Caribou (Rangifer tarandus granti) use lichens, when available, as primary forage on their winter range. In boreal forest habitats, wildland fires effectively destroy lichens, and overwintering caribou are known to avoid burned areas for decades while lichen communities regenerate. However, little has been published about caribou response to burned habitat in tundra ecosystems. To assess the relationship between winter caribou distribution and burned areas, we instrumented Western Arctic Herd caribou with satellite telemetry collars and evaluated their locations in relation to recent burns of known age (≤ 55 years old) across northwestern Alaska. We analyzed caribou distribution for different habitat types (tundra and boreal forest), age categories of burns, and possible edge effects. We also reanalyzed the data, limiting available habitat to a uniform traveling distance (5658 m) from daily satellite locations. Using selection indices that compared caribou use of burns and buffers to their availability, we found that caribou strongly selected against burned areas within the tundra ecosystem. Recent burns were selected against at both large (range-wide) and intermediate (5658 m) spatial scales. Caribou particularly selected against 26-to 55-year-old burns and the interior (core) portions of all burns. We found that caribou were more likely to select burned areas in the late fall and early spring than midwinter. Increased fires in northwestern Alaska could decrease the availability and quality of winter habitat available to the herd over the short term (up to 55 years), potentially influencing herd population dynamics and reducing sustainable harvest levels. We recommend that fire managers consider caribou midwinter range condition and extent: however, management that achieves a mosaic pattern of fire history may benefit a wide array of species, including caribou. A better understanding of the current regional fire regime and the distribution of available winter range will be required before practicable management recommendations can be developed for this herd.

The purpose of this work is to determine interannual variability in abundance, occupancy, distribution, and nesting success of Gyrfalcons (Falco rusticolus) and other cliff-nesting raptors within 14,150 km 2 of the Seward Peninsula in western Alaska. From 2005 through 2010, comprehensive helicopter surveys were used for annual inspections of 679 discrete rock cliffs typically occupied by raptors within the study area. Based on 1,372 cumulative nesting events at 454 unique locations, Gyrfalcons comprised 18% of total raptor occupancy, ranging from 40-43 locations annually. Individual Gyrfalcon observations (n = 250) show use of 154 separate cliff locations by single birds (16%; n=39), unsuccessful pairs (11%; n=28), and successful pairs (73%; n=183). Nest types and usage included: cliff stick nests constructed by other raptors and ravens, 73%; rock ledges, 16%; man-made structures, 7%; and tree stick nests, 2%. Mean nearest neighbor distances varied from 8.8 to 10.0 km with distances ranging from 0.8 to 37.6 km indicating that both clustered and dispersed nesting are characteristics of this area, each strongly influenced by local topography, dissected rock cliffs and broad lowland areas with no cliffs. Clustering of closely spaced alternate nesting locations yields 96 unique nesting areas with minimal interannual overlap and maximum distance separation among occupied sites, suggesting that pairs have relatively high rates of movement to 'new' nesting areas in successive years. Based on iterative counts of pair occupancy at the same location (n=248 nesting events), the majority were occupied 1 year (n=79 nesting events) before becoming vacant. Longer periods of pair occupancy were observed at 30 locations with 2-year tenure (n=60), 14 locations with 3-year (n=42), 8 locations with 4-year (n=32), 4 locations with 5-year (n=20) and 3 locations with 6-year occupancy (n=18). Since abundance of pairs is stable through time, the high frequency of 1-year nesting events suggests variable site selection and low nest site tenacity among pairs. Gyrfalcon occupancy ranged from 31-39 pairs, yielding a maximum nesting density of 2.7 pairs per 1,000 km 2. Successful pairs varied annually from 72-93% of total occupied locations; brood size (n=183 locations with nestlings) ranged from 2.35-2.70 young/successful pair (1.50-2.23 young/total pair). Hatch dates ranged from 7 May to 27 June with low intra-or interannual nesting synchrony and little evidence of recycling due to nesting failure. Brood size rates are probably minimum values due to errors associated with finding or counting nestlings from an aerial survey platform. Even if brood rates assessed in June decline as fledging approaches, the observed values remain high enough to explain the stability of numbers and pairs in the Seward Peninsula population.

The peregrine falcon (Falco peregrinus) and the gyrfalcon (Falco rusticolus) are top avian predators of Arctic ecosystems. Although existing monitoring efforts are well established for both species, collaboration of activities among Arctic scientists actively involved in research of large falcons in the Nearctic and Palearctic has been poorly coordinated. Here we provide the first overview of Arctic falcon monitoring sites, present trends for long-term occupancy and productivity, and summarize information describing abundance, distribution, phenology, and health of the two species. We summarize data for 24 falcon monitoring sites across the Arctic, and identify gaps in coverage for eastern Russia, the Arctic Archipelago of Canada, and East Greenland. Our results indicate that peregrine falcon and gyrfalcon populations are generally stable, and assuming that these patterns hold beyond the temporal and spatial extents of the monitoring sites, it is reasonable to suggest that breeding populations at broader scales are similarly stable. We have highlighted several challenges that preclude direct comparisons of Focal Ecosystem Components (FEC) attributes among monitoring sites, and we acknowledge that methodological problems cannot be corrected retrospectively, but could be accounted for in future monitoring. Despite these drawbacks, ample opportunity exists to establish a coordinated monitoring program for Arctic-nesting raptor species that supports CBMP goals.

We know little regarding how specific aspects of habitat influence spatial variation in site occupancy by Arctic wildlife, yet this information is fundamental to effective conservation. To address this information gap, we assessed occupancy of 84 Gyrfalcon (Falco rusticolus Linnaeus, 1758) breeding territories observed annually between 2004 and 2013 in western Alaska. In line with the theory of population regulation by site dependence, we asked whether Gyrfalcons exhibited a nonrandom pattern of site selection and if heterogeneous landscape attributes correlated with observed occupancy patterns. We characterized high- and low-occupancy breeding territories as those occupied more or less often than expected by chance, and we evaluated land cover at 1 and 15 km circles centered around nesting territories to identify habitat variables associated with observed occupancy patterns. We tested 15 competing models to rank hypotheses reflecting prey and habitat variables important to nesting Gyrfalcons. We confirmed a nonrandom pattern of site selection but found only weak evidence that the distribution of prey habitat was responsible for this pattern. We reason that preferential habitat use by nesting Gyrfalcons may be determined by spatial scales other than those we measured or may be driven by landscape-level attributes at time periods other than during the brood rearing period.

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