Timothy H. Heaton and Frederick Grady chapter

The Late Wisconsin Vertebrate History of Prince of Wales Island, Southeast Alaska 2

Abstract Three caves have been extensively excavated and many others sampled for fossil vertebrates on Prince of Wales Island and surrounding islands of the Alexander Archipelago, Southeast Alaska. A diverse fauna of fishes, birds, and mammals has been identified spanning the past 50,000 years, though only mammal fossils have been adequately dated. Prior to the last glacial maximum, Marmota caligata, Phenacomys cf. P. intermedius, Lem- mus sibiricus, Alopex lagopus, Ursus arctos, Ursus americanus, Lontra can- adensis, Rangifer tarandus, and a bovid (cf. Saiga tatarica) lived on Prince of Wales Island. A sea ice fauna consisting of Phoca hispida, Phoca vi- tulina, Eumetopias jubatus, A. lagopus, and Vulpes vulpes was present during the glacial maximum, and U. arctos, U. americanus, L. canadensis, and R. tarandus may have survived on coastal refugia. All rodents were extirpated by the glacial maximum, and barriers delayed their eventual recolonization. Sea bird fossils occur in great abundance with A. lagopus until this fox was extirpated following the last glacial maximum. The modern forest community, dominated by Odocoileus hemionus, U. amer- icanus, Canis lupus, L. canadensis, Mustela vison, Mustela erminea, and Microtus longicaudus, developed during the latest Pleistocene and early Holocene. During this transition R. tarandus, U. arctos, V. vulpes, Gulo gulo, and Microtus cf. M. oeconomus died out on the island as new arrivals competed with previous inhabitants and the coastal rainforest became more fully established on the islands.

Introduction Until the 1990s, Southeast Alaska was ignored by Quaternary paleontol- ogists while spectacular finds were unearthed in eastern Beringia to the north and the midcontinental states to the south (Guthrie 1990; Kurte´n

17 and Anderson 1980). This was due to the belief that Ice Age glaciers covered virtu- ally all of the northwest coast of North America and consequently that all terres- trial vertebrates living in the region were postglacial immigrants (Klein 1965; Prest 1969; Nasmith 1970; Cwynar 1990; Mann and Hamilton 1995). A second reason was the lack of known fossil deposits in the dense coastal rainforest. A breakthrough was made in 1990 when cave explorers of the Tongass Caves Project, surveying the complex cave systems in the limestone of northern Prince of Wales Island, began discovering extensive vertebrate fossil de- posits. Prince of Wales Island is the largest island in Southeast Alaska, with a length of 220 km and an area of 5,780 square km, dominating the southern half of the Alex- ander Archipelago (Figure 2.1). All but the highest mountain peaks are covered by dense rainforest consisting of spruce, hem- lock, and cedar. About 85percent of the island com- prises the Thorne Bay and Craig Ranger Districts of Tongass National Forest. The climate is cool and wet but is kept com- paratively warm for a latitude of 55Њ by the Japan Current, which feeds the Gulf of Alaska. The terrain is rugged and glacier sculptured, and the island has 1,600 km of coastline. Smaller outer islands absorb most of the waves from the North Pacific, creating relatively quiet waters for the In- side Passage. Prince of Wales Island is only accessible by boat and plane. The usual connecting city is Ketchikan, and the near- est continental access road is at Prince Ru- Figure 2.1. Index map of the Alexander Archipelago, pert, British Columbia. The primary in- Southeast Alaska, and surrounding areas of British Co- dustries of the region are timber, fishing, lumbia. The star shows the area of Prince of Wales Island and tourism. where the majority of the caves we have studied are lo- Much of the northern half of Prince cated (from Heaton et al. 1996). of Wales Island has a bedrock of Paleozoic limestone. Weathering and dissolution has created a karst terrain where most of the drainage in limestone areas is underground. These well-drained karstlands support the largest timber and have been attractive areas for commercial logging. Many caves in logged areas have been severely damaged by slash and sedimentation, and some entrances have been buried by the building of logging roads. Clear-

18 TIMOTHY H. HEATON AND FREDERICK GRADY cut areas are nearly impenetrable because of dense, spiny vegetation (es- pecially devil’s club and young spruce) and rotting stumps and slash. Logging has greatly improved access to the area, however, and has re- sulted in the discovery of many previously unknown caves. The U.S. Forest Service, though mandated to assist with logging, has shown a great interest in the forest’s other resources and has provided extensive support for cave explorers and scientists (Baichtal et al. 1997). We began our study of fossil vertebrates in the Alexander Archipelago in 1991, and our excavations are still ongoing. In this chapter, we describe the primary cave sites, list our preliminary identifications of the fossils recovered, and give our current interpretations of the Ice Age history of vertebrates on Prince of Wales Island.

