot, U.S. Fish and Wildlife Service
In June and July 2006, we carried out the second year of a dissertation research program on tundra-nesting shorebirds in relation to ongoing local-scale landscape transformation and climate change. Work was conducted 5-12 km south of Barrow and involved studies at a recently constructed landfill and at a water-level manipulated wetland.
The North Slope Borough began constructing a new, modern landfill during the winter of 2004/2005. Construction will be completed this winter and waste transfer will start in late 2006. This construction project provides an ideal opportunity to determine how local birds respond to a landfill prior to and during landfill use. Ten transects (8.5 km total) were established near the landfill (stratified by distance and direction). Distance sampling surveys were conducted along these transects weekly during the territory establishment, nest initiation and incubation periods of the breeding cycle, for a total of 5 surveys per transect. Individual avian detections (single or clusters) numbered 1890 from 28 species, including 1133 shorebird detections of nine species. The most common shorebirds (unadjusted counts) were Pectoral Sandpiper (n=475 detections), Red Phalarope (n=333), and Dunlin (n=160). This and similar information collected in succeeding years will allow us to assess changes in shorebird distribution and abundance as the landfill grows. We also measured parental attendance at 12 shorebird nests located in and near the landfill, using within-nest temperature probes. This information may provide mechanistic evidence of how landfill disturbance affects nesting shorebirds.
Additionally, we carried out surveys in a 60-ha wetland, whose water levels will be manipulated over the next several years, to mimic the predicted effects of global climate change on tundra hydrology (the Barrow Biocomplexity Project). This year, no wetland manipulation occurred. Surveys were conducted twice weekly on three separate 300m transects during shorebird nesting. A total of 392 avian detections were recorded belonging to 24 species, including 291 shorebird detections of 7 species. The most common shorebirds (unadjusted counts) were Red Phalarope (n=94 detections), Pectoral Sandpiper (n=56), and Long-billed Dowitcher (n=38). Shorebird surveys will continue as the local hydrology is manipulated, providing experimental evidence of the local effects of a warming climate and altered hydrology on shorebirds.
Recent Publications:
Liebezeit, J.R., P.A. Smith, R.B. Lanctot, C. Gratto-Trevor, H. Schekkerman, D. Tracy, J.A. R. Robinson, H. Meltofte, S. Kendall, R.J. Rodrigues, J.A. Morse, and B.J. McCaffery. 2007 Determining incubation stage of shorebird eggs using the flotation method: species-specific and generalized regression models. Condor 109:32-47.
Johnson, J., R.B. Lanctot, B. Andres, J. Bart, S. Brown, S. Kendall, and D. Payer. (in press.) Distribution of shorebirds breeding on the Arctic Coastal Plain of Alaska. Arctic.
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