Revised distribution of an Alaskan endemic, the Alaska Hare (Lepus othus), with implications for taxonomy, biogeography, and climate change

Michelle M. Cason, Andrew P. Baltensperger, Travis L. Booms, John J. Burns, Link E. Olson

Department of Mammalogy, University of Alaska Museum, 907 Yukon Drive, Fairbanks, AK 99775, USA; Department of Biology and Wildlife, University of Alaska Fairbanks, 982 N. Koyukuk Drive, Fairbanks, AK 99775, USA

Gates of the Arctic National Park, National Park Service, 4175 Geist Road, Fairbanks, AK 99709, USA

Alaska Department of Fish and Game, Wildlife Diversity Program, 1300 Cllege Road, Fairbanks, AK 99701, USA

Department of Mammalogy, University of Alaska Museum, 907 Yukon Drive, Fairbanks, AK 99775, USA

Correspondence: Michelle Cason (email: Michelle Cason (email: mmcason@alaska. edu ). This article is open access. This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/deed.en_GB.

Received May 08, 2015. Accepted March 08, 2016.

Arctic Science, 2016, 2(2): 50-66, https://doi.org/10.1139/as-2015-0019

In this paper Top of page Introduction Materials and methods Results Discussion Taxonomy and gene flow References Appendix Abstract The Alaska Hare (Lepus othus Merriam 1900) is the largest lagomorph in North America but remains one of the most poorly studied terrestrial mammals on the continent. Its current distribution is restricted to western Alaska south of the Brooks Range, but historical accounts from north of the Brooks Range (the North Slope) have led to confusion over its past, present, and predicted future distributions. To determine if L. othus occurs or historically occurred on the North Slope, we surveyed museum collections, vetted observational accounts, and produced a spatial distribution model based on the resulting georeferenced records. We located a historic specimen long presumed lost that suggests the occurrence of L. othus on the North Slope as recently as the late 1800s. We also uncovered evidence of L. othus and (or) Mountain Hare (Lepus timidus Linnaeus 1758) on several islands in the Bering Sea, raising the possibility of recurring gene flow between these closely related species across seasonal ice connecting Asia and North America. While our results paint a more complete picture of the current distribution of L. othus, persistent uncertainties surrounding its taxonomic status and potential northward range shift onto lands reserved for oil and gas development call for additional study. Key words: Alaska Hare, Arctic Hare, Lepus othus, Mountain Hare, North Slope

In this paper Top of page Introduction Materials and methods Results « Discussion Taxonomy and gene flow References Appendix Results We located 318 specimens of L. othus from 12 museum and other collections and were able to georeference 305 from their locality descriptions (Fig. 3; Table S1). Many were already associated with geographic coordinates available from the host museum. These localities spanned much of Alaska’s west coast but the majority (175) of specimens were collected from the Seward Peninsula (Fig. 3). The current northernmost range limit was extended approximately 50 km north after collection of the first L. othus voucher (UAM 120460) from Noatak National Preserve in April 2014. There was also a credible sighting (UAMObs 213) of an L. othus individual in 1978 in the western Brooks Range approximately 150 km northeast of where UAM 120460 was collected. The southernmost specimens were collected in Cold Bay, approximately 50 km from the terminus of the Alaska Peninsula, as recently as 1993 (UAM 42143). We personally confirmed the species identification of the northern- and southernmost specimens, both of which are housed at UAM. Most specimens were collected close to Alaska’s western coastline. The inland-most specimens were collected near St. Mary’s, less than 150 km from the coast. Several reliable observations (UAMObs 219-225) originated near Iliamna Lake, which is farther east than almost all specimen collection localities but less than 100 km inland from the Gulf of Alaska. We located the “lost” McIlhenny specimen (CMN 31930), a skull and postcranial skeleton collected from near Barrow, in the Mammal Collection at the Canadian Museum of Nature. Data on the specimen tag confirm that it is the same specimen listed in the expedition’s report (Stone 1900). We borrowed the specimen and verified that the craniodental measurements were within the range of the L. othus specimens measured by Anderson (1974) and exceeded the maximum basilar skull length of L. americanus (67 mm) reported by Hall (1981). Visual comparisons also confirmed that it is not L. americanus. Two new credible observations of L. othus on Unimak Island (the easternmost of the Aleutian Islands) in 2013 and 2014 (UAMObs 182, UAMObs 192) were reported, and a photograph of an L. othus individual on Hagemeister Island (UAMObs 181) was taken by a camera trap at a walrus haulout site in 2013. Both Hagemeister and Unimak are close to mainland Alaska (<5 and <1 km, respectively) and are sometimes connected to the mainland by sea ice in late winter and early spring. Additionally, one or more very large hares fitting the description of either L. timidus or L. othus were reported from St. Lawrence Island (Fig. 3) in the winter of 2012 (G. Sheffield, personal communication) and are the first known sighting of a hare on that island. Prior to this study, Alaska Hares were not known from any of these islands. Russia’s Chukotsk Peninsula and Alaska’s Seward Peninsula are 80 km apart. Midway between them lie the two Diomede Islands. Large-bodied hares currently identified as L. othus have been collected from Little Diomede Island in 1936 (USNM 260900) and more recently in 2014 (UAM 120797, UAM 122839) but have only been sporadically reported from the island. During winter 2013–2014, several hares were observed on Little Diomede (including the two UAM specimens). UAM 120797 was pregnant with seven near-term embryos when shot by subsistence hunters in June 2014. Little Diomede lies 37 km west of Alaska’s Seward Peninsula and less than 4 km east of Russia’s Big Diomede Island, which in turn is only 35 km east of the Chukotsk Peninsula; all are interconnected by sea ice for up to 6 months out of the year (NSIDC 2013). In the 1960s, bush plane pilot Bill Munz reportedly saw a “huge” aggregation of large-bodied hares moving east on the sea ice between Little Diomede Island and Cape Prince of Wales (J. Jacobson, personal communication) (Fig. 3), which is on the western tip of the Seward Peninsula. Whether the hares collected from Little Diomede in 2014 represent L. othus from Alaska or L. timidus from Russia remains unclear, as does the present occurrence of hares on Big Diomede. However, residents on Little Diomede recounted the regular occurrence of hares on Big Diomede and sporadic dispersal to Little Diomede (personal communication to J.J.B.) in the 1960s. Curiously, no specimens or observations of hares are known from Nunivak Island (Fig. 3), the second-largest island in the Bering Sea and only 30 km from mainland western Alaska, to which it is seasonally connected by sea ice. Residents and hunting guides on Nunivak report that hares do not occur on the island (W. Don, personal communication). Our spatial distribution model (Fig. 4) predicts their likely presence on Nunivak, but the reason(s) for the apparent absence of L. othus there remains unknown.