Description and Taphonomy of the Caves Taphonomically the cave deposits of Prince of Wales Island fall into three main categories: (1) den sites, (2) natural traps, and (3) fossiliferous wa- terlain sediments (Table 2.1). Some caves involve more than one of these processes. Below are descriptions of caves that have proven most signifi- cant and that we have excavated most extensively thus far.

El Capitan Cave The study of Ice Age vertebrates in Southeast Alaska began when a bone deposit was discovered in 1990 by cavers in El Capitan Cave, Alaska’s largest known cave with nearly 4 km of mapped passageways. This cave is located on the north side of a glacial valley that is now occupied by the El Capitan Passage—a shallow fjord that separates Prince of Wales Island from Kosciusko Island. The main portion of the cave is a long horizontal solution passage with a large room and a river in the back portion (called the Alaska Room). Lower passages of the cave flood during heavy runoff, creating a hazard to cavers.

Table 2.1. Cave Sites on Prince of Wales (POW) and Surrounding Islands in the Alexander Archipelago from Which Radiocarbon-Dated Vertebrate Remains Have Been Collected Island or Site Elevation Site Name Area Code (m) Cave Type 14Cyrb.p. 1 El Capitan Cave POW PET-190 130 Coastal den 12,295Ϫ5770 2 On Your Knees Cave POW PET-408 140 Coastal den Ͼ44,940Ϫ1990 3 Kushtaka Cave POW PET-410 50 Coastal den 9330Ϫ2820 4 Bumper Cave POW PET-407 520 Subalpine den 11,725Ϫ7205 5Blowing in the Wind Cave POW PET-220 670 Natural trap 9995 6 Tlacatzinacantli Cave POW — 200 Natural trap 10,970Ϫ5235 7 Devil’s Canopy Cave POW PET-221 180 Sedimentary Ͼ44,500 8 Broken Promise Cave Kuiu — 180 Natural trap 2230 9 Stadium Cave Kosciusko — 275Natural trap 260 10 Nautilus Cave Heceta CRG-462 170 Natural trap 8180Ϫ1580 11 Colander Cave Coronation — 200 Natural trap 11,630Ϫ3310 12 Enigma Cave Dall CRG-442 150 Coastal den 11,715 13 Puffin Grotto Noyes — 10 Sea cave 5115 14 Lawyers Cave Mainland — 30 Coastal den 8880Ϫ3050 15 Hole 52 Cave Mainland — 55 Natural trap 11,460Ϫ4395

Late Wisconsin History of Prince of Wales Island 19 Figure 2.2. Black bear skeleton in upper cham- ber of El Capitan Cave, Alaska.

In an upper level of El Capitan Cave, behind a sealed second en- trance, caver Kevin Allred found a complete skeleton of Ursus americanus (black bear), parts of several other bears, and an accumulation of ground fish bone scattered on the rocky and muddy floor of the narrow solution passage (Figure 2.2). We first visited this site in 1991, and in 1992 we reopened the sealed entrance and conducted an extensive excavation (Heaton and Grady 1992, 1993). Radiocarbon dates revealed a latest Pleistocene to early Holocene age for the assemblage. The most spectacular discovery was remains of Ursus arctos (brown bear), a species never thought to have inhabited Prince of Wales Island. Two other extralimital species, Vulpes vulpes (red fox) and cf. Gulo gulo (wolverine), were also recovered, as were a variety of mi- cromammals, the most abundant being Microtus longicaudus (long-tailed vole). The upper passage of El Capitan Cave is typical of the den sites we have investigated. So is Kushtaka Cave, located farther south on the El Capitan Passage, and Bumper Cave (described on p. 21). These caves (or the fossiliferous portions thereof) have nearly identical structures; they are small in size (Յ40 m long and mostly 1–2 m in diameter), nearly hori- zontal, lack energetic streams, and have small entrances (about 0.5m diameter). Most of these caves appear to have been popular den sites for a variety of carnivores, particularly bears, otters, and foxes. Kushtaka Cave contains a modern otter nest made of sticks and has accumulated fresh otter dung since our first visit, so the use of these cave dens continues to the present day. Both El Capitan Cave and Kushtaka Cave contain thick beds of fish bone derived from otter scat, and bones of juvenile Lontra canadensis (river otter) have been found in the El Capitan Cave den. A late Holocene bone deposit containing juvenile L. canadensis and associated fish bone has also been found 60 m inside the main entrance of El Capitan Cave, demonstrating that portions of this cave still serve as an otter den.

