Mammal Inventory Report Crook Point, Oregon, 2009. Siskiyou Research Group

Introduction and Study Area The Crook Point Unit of Oregon Islands National Wildlife Refuge is a 134-acre undeveloped coastal headland located approximately 12 miles south of Gold Beach, Oregon. Notwithstanding post-European settlement activities of livestock grazing and timber harvesting, Crook Point provides exceptional examples of coastal headland habitats, which have largely disappeared from Oregon as a result of development and conversion (Kagan 2002). Currently, Crook Point provides habitat for rare plant species such as Poa unilateralis, Lasthenia ornduffii, and Artemisia pycnocephala (Kagan 2002, Chan 2001, Bilderback 2008). Moreover, the associated offshore islands and rocks provide important nesting habitat for seabirds, haul-out and breeding areas for marine mammals, and suitable cliff habitat for nesting peregrine falcons (Ledig 2009). Saddle Rock, the largest island associated with Crook Point, provides nesting habitat for a large population of Leach’s storm petrels (PRBO 2004). There is evidence the Saddle Rock population is being decimated by mammalian predators (reference).

In 2000 U.S. Fish and Wildlife Service (USFWS) acquired this coastal headland making it the second mainland unit in the Oregon Islands National Wildlife Refuge system. Presently USFWS is focusing on site restoration, resource protection, and biological inventory, monitoring, and research. This mammal survey is part of an effort to document the biological diversity of Crook Point. Prior to this survey no systematic mammal inventory work has been conducted at Crook Point.

Objectives The primary objective of this survey was to compile a mammalian species list for Crook Point using multiple detection methods of trapping, motion-triggered trail cameras, direct observation, and animal sign (prints, scat, excavations). Secondary objectives sought to compare mammalian diversity and abundance between the largest vegetation types, and to collect tissue samples for genetic analysis to determine if genetic differences exist between Microtus populations on Saddle Rock and mainland Crook Point.

Products A database (Microsoft Access®) containing polygon information, captured species information, and spreadsheets of data tabulations will be provided in conjunction with this report. Other products generated by this survey included a small number of study skins and skulls from collected mammals, microtine tissue samples, and an electronic file of digital photographs of animals taken by the trail cameras. Mark P. Miller of the USGS Forest and Rangeland Ecosystem Science Center in Corvallis, Oregon conducted genetic analyses of microtine tissue samples. Preliminary results from this work are available and a final report is expected in May 2010.

Methods Vegetation associations identified, described, and mapped by Kagan (2002) were used to stratify the study area into sampled polygons for measuring mammalian diversity (Figure 1). In addition to the 18 vegetation types described by Kagan (2002), I added 3 plots identified as Saddle Rock, Beach (wrack line), and Road for a total of 21 vegetation units (Table 1). Of the 21 vegetation units, 8 were not sampled due to accessibility (e.g. steep

1 Mammal Inventory Report Crook Point, Oregon, 2009. Siskiyou Research Group

bluffs, cliffs, or impenetrable vegetation) or because of small size. I assumed that mammals utilizing these areas would be represented through survey efforts occurring in adjacent vegetation plots.

Figure 1. Infrared aerial photograph of Crook Point showing refuge property boundaries, vegetation units, and approximate locations of selected transects and trap centers.

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I reviewed animal-habitat associations and species range maps (Verts and Carraway, 1998) to determine mammal species most likely to occur at Crook Point (Table 2) and the best sampling methods for detecting these species (Quayle 1998, Gomez, 2008). I conducted trapping fieldwork in two sessions, May 20, - May 25, 2009 and June 19, - June 25, 2009 when mammal activity is high (Verts and Carraway, 1998) and there is a low probability of rainfall - and consequently a lower probability of weather related trap mortalities. Trail camera survey work began in November 2009 and concluded in February 2010. I operated the trail cameras in winter when naturally occurring food sources are presumably less abundant and carnivores might be more attracted to the meat- baited stations.