»View larger version Fig. 4. Spatial distribution model of the present distribution of Lepus othus. Red circles mark presences (georeferenced collection localities). Blue circles indicate pseudoabsences. Relative indices of occurrence (RIO) values greater than 0.55 indicate regions of likely presence, and values less than 0.55 indicate regions of likely absence. Murie (1959) noted the absence of L. othus on Unimak Island (Fig. 3) after his faunal survey of the Alaska Peninsula and Aleutian Islands in the 1930s. MacDonald and Cook (2009) reported no island records from southwest Alaska, aside from a failed introduction on Chirikof Island (Fig. 3). However, one specimen (USNM 203278; identification confirmed by L.E.O.) is listed as having been collected from Sand Point (Fig. 3), on Popov Island, in 1913. Popov Island is not surrounded by sea ice in the winter, and ocean currents in the Unga Strait separating the island from the southern coast of the Alaska Peninsula are strong and constant. The village of Sand Point was, like Barrow, a trading center for many years; it is possible that the specimen may have been collected on the mainland and brought to Sand Point. Alaska Hares are not known to occur on Popov Island today, and Snowshoe Hares introduced to the island in 1955 are reported to be abundant (MacDonald and Cook 2009; D. Watts, personal communication). The two observations of L. othus on Unimak (UAMObs 182 and UAMObs 192) and a photograph of L. othus on Hagemeister (UAMObs 181) are additional evidence of L. othus on islands in southwestern Alaska. The spatial distribution model closely matched the known distribution based on specimen and observation localities (Fig. 4). The ROC value was 0.98, the balanced error rate was 0.06, the sensitivity was 94.24%, and the specificity was 94.00%. Distance to March sea ice and the distance to the coastline were the most important variables in the model (Table 1). The northernmost specimen collection locality is in an area of likely L. othus presence, as predicted by the spatial distribution model. However, the location of the northernmost credible observation is in the midst of the Brooks Range, where the model predicts the absence of L. othus. The model did predict the presence of L. othus on St. Lawrence Island, despite the pseudo-absence localities used in the data set. We did not include the observation of a large-bodied hare on St. Lawrence Island as a presence point because we received it third-hand and it is not considered a catalogued observation.

Acknowledgements This project was funded by a grant from the Alaska Department of Fish and Game (through United States Fish and Wildlife Service Division of Federal Assistance State Wildlife Grant T-1-6), with additional funding from the University of Alaska Fairbanks Graduate School, the Arctic Institute of North America, the David Burnett Dunn Memorial Award, and the University of Alaska Museum. We are deeply grateful to the following individuals, management agencies, and museums for their field support, specimen observations, specimen loans, and access to collections: C.P. Barger (Alaska Department of Fish and Game), S. Lowe (US Fish and Wildlife Service), J. Lawler (National Park Service), A. Whiting (Native Village of Kotzebue), N.A. Boase and K. Khidas (Canadian Museum of Nature), M. Flannery and J.P. Dumbacher (California Academy of Sciences), J. R. Demboski (Denver Museum of Science and Nature), J. Chupasko and H. Hoekstra (Museum of Vertebrate Zoology, Harvard University), J.L. Dunnum and J.A. Cook (Museum of Southwestern Biology, University of New Mexico), M. Revelez and J.K. Braun (Sam Noble Museum of Natural History, University of Oklahoma), G. Shugart (James R. Slater Museum of Natural History, University of Puget Sound), C.W. Thompson and P. Myers (University of Michigan Museum of Zoology), S. Peurach, N. Woodman, and A.L. Gardner (National Museum of Natural History, Smithsonian Institution), J.E. Bradley and S.E. Santana (Burke Museum, University of Washington), G. Sheffield (Marine Advisory Program, University of Alaska Fairbanks), and I. Ahkvaluk. For advice, assistance, and invaluable discussion, we thank A.M. Gunderson, K.B.P. Hildebrandt, K.M. Everson, J.A. Nations, D.R. Klein, D.E. Watts, D. Tinker, E. Waltari, and B.J. McDaniel. Finally, we thank the more than 70 field biologists, subsistence hunters, trappers, and other collectors not mentioned above — living and deceased — whose efforts to collect and archive voucher specimens made this study possible.

In this paper Top of page Introduction Materials and methods Results Discussion Taxonomy and gene flow References Appendix

References