20 TIMOTHY H. HEATON AND FREDERICK GRADY Several late Pleistocene bones have been found high in vertical ceil- ing passages of the Alaska Room in El Capitan Cave, 34 m above the floor, during explorations by caver Peter Smith. These late Pleistocene remains include a complete radius of Rangifer tarandus (caribou) and a large rib that matches U. arctos. These bones must have fallen in through one of several now-plugged sinkholes on the mountainside above the cave and therefore represent a natural trap deposit. Cavers also recovered parts of two juvenile skeletons of U. arctos from a deep pit high on El Capitan Peak called Blowing in the Wind Cave.

Bumper Cave The second cave, in which a significant bone deposit was discovered on Prince of Wales Island, was Bumper Cave, located high in a subalpine forest. One of us (Heaton) excavated this cave in 1994 with the help of David Love and other cavers. This cave is only 40 m long and is a typical bear den with a narrow, horizontal crawlway. The fauna dates to the latest Pleistocene and early Holocene. Recovered were the remains of at least twelve individuals of U. arctos, the first evidence of R. tarandus on the island, and M. longicaudus (Heaton and Love 1995; Heaton et al. 1996; Figure 2.3). The exceedingly low diversity found in the Bumper Cave fossil de- posit is attributed to three factors related to the cave’s location: it is on an island, at a high latitude, and at a high elevation. Whereas coastal dens like El Capitan Cave usually contain remains of U. americanus, U. arctos, L. canadensis, and a variety of marine fish, subalpine caves like Bumper and Blowing in the Wind caves contain only U. arctos from this assemblage. Subalpine caves are located too far from the rich resources of the ocean for most coastal feeders to live or den there. Den sites like Bumper Cave show a decreasing amount of animal activity from the entrance to the back of the passage, which is clearly il- lustrated by the distribution and condition of the fossil bones. The deeper parts of such caves contain the oldest remains, the most complete skel-

Figure 2.3. Brown bear skeleton in the back room of Bumper Cave, Alaska. Photo- graph by David Love.

Late Wisconsin History of Prince of Wales Island 21 etons, and the least broken, chewed, and weathered bones. A nearly com- plete and unburied skeleton of a late Pleistocene bear was recovered in near perfect condition at the very rear of the bone deposits in both El Capitan and Bumper caves with many of the elements laid out in ar- ticulated positions (Figures 2.2, 2.3). The undisturbed nature of these very old skeletons suggests that ventures beyond the light zone by car- nivores must have been rare. Nearer the entrance, the bones are much more disarticulated by subsequent bioturbation and are mixed with rocks, sticks, and roots. Bear bones in the entrance room of Bumper Cave are fragmentary and weathered, and they appear to be derived from many different individuals. Much can be learned about the life histories and habits of denning carnivores by studying the use of these attractive cave dens.

Devil’s Canopy Cave Devil’s Canopy Cave is located near the El Capitan Passage in an upland area between El Capitan and Kushtaka caves. It has a 7-m deep pit en- trance with a small surface stream disappearing into it. This stream me- anders down a deeply incised erosional passage for 35m before disap- pearing in a sump. Seven meters above the sump is an upper chamber left dry by the down-cutting stream. In this room is a bedded silt deposit that appears to have once filled the chamber. In 1992 an incisor of Mar- mota cf. M. caligata (hoary marmot), dating beyond the radiocarbon limit, was discovered in loose silt derived from this deposit (J. F. Baichtal and J. A. Cook, pers. com.). We screened sediment from this silt in 1994– 1998 and recovered a M. caligata molar and remains of Peromyscus cf. P. keeni (Keen’s mouse) and Sorex cf. S. monticolus (dusky shrew). Apparently these fossils were washed into the cave from an unknown source and were sorted along with the sediments, possibly during a period of glacial melting. This makes their taphonomic history difficult to inter- pret. However, this type of burial has the advantage of preserving bones for long periods of time and through the severe climatic changes that the island has experienced, thus opening a window to the island’s fauna prior to the last glacial maximum.