With exception, the basic trapping configuration used in each sampled vegetation unit consisted of a transect line of 10 Sherman live traps (3”X3”X9”), 2 Tomahawk live traps (model 201), and an array of 4 pitfall traps. Typically, a trap center was identified in each vegetation unit where a pitfall array was constructed. Pitfall traps were assembled from stacking and duct-taping two 64-ounce tin cans together. The bottom was removed from the top can to create a 16-inch deep metal tube that was placed into a hole created by a posthole digger. The lip of the top can was placed flush with the ground. In most sampled vegetation units a pitfall array consisted of 4 pitfall traps arranged in a 2- dimensional tetrahedron (Figure 1). The outer pitfalls were placed approximately 3 meters from the central pitfall and between the central pitfall trap and the outer pitfalls an artificial drift fence of 3.5-inch high plastic garden border material was staked in place. The purpose of this drift fence was to direct small animals toward a pitfall. Nesting material of grass was placed in each pitfall for cover and thermal protection for caught animals. Also, mealworms were placed in pitfalls to reduce shrew mortality from starvation.

Two Tomahawk traps were placed within 10 meters of this pitfall array. In forested polygons one Tomahawk trap was placed on the ground and one Tomahawk trap was attached to the bole of a tree (with aluminum nails) approximately 1.5 meters from the ground. In non-forested polygons both Tomahawk traps were placed on the ground.

Transect lines consisted of 10 Sherman traps placed at 15-meter intervals. Transect lines were established near trap center and individual Sherman traps were subjectively placed on or near the transect line to take advantage of natural drift fences such as downed trees, rocks, and topography, which also offered cover from sun, wind, and moisture. Cedar shingles were placed on top of both Sherman and Tomahawk traps to provide additional protection from weather.

To compare mammalian diversity and abundance between the 4 largest vegetation units (Sitka Spruce/Salal Forest (2), Sitka Spruce/Red Alder/Thimbleberry Riparian (6), South Coast Headland Prairie (8), and Open South Coast Headland Erosion Forblands and Dunes (10)), 3 basic trapping configurations were established in each vegetation unit (polygon) for a total of 48 traps/polygon (30 Shermans/12 pitfalls/6 Tomahawks). The typical pitfall configuration was changed from the 2-dimensional tetrahedron shape to a linear shape in polygon 6 to better conform to the linear nature of the inner riparian

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habitat. Trapping was conducted for 5 trap-nights (Wilson 1996, Quayle 1998, Gomez 2008).

Figure 2. Basic Trapping Configuration, Crook Point, Oregon

Pitfalls built from 2 stacked tin cans.

Drift fence

2 Tomahawks placed within Pitfalls 10 m of trap separated by center 3m and 120o

Transect line: 10 Sherman traps spaced every 15m.

One basic trapping configuration was placed in each of the smaller vegetation polygons (Disturbed Area (1), Old Pasture (4), Sitka Spruce Regenerating Forest (5), Headland Riparian Shrublands (14), and Red Alder/Salmonberry Riparian Forest (19)) for a total of 16 traps/polygon (10 shermans/4 pitfalls/2 Tomahawks). For the remaining 3 sampled polygons (Saddle Rock (20), Road (23), and Beach (22)), a modified trapping configuration was used. On Saddle Rock one transect line of 20 Sherman live traps was established. Tomahawk traps and pitfall traps were not used on Saddle Rock in order to minimize disturbance to nesting Leach’s storm petrels. The Beach wrack line (polygon 22) consisted of one transect of 15 Sherman live traps, 2 Tomahawk traps, and a linear array of 4 pitfall traps. The Road plot (polygon 23) was identified as unique even through it traverses several vegetation units already described. Ten Tomahawk traps were deployed along this linear plot. Additionally, two large (coyote-sized) live traps were deployed for 5 days along the Beach transect (polygon 22) and the Headland Riparian Shrubland transect (polygon 14). These traps were camouflaged in vegetation (polygon 14) and driftwood (polygon 22).

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All Sherman and Tomahawk traps were baited with a mixture of rolled oats, peanut butter, and molasses, except for 4 of the Tomahawk traps located along the Road plot (polygon 23), which were baited with alfalfa pellets to target Sylvilagus. The extra large Tomahawk traps were baited with canned dog food/dry cat food/peanut butter bait mixture. Traps were checked daily.

Specimens were collected for difficult-to-identify insectivores and microtines and study skins and skulls were prepared to validate field identifications. Project-related animal mortalities provided some specimens. Collection of insectivores, microtines, and geomyids were identified to species using range and habitat information and morphological, dentition, and skull characteristics (Verts and Carraway 1998, Jameson and Peeters 2004, Maser and Storm 1970).

The locations of transect-arrays were identified by vegetation polygon and GPS-derived latitude-longitude coordinates (when satellite coverage was available) and entered into the database. Capture data included transect line or trapping array identifier, date, species, and comments. Species information recorded in the field and entered into the database included gender, age (adult/juvenile), reproductive condition (lactating/non- lactating), and new capture/recapture information.

Tissue samples were collected from all captured adult voles trapped on Saddle Rock and mainland Crook Point for genetic analysis conducted by USGS Forest and Rangeland Ecosystem and Science Center in Corvallis, Oregon. Tissue samples from microtines were collected by snipping a small piece of the outer ear with sharp scissors and storing the tissue in vials containing a buffer solution of 70% isopropyl alcohol.

Animals not collected and not ear-clipped were marked by fur clipping on the dorsum (Anderson 2006) to identify them as previously captured for the purpose of collecting relative abundance data.

Beginning in November 2009 through February 2010 remote motion-triggered cameras were operated in polygon 6 and polygon 2. ‘No Flash’ Cuddeback® digital infrared trail cameras were used with 2-GB compact flash cards. Camera stations were baited with store-bought chickens and the camera stations were checked every seven to ten days to re-bait, collect and change compact flash cards, and check/replace batteries.

5 Mammal Inventory Report Crook Point, Oregon, 2009. Siskiyou Research Group

Table 1. Vegetation Units / Plant Associations / Trapping Polygons at Crook Point NO CODE PLANT ASSOC SAMPLED 1 DA Disturbed Areas 4 PF, 2 TMH, 10 SH 2 PISI/GASH Sitka Spruce/Salal Forest 12 PF, 6 TMH, 30 SH, 1 TC 3 RUSP/RUPA Salmonberry/Thimbleberry Not Sampled shrubland 4 OP Old Pasture 4 PF, 2 TMH, 10 SH 5 PISI Sitka Spruce Regenerating 4 PF, 2 TMH, 10 SH Forest 6 PISI/ALRU/RUPA Sitka Spruce/Red Alder/ 12 PF, 6 TMH, 30 SH, 1 TC Thimbleberry Riparian 7 PISU/RUSP Sitka Spruce/Salmonberry Not Sampled Forest 8 SCHP South Coast Headland 12 PF, 6 TMH, 30 SH Prairie 9 PICO/PISI Lodgepole pine/Sitka Spruce Not Sampled evergreen shrub 10 OSCHD Open South Coast Headland 12 PF, 6 TMH, 30 SH Erosion Forblands and Dunes 11 SCEB Steep, Coastal, Erosion Bluffs Not Sampled 12 SCHG South Coast Headland Not Sampled Grassland 13 SRC Steep, Rocky Cliffs Not Sampled 14 HRS Headland Riparian Shrubland 4 PF, 2 TMH, 10 SH 15 BGD Beachgrass Dunes Not Sampled 16 RMCR River Mouth Coastal Riparian 4 PF, 2 TMH, 10 SH 17 Number Skipped 18 PISI/POMU Sitka Spruce/Swordfern Not Sampled Forest 19 ALRU/RUSP Red Alder/Salmonberry 4 PF, 2 TMH, 10 SH Riparian Forest 20 SDLRK Saddle Rock - Coastal Headland 20 SH Grassland 22 BCH Beach (Wrack Line) 4 PF, 3 TMH, 15 SH 23 RD Road 10 TMH

PF = Pitfall, TMH = Tomahawk, SH = Sherman, TC = Trail Camera

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Table 2. Mammals Likely to Occur at Crook Point (Verts and Carraway 1998)

Species Family Order Common Name (Subfamily) Didelphis virginiana Didelphidae Didelphimorphia Opossum Sorex bendirii Soricidae Insectivora Pacific Water Shrew Sorex pacificus Pacific Shrew Sorex sonomae Fog Shrew Sorex trowbridgii Trowbridge's Shrew Sorex vagrans Vagrant Shrew Neurotrichus gibbsii Talpidae Insectivora Shrew-mole Scapanus latimanus Broad-footed Mole Scapanus orarius Coast Mole Scapanus townsendii Townsend's Mole Sylvilagus bachmani Leporidae Lagomorpha Brush rabbit Lepus californicus Black-tailed Jackrabbit Aplodontia rufa Aplodontidae Rodentia Mountain Beaver Tamias siskiyou Sciuridae Rodentia Siskiyou Chipmunk Tamias townsendii Townsend's Chipmunk Spermophilus beecheyi California Ground Squirrel Sciurus griseus Western Gray Squirrel Tamiasciurus douglasii Douglas' Squirrel Glaucomys sabrinus Northern Flying Squirrel Thomomys bottae Geomyidae Rodentia Botta's Pocket Gopher Thomomys mazama Western Pocket Gopher Castor canadensis Castoridae Rodentia American Beaver Muridae Peromyscus maniculatus (Sigmodontinae) Rodentia Deer Mouse Neotoma cinerea Bushy-tailed Woodrat Neotoma fuscipes Dusky-footed Woodrat Rattus norvegicus (Murinae) Rodentia Norway Rat Rattus rattus Black Rat Mus musculus House Mouse Clethrionomys californicus (Arvicolinae) Rodentia Western Red-backed Vole Phenacomys albipes White-footed Vole Phenacomys longicaudus Red Tree Vole Microtus longicaudus Long-tailed Vole Microtus oregoni Creeping Vole Microtus townsendii Townsend's Vole Ondatra zibethicus Common Muskrat Zapus trinotatus Dipodidae Rodentia Pacific Jumping Mouse Canis latrans Canidae Carnivora Coyote Urocyon cinereoargenteus Common Gray Fox Ursus americanus Ursidae Carnivora Black Bear Procyon lotor Procyonidae Carnivora Raccoon Martes americana Mustelidae Carnivora American Marten Mustela erminea Ermine Mustela frenata Long-tailed Weasel Mustela vison Mink Lutra canadensis River Otter Spilogale gracilis Mephitidae Carnivora Western Spotted Skunk Mephitis mephitis Striped Skunk Puma concolor Felidae Carnivora Mountain Lion Lynx rufus Bobcat Odocoileus virginianus Cervidae Artiodactyla White-tailed Deer

7 Mammal Inventory Report Crook Point, Oregon, 2009. Siskiyou Research Group

Results Sixteen terrestrial mammal species from 5 orders and 12 families (and 2 subfamilies) were detected at Crook Point (Table 3). A net total of 1,305 traps-nights (1,529 trap- nights minus 224 sprung or damaged traps) yielded 8 mammal species. Five mammal species were detected by direct observation and/or by sign, and three mammal species were captured by digital trail cameras. The most commonly trapped and widespread species at Crook Point was Peromyscus maniculatus. A total of 237 P. maniculatus individuals were captured in every vegetation unit (polygon) except Saddle Rock (polygon 20). Of the 237 individuals 148 were recaptured. Next in abundance and distribution, but far fewer in numbers, were Microtus longicaudus. I captured 45 M. longicaudus individuals with the majority (33) captured on Saddle Rock. The only mammals captured on Saddle Rock were M. longicaudus. Only 12 M. longicaudus were captured in the mainland polygons. Of the 45 captured M. longicaudus, 6 were recaptured, and 6 live and 10 dead were collected. Other species captured include Sorex trowbridgii (6), Thomomys bottae (4), Sorex vagrans (3), Mustela erminea (2), Sylvilagus bachmani (1), and Clethrionomys californicus (1). Five species documented through direct observation or by sign include Ursus americanus, Odocoileus virginianus, Lutra canadensis, Tamiasciurus douglasii, and Castor canadensis. Three species captured by the digital trail cameras include Lynx rufus, Spilogale gracilis, Procyon lotor (Appendix B). Signs of other species observed but not confirmed included scat of Canis latrans, excavation mounds of Scapanus ssp, and burrow holes of Aplodontia rufa.

Species Detections Gender Detection Polygon # M F Und Method Detected Castor canadensis* 1 X S 14 Clethrionomys californicus 1 1 T(pf) 5 Lutra canadensis common** X DO, S 22 Lynx rufus 1 X TC 2 Microtus longicaudus 45 20 24 1 T(pf,sh) 1,2,4,8,10,14,20,22 Mustela erminea 2 1 1 T(sh) 6,14 Odocoileus virginianus common X DO, S All except #20 Peromyscus maniculatus 237 105 113 19 T(pf,sh) All except #20 Procyon lotor common X S, TC 22, 6 Sorex trowbridgii 6 5 1 T(pf) 1,2,6 Sorex vagrans 3 2 1 T(pf) 1,2,6 Spilogale gracilis 1 X TC 6 Sylvilagus bachmani 2 2 T(tom), DO 4,23 Tamiasciurus douglasii common X DO 2,5 Thomomys bottae 4 1 2 1 T(pf), DO, S 1,8,10,22 Ursus americanus several X DO, S 1,2,6,19 Table 3. Summary of Mammal Detections. Crook Point, Oregon.

Detection Method: T = Trap (sh=sherman, pf=pitfall, tom=tomahawk) DO = Direct Observation, S = Sign, TC = Trail Camera *Reported by USFWS January 28, 2010 **Common refers to detecting daily during the trapping session

8 Mammal Inventory Report Crook Point, Oregon, 2009. Siskiyou Research Group

A comparison of abundance and diversity between the 4 largest vegetation types (polygons: 2,6,8,10) showed primarily P. maniculatus the most abundant species in all 4 polygons (Table 4). Species abundance and diversity per unit effort (trap night) suggested the forested vegetation types (polygons 2, 6) contained a greater diversity of small mammal species with the presence of Sorex. Polygon 10 (Open South Coast Headland Erosion Forblands and Dunes) supported the largest population of P. maniculatus when compared to results from other vegetation types. Polygon 8 (South Coast Headland Prairie) contained the smallest number of captures per unit effort. Detection of other small mammal species at Crook Point may be suppressed by the high rate of trap occupancy by P. maniculatus.

Table 4. Comparison of Species Abundance and Diversity Between 4 Largest Polygons, Crook Point, Oregon

Polygon # Trap nights Species Count 2 145 PEMA 40 SOVA 1 MILO 1 SOTR 1 TOTAL 145 4 43

6 165 PEMA 36 SOTR 4 SOVA 1 MUER 1 TOTAL 165 4 42

8 213 PEMA 29 MILO 3 THBO 1 TOTAL 213 3 33

10 204 PEMA 53 MILO 1 THBO 1 TOTAL 204 3 55

Discussion Results from genetic analysis suggest recent genetic divergence between the Saddle Rock Microtus longicaudus population and the mainland Crook Point M. longicaudus population (M. Miller, per comm.). It is possible the Saddle Rock population could further diverge over time given the pressures of a closed population and the island habitat. Germane to the possibility of a distinct population would be the consideration of life history and diet, specifically are these animals displacing or predating the nesting storm petrels. Verts and Carraway (1998), however, report M. longicaudus as largely a vegetarian species, so while the possibility of predation may be remote it warrants further investigation.

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Efforts to minimize animal mortality caused by trapping were inconclusive. I added nesting material and mealworms in the pitfall traps specifically for shrews. Nesting material in pitfalls was utilized by some animals (voles, shrews, deer mice) but I saw no evidence of predation on mealworms. Of the 9 shrews captured, 5 were dead and 2 were collected live. Of the 45 M. longicaudus captured 10 were dead. Of the 2 Mustela erminea captured, 1 was dead. P. maniculatus appear to be the hardiest to trapping, of the 236 individuals captured, only 5 were dead. The Sherman traps were not supplied with nesting material and while I made every effort to place these traps in protected locations and cover them with a cedar shingle, animal mortality still occurred – most likely from exposure. The best method for reducing trap related deaths is checking traps as early as possible. I would continue to add nesting material to pitfall traps but I would discontinue adding mealworms.

Recommendations Further investigation of life history and diet of the Saddle Rock population of Microtus longicaudus may determine if these animals are negatively affecting nesting storm petrels. Such a study would require the capture of individuals and the examination of stomach contents through the petrel nesting cycle.

I would recommend further small mammal sampling efforts, especially along the riparian habitats within the refuge. Several riparian-obligate species were not captured in this survey effort and more sampling could possibly document these species. When focusing on one or two specific habitat types I would suggest extending the trapping effort from 5 trap-nights per transect to 10 trap-nights per transect.

Small mammals difficult to identify in the field were collected for study skin and skull preparation for later identification. The purpose of this collection is to verify species identifications and provide specimens that may contribute to future studies. The animals I collected were frozen for later processing. I discovered that frozen specimens continue to degrade and study skin preparation becomes difficult after time due to the degradation of the specimens, this is especially true of shrews. In the future I would process collected specimens as soon as possible.

It has been suggested that the study skin and skull collection be donated to the Burke Museum of Natural History and Culture at the University of Washington, or The Museum of Vertebrate Zoology, University of California at Berkeley. This would give other researchers access to samples taken from Crook Point, especially samples which can be tied to additional studies such as the genetic work performed on the microtines of Crook Point.

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Acknowledgements I would like to express my gratitude to the following people whose time, talents, and material resources were of enormous value in the completion of this project: Thank you to Madeleine VanderHeyden, USFWS, who initiated this project and spent many hours in the field laying out transects and marking deer mice; to John Roth, National Park Service Oregon Caves National Monument, who loaned all the Sherman and Tomahawk live traps used in this study; to Doug Gomez who provided helpful suggestions and refinements to the study design; to Sandra Brown who designed and built the database where all the captured animals will reside; to Bill Gray who helped prepare study skins and skulls; to Dr. Karen Stone, Southern Oregon University, who opened the Vertebrate Natural Museum at SOU so that I may compare specimens for identification; to Dr. Steve Cross and Dr. Eric Forsman who helped identify microtines to species from skulls; and Dr. Bill Bridgeland, USFWS for reviewing this report.

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References

Anderson, J.T., Wildlife Marking Techniques, 2006. West Virginia University www.forestry.caf.wvu.edu/jAnderson/marking-techniques.pdf

Bilderback, David and Diane, 2008. Plant species occurrence at Crook Point Unpublished database, Bandon Marsh National Wildlife Refuge, Bandon, Oregon

Chan, R. 2001. Taxonomic changes and a new species in Lasthenia sect. Amphiachaenia (Compositae: Heliantheae sensu lato). Madroño 48(3): 205–210.

Gomez, Douglas, 2008. Small Mammal Survey for Camp Guernsey, Wyoming Colorado State University, Fort Collins, CO.

Jameson, E.W., Peeter, H.J., 2004. Mammals of California. University of California Press.

Kagan, J.S. 2002. Vegetation of Crook Point Unit Oregon Inlands National Wildlife Refuge, Curry County, Oregon. Oregon Natural Heritage Information Center. Portland, Oregon. Unpublished report for U.S. Fish and Wildlife Service, Bandon, Oregon.

Ledig, D. 2009, USFWS, Wildlife Refuge Manager, Bandon Marsh Unit, Oregon Islands Wildlife Refuge. Personal Communication.

Maser, Chris and Robert M. Storm, 1970. Microtinae of the Pacific Northwest.

Miller, M.P 2010.USGS Forest and Rangeland Ecosystem Science Center. Corvallis, Oregon.

Point Reyes Bird Observatory (PRBO), 2004. Saddle Rock Leach’s Storm-Petrel Project, http://www.prbo.org/cms/319.

Quayle, James, editor. 1998. Inventory Methods for Small Mammals: Shrews, Voles, Mice and Rats. Standard Components of British Columbia’s Biodiversity, No 31. Ministry Of Environment, Lands and Parks. Resource Inventory Branch for the Terrestrial Ecosystems Task Force, Resource Inventory Committee.

Verts, B.J., Carraway, L.N. 1998. Land Mammals of Oregon. University of California Press, Berkeley and Los Angeles, California

Wilson, D.E. et al, editors. 1996. Measuring and Monitoring Biological Diversity: Standard Methods for Mammals. Smithsonian Institution Press, Washington D.C.

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Zielinski, W.J., Kucera, T.E., technical editors. 1995. American Marten, Fisher, Lynx, and Wolverine: Survey Methods for Their Detection. Gen. Tech. Rep. PSW-GTR 157. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; 163 p.

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