On Your Knees Cave By far the most significant cave deposit discovered to date in the Alex- ander Archipelago is On Your Knees Cave, located at the northern tip of Prince of Wales Island. This cave was discovered during a logging survey in 1993, and bones were discovered by caver Kevin Allred while surveying the cave. One of us (Heaton) made brief visits to the cave in 1994 and 1995. The cave was found to contain U. arctos and U. americanus remains predating the last glacial maximum and Phoca hispida (ringed seal) remains dating to the glacial maximum itself. A thick deposit of fossiliferous sediment made this cave particularly attractive for excavation, despite its remote location (Heaton 1995a, 1996a, 1996b; Heaton et al. 1996). The cave has a total length of 70 m, divided between two crawlway passages that we have named the Bear Passage and Seal Passage (Figure 2.4). We spent the summers of 1996 through 2000 conducting an extensive

22 TIMOTHY H. HEATON AND FREDERICK GRADY excavation of On Your Knees Cave, and the laboratory work is ongoing. After mak- ing cultural discoveries in 1996, we were joined by an archaeological team led by E. James Dixon of the Denver Museum of Nature & Science (formerly known as the Denver Museum of Natural History). His work has centered around the cave en- trance, whereas our work has focused on the narrow crawlways and low-ceiling rooms inside the cave (Dixon 1999; Dixon et al. 1997). This site has revealed many additional species records and is helping to establish a complete vertebrate faunal his- tory for Prince of Wales Island over the past 50,000 years (Heaton and Grady 1997, 1998, 2000). On Your Knees Cave is more complex and more difficult to classify than the other sites. It has virtually all the characteristics of a den site described above for El Capi- tan and Bumper caves, and it has obviously been used as a den throughout the late Pleistocene and Holocene by the usual coastal carnivores. Yet unlike most other sites, where subsurface deposits quickly be- come barren with depth, On Your Knees Figure 2.4. Frederick Grady in the Bear Passage of On Cave is filled with richly fossiliferous Pleis- Your Knees Cave, Alaska. tocene sediments from the surface to the bedrock floor. These deep sediments are almost entirely inorganic and very poorly sorted, and their exact origin is unclear. The bulk of them may have been deposited during one or more glacial melting or landslide events. As at Devil’s Canopy Cave, the full taphonomic history of the fossils contained in these sediments is difficult to assess. To complicate matters, these late Wisconsin fossils have been eroding out of the cave floor and mixing, through stream action and bioturbation, with younger postglacial bones. The Bear Passage contains a small stream and has clearly experienced multiple cut and fill cycles, and some of the most significant fossil remains have come from these complex, fluvially reworked sediments. However, a useful biostratigra- phy is emerging from several parts of the cave (Heaton and Grady, in press). The late Wisconsin bones recovered from On Your Knees Cave range from durable fragments, abraded and rounded beyond recognition, to fragile elements in excellent condition. About half of the larger bones are of birds and represent the only substantial fossil avifauna known from the island. Many of the bones, both of birds and mammals, have distinct puncture and gnaw marks from mammalian carnivores. We believe that the cave served as a carnivore den both before and during much of the last glacial maximum but that many of the bones were reworked and

Late Wisconsin History of Prince of Wales Island 23 buried during depositional events when glacially derived sediments en- tered the cave. The cave has continued to serve as a carnivore den throughout the postglacial period, with little deposition or disturbance, and—perhaps because of this—has attracted repeated attention from pre- historic humans (Dixon 1999; Dixon et al. 1997; Fedje et al., in press). The usefulness of this cave as a den site is clearly the reason for the spectacular accumulation of bone, but the factors that have buried the bones and preserved them through the last glacial maximum are more fortuitous and complex.

Tlacatzinacantli Cave The karst of Prince of Wales Island contains deep surface pits including the 182-m deep El Capitan Pit, the deepest limestone pit in the United States. A few of these natural traps contain prehistoric fossils, primarily postglacial bears and cervids. Some of the remains are very deep in these caves and can be accessed only by negotiating multiple pits, stream pas- sages, and crawlways. Blowing in the Wind Cave (aforementioned), Enigma Cave (on Dall Island), and Colander Cave (on Coronation Is- land) have produced nearly complete U. arctos skeletons, and a sinkhole above El Capitan Cave apparently captured at least one individual of U. arctos and R. tarandus. These remains all date to around the latest Pleis- tocene. Recent remains of Odocoileus hemionus (mule deer) have been found at the bottom of several other pits in the archipelago. Tlacatzinacantli Cave (Zina Cave for short) is a complex pit cave located in the central part of Prince of Wales Island. This cave has a large pit entrance that has served as a natural trap, and the cave itself is a series of vertical and horizontal passages comprising multiple levels. In 1998 a skeleton of O. hemionus with unusual antlers was discovered in an upper level of the cave and was dated at 8000 yr b.p. (Figure 2.5).

Figure 2.5. Deer skull with unusual antlers in Tlacatzinacantli Cave, Alaska. Photograph by James Baichtal.

24 TIMOTHY H. HEATON AND FREDERICK GRADY This is the oldest O. hemionus dated from the island, and its unusual nature could represent a founder effect. Portions of two other deer with younger radiocarbon dates were also found in the cave. Several U. americanus skulls and bones dating to the latest Pleisto- cene were also found in Tlacatzinacantli Cave, mostly in deeper levels. One skeleton found at the bottom of a 20-m deep pit had every major bone shattered from the fall. But downstream from this skeleton, caught behind a chalkstone in the middle of an active streambed, was a U. americanus skull in near perfect condition. How a skull could reach such a deep level in a vertical cave and be washed down a stream without damage is unknown. Although natural traps have not been our most productive excava- tion sites thus far, they have helped to fill in the ungulate record, which is seriously under-represented in the den sites and sedimentary deposits.

Other Caves Puffin Grotto is a sea cave on Noyes Island with a chamber that has been abandoned by isostatic uplift of the island following the last glacial max- imum. A whale vertebra dating to the middle Holocene was found in this chamber along with fish bones deposited later by otters (Heaton 2001a). The date on this eroded vertebra probably represents the final period of waves entering the back of this sea cave. Natural trap caves containing deer and bear bones have been located on several different islands (Table 2.1). Caves on Dall and Coronation islands hold special promise because they contain late Pleistocene re- mains and are located in areas that appear to have been coastal refugia during the Ice Age (Heaton, 2002). Two caves containing bone deposits have also been found on the Alaskan mainland southeast of the town of Wrangell. These caves are important because they provide an early record of postglacial colonization. Among other things, they contain a much more diverse rodent fauna than any of the island sites, including the only fossil record of Erethizon dorsatum (porcupine), Clethrionomys (red- backed vole), and Synaptomys (bog lemming) known from Southeast Alaska (Heaton 2001b, 2001c). These sites on the outer islands and the mainland will be excavated over the next few years to expand on the research that began on Prince of Wales Island. Most of the caves listed in Table 2.1 are discussed herein. Some sites, such as Blowing in the Wind, Enigma, and Nautilus caves, we have never visited ourselves, but bones have been collected and turned over to us for study by cavers and Forest Service scientists.

Methods Our goal has been to document the exact location and orientation of each recovered bone and to carefully remove all fossil remains from any sediment disturbed by our excavations. The tight quarters of most of the fossiliferous passages and the cold, wet, and muddy conditions of the caves of Southeast Alaska have often made these tasks difficult, but we have developed techniques that work well under these conditions.

Late Wisconsin History of Prince of Wales Island 25 Sites such as El Capitan Cave and Bumper Cave had extensive skel- etal material exposed on the cave floor and buried in shallow surface sediments. We photographed the exposed remains then established a two- dimensional grid system over the fossiliferous floor areas. Large bones, whether exposed or buried, were sketched on a map, assigned field num- bers, and recorded according to grid location and depth below the sedi- ment surface. Sediments were sampled from the more productive areas according to their grid location and depth, and they were removed from the caves in large plastic bags (about 4 kg per sample). In On Your Knees Cave, which lacked extensive surface bone but contained thick fossilif- erous sediments, a more sophisticated three-dimensional grid system was established for each room or passage and was controlled with line levels. In Devil’s Canopy Cave, where the fossiliferous sediments were eroding from a vertical bank, we also set up a three-dimensional grid that was used to record fine stratigraphic intervals during sediment removal. In crawlways so narrow that a coordinate grid system was not feasible, we sometimes simply measured a distance down a passage from a landmark and then used the relative position within the passage and the depth below the surface to approximate the location. The cave sediments were generally unconsolidated and easy to re- move with a trowel. Grain sizes varied from the finest clays to cobbles and boulders, and sediments varied from well sorted to very poorly sorted. Bone concentrations varied from zero in barren clays to nearly 100 per- cent in bedded deposits of fish remains. Rocks were the biggest obstacles to excavation. Localized cementation of sediment also made excavation difficult in a few places in On Your Knees Cave, though this was rare. We removed large rocks as we collected sediments to reduce weight and damage to bones. Such rocks were scraped clean and either piled in the cave or removed separately. We generally excavated sediment in 30-cm squares and 5-cm vertical levels. A strip of flagging tape with the sample number and coordinates recorded on it was inserted in each bag of sed- iment for inventory tracking. Our washing method has varied somewhat depending on available water. We generally washed the sediments as close to the collection site as possible to avoid the difficulty of transporting them through the forest. Initially a pressurized sprayer was available, and we emptied each bag of sediment onto a stack of three 0.5-m-wide screens (coarsest on top) and sprayed water from above, catching the finest fraction (Ͻ1 mm) in buck- ets and screening it with mosquito net bags. This method was not always successful in breaking down the finer clays, however, and we also expe- rienced damage to rodent teeth from the high-pressure water. At other times, only stored water or ocean water was available, and we simply emptied each bag of sediment into a mosquito net bag and manipulated it by hand in buckets of water until all the clay and silt (Ͻ0.5mm) was washed clean. This process took up to thirty minutes per sample, but fragile bones and teeth survived remarkably well. Thus, this became our preferred method. Although some sediments were examined and discarded in the field, most were shipped to the laboratory for further processing. At On Your Knees Cave in 1998 through 2000, when we processed more than

26 TIMOTHY H. HEATON AND FREDERICK GRADY 5,000 bags of sediment, we dried the samples on cardboard flats over kerosene heaters then screened them through 5mm mesh to remove the coarsest fraction. Large, delicate, or diagnostic bones were removed during this process and immediately assigned field numbers, facilitated by a computer database that links fossils to the corresponding sediment samples. The remaining finer sediments were shipped to the laboratory to be dry-screened into fractions and searched for bone under magnifi- cation. Teeth of the smallest rodents and shrews were recovered by this process. The fossils we have collected are currently housed at the University of South Dakota but will be permanently curated at the University of Alaska Museum in Fairbanks. We have taken collections to the Smith- sonian Institution, the American Museum of Natural History, the Field Museum of Natural History, the Denver Museum of Nature & Science, the University of Alaska, the University of Victoria, the University of Ne- braska, and several smaller museums for detailed identification and study using comparative collections. Our work has grown into a collaborative effort with many active re- searchers. E. James Dixon, Terence E. Fifield, and Robert A. Sattler are working closely with us studying archaeological remains and depositional processes at the caves (Dixon et al. 1997). David E. Putnam and James F. Baichtal have been studying the sea level history of Prince of Wales Island, and Thomas D. Hamilton has investigated the glacial history (Baichtal et al. 1997). Thomas A. Ager has initiated a pollen study on the island using peat deposits and lake cores, and both he and Rolf W. Ma- thewes have extracted minor pollen samples from our cave sediments. Our fish specimens have been identified by Susan J. Crockford and Re- becca J. Wigen of Pacific Identifications, Inc., using comparative collec- tions at the University of Victoria.

Radiocarbon Dates and Isotopic Analysis The preponderance of the fossil deposits are early postglacial in age, span- ning the Pleistocene-Holocene boundary. We therefore have good docu- mentation for the species that inhabited the island at that time, which consists of the island’s modern terrestrial fauna (minus Canis lupus, wolf) plus several extirpated species. Only On Your Knees Cave covers the period of the last glacial maximum and the interval preceding it that is within the range of radiocarbon dating. The faunal differences between the various climatic periods are substantial, as discussed later. It appears that some species survived the last glaciation in the region while others did not, and later there was a turnover in species as Prince of Wales Island underwent a transition from tundra to the modern rainforest. Radiocarbon dates have provided an age range for each of the cave deposits and in some cases are numerous enough to document the full time range of individual species. Table 2.2 lists the radiocarbon dates obtained thus far from bone collagen. Most of the dates were performed by geochronology laboratories at the University of Arizona at Tucson, and the University of Colorado at Boulder. An unexpected benefit of radiocarbon dates has been the insights

Late Wisconsin History of Prince of Wales Island 27 Table 2.2. Radiocarbon Dates Obtained on Bones from Caves of Prince of Wales and Nearby Islands of Southeast Alaska 14Cyrb.p. Lab Code and Error Site1 Species Element 509Odocoileus hemionus TibiaעAA-32121 260 Castor canadensis Limb bone 10 60עAA-36642 1580 Lontra canadensis Skull 952עAA-21568 1990 Odocoileus hemionus Dentary 8 40עSR-5263 2230 cf. Ursus americanus Artifact 3 60עCAMS-27263 2790 Unknown Artifact 14 40עSR-5420 3050 Lontra canadensis Limb bone2 1 60עAA-10450 3290 5011Odocoileus hemionus HumerusעAA-44451 3310 502Ursus americanus DentaryעCAMS-31068 3960 Erethizon dorsatum Skull 15 70עAA-36639 4395 Ursus americanus Skull 15 60עAA-36637 4845 Cetacea Atlas 13 100עAA-21563 5115 Odocoileus hemionus Pelvis 2 60עCAMS-31069 5210 Odocoileus hemionus Metacarpal 756ע AA-321155235 Osteichthyes Fish bone2 1 130עBT-55709 5770 cf. Eumetopias jubatus Artifact 2 40עCAMS-42382 5780 5014Ursus americanus PhalanxעSR-5265 6290 Ursus americanus Skull 1 130עAA-10447 6415 Osteichthyes Fish bone 651עAA-10449 6810 Lontra canadensis Skull 651עAA-37877 7045 Ursus arctos Dentary 654עAA-15224 7205 Odocoileus hemionus Metatarsal 6 120עAA-32116 7630 Odocoileus hemionus Femur3 6 90עAA-32114 7850 506Odocoileus hemionus Calcaneum3עSR-5109 8000 Odocoileus hemionus Humerus 10 70עAA-10574 8180 Osteichthyes Fish bone 1 70עAA-11514 8535 Ursus americanus Rib 3 60עCAMS-24967 8630 5014Melanitta fusca CoracoidעSR-5264 8880 Ursus americanus Femur 3 155עAA-18451R 9330 Homo sapiens Dentary4 2 60עCAMS-29873 9730 Ursus arctos Humerus 751עAA-07794 9760 502Homo sapiens Pelvis4עCAMS-32038 9880 Ursus arctos Ribs 955עAA-10451 9995 Ursus americanus Femur 6 110עAA-32118 10,020 Vulpes vulpes Dentary 1 100עAA-33797 10,050 Ursus americanus Phalanx 15 120עAA-36641 10,080 Ursus americanus Phalanx 2 160עAA-33780 10,090 cf. Ursus americanus Artifact 2 50עCAMS-42381 10,300 Ursus americanus Skull 15 100עAA-36636 10,350 Ursus americanus Skull 15 110עAA-36640 10,420 Rangifer tarandus Metacarpal 4 110עAA-18449R 10,555 Ursus americanus Humerus 751עAA-07793 10,745 Ursus americanus Skull 6 120עAA-32120 10,860 Ursus americanus Ulna 6 120עAA-32117 10,870 Ursus americanus Skull 15 140עAA-36638 10,930 Ursus arctos Molar 854עAA-15225 10,970 Ursus americanus Fragment 6 120עAA-32119 10,970 Ursus arctos Humerus 4 110עAA-15223 11,225 Alopex lagopus Pelvis 2 90עAA-21567 11,275 Ursus americanus Canine 15 130עAA-33202 11,460 Ursus americanus Skull 1 110עAA-10446 11,540 Rangifer tarandus Radius2 1 100עAA-33201 11,560 Ursus americanus Skull 1151עAA-10448 11,565 Ursus arctos Humerus 11 120עAA-44450 11,630 Ursus arctos Rib 4 80עAA-15222 11,640

28 TIMOTHY H. HEATON AND FREDERICK GRADY Table 2.2. Radiocarbon Dates Obtained on Bones from Caves of Prince of Wales and Nearby Islands of Southeast Alaska (continued) 14Cyrb.p. Lab Code and Error Site1 Species Element Ursus arctos Humerus 12 120עAA-15226 11,715 Ursus arctos Rib2 1 140עAA-32122 11,910 Ursus arctos Pelvis 1 120ע AA-1044512,295 Alopex lagopus Radius 2 140עAA-36649 12,700 Phoca hispida Humerus 2 240עAA-21564 13,690 Phoca hispida Skull 2 470עAA-36661 14,520 Phoca hispida Femur 2 240עAA-37873 17,130 Phoca hispida Skull 2 270ע AA-4444517,740 Phoca hispida Tibia 4652עAA-37874 17,805 Phoca hispida Radius 2 230עAA-37878 18,085 Phoca hispida Vertebra 2 350עAA-36662 18,770 Phoca vitulina Dentary 2 280עAA-36658 18,860 Phoca hispida Skull 2 310עAA-36659 18,920 Phoca hispida Ulna5 2752עAA-18450R 19,060 Alopex lagopus Rib 2 210עAA-33794 19,170 Phoca hispida Metacarpal 2 260עAA-36666 19,240 Vulpes vulpes Canine 2 320עAA-33793 19,480 Phoca hispida Dentary 2 350עAA-33788 19,830 Phoca hispida Humerus 2 500עAA-22884 20,060 Phoca hispida Skull 2 280עAA-33789 20,110 Eumetopias jubatus Canine 2 450עAA-33790 20,170 Phoca hispida Ulna 2 270ע AA-3378520,210 Phoca hispida Metacarpal 2 360עAA-36667 20,300 Phoca hispida Skull 2 660עAA-36660 20,470 Melanitta fusca Humerus 2 330עAA-33197 20,530 Phoca hispida Ulna 2 710עAA-36664 20,540 Phoca hispida Navicular 2 520עAA-33784 20,550 Phoca hispida Ulna5 2 80עCAMS-33980 20,660 Alopex lagopus Metacarpal 2 520עAA-36646 20,690 Phoca vitulina Tibia 2 350עAA-36657 20,720 Eumetopias jubatus Premolar 2 650עAA-36651 20,820 Phoca hispida Metacarpal 2 480עAA-36668 20,880 Phoca hispida Skull 31152ע AA-3787521,385 Phoca hispida Skull 2 400עAA-44444 22,160 Phoca hispida Metatarsal 2 300עAA-33787 22,490 Vulpes vulpes Humerus 2 640ע AA-3664523,120 Phoca hispida Phalanx 2 470עAA-33786 23,260 Phoca hispida Skull 8652עAA-37876 23,315 Marmota caligata Incisor 2 770עAA-21566 23,560 Phoca hispida Phalanx 2 490ע AA-3666524,150 Fratercula sp. Humerus 2 610עAA-36643 26,030 Rangifer tarandus Antler 2 680עAA-33193 26,670 Ursus arctos Astragalus 2 700עAA-33783 26,820 Marmota caligata Skull 2 1600עAA-32123 27,300 Marmota caligata Skull 2 660עAA-33796 27,750 Ursus americanus Calcaneum 2 360עAA-21569 28,695 Ursus americanus Vertebra 2 400עAA-21570 29,820 Ursus arctos Molar 2 1900עAA-33792 31,700 cf. Saiga tatarica Horn core 2 2200עAA-22883 32,000 Marmota caligata Incisor 2 2400עAA-21565 32,900 Uria aalge Sternum 2 1600עAA-33192 33,200 Marmota caligata Humerus 2 1600עAA-33191 33,600 cf. Saiga tatarica Molar 2 3000עAA-44442 34,100 Ursus arctos Femur 2 800עAA-15227 35,365 Ursus americanus Femur 2 2300עAA-33781 36,770

Late Wisconsin History of Prince of Wales Island 29 Table 2.2. Radiocarbon Dates Obtained on Bones from Caves of Prince of Wales and Nearby Islands of Southeast Alaska (continued) 14Cyrb.p. Lab Code and Error Site1 Species Element Rangifer tarandus Unciform 2 510עSR-5168 36,980 Phoca vitulina Dentary 2 2200ע AA-3379537,700 Rangifer tarandus Metapodial 2 580עSR-5476 37,990 Ursus americanus Humerus 2 3000עAA-33194 38,400 Ursus americanus Rib 2 3100עAA-33198 39,000 cf. Ursus arctos Tooth 2 3100עAA-33791 39,400 Clangula hyemalis Humerus 2 3000עAA-33782 39,500 Ursus americanus Tibia 2 1500עAA-16831 41,600 AA-36656 21,000ϩ 2 Phoca vitulina Pelvis AA-36653 25,000ϩ 2 cf. Ursus americanus Premolar AA-36655 27,000ϩ 2 cf. Ursus americanus Baculum AA-36648 32,000ϩ 2 Alopex lagopus Metacarpal AA-44443 34,000ϩ 2 cf. Saiga tatarica Molar AA-36644 35,000ϩ 2 Fratercula sp. Humerus AA-36650 35,000ϩ 2 Alopex lagopus Dentary AA-36647 36,000ϩ 2 Alopex lagopus Metatarsal AA-33196 38,500ϩ 2 Ursus americanus Scapula AA-33200 39,400ϩ 2 Ursus americanus Canine AA-44447 39,900ϩ 2 Marmota caligata Pelvis AA-3319540,100 ϩ 2 Ursus americanus Humerus AA-33199 40,200ϩ 2 Ursus americanus Canine AA-44446 41,000ϩ 2 Alopex lagopus Molar AA-44448 41,000ϩ 2 Ursus americanus Molar AA-44449 41,000ϩ 2 Uria aalge Humerus SR-5110 43,050ϩ 2 Ursus americanus Vertebra AA-08871A 44,500ϩ 7 Marmota caligata Incisor SR-5111 44,940ϩ 2 Ursus americanus Skull 1See Table 2.1 for a key to the site numbers. 2These samples are not from the upper level of El Capitan Cave where the main excavation took place. 3These samples are from the same individual of Odocoileus hemionus (with the odd antlers). 4These samples are from the same individual of Homo sapiens (Dixon et al. 1997). 5These samples are from the same individual of Phoca hispida, as was a previous incorrect date (Heaton, Talbot, and Shields 1996; Heaton and Grady 1997).

gained from δ13C values used as corrections in the dating process (Heaton 1995b). In addition, we have submitted some fossil and modern bone samples from Prince of Wales Island to the isotope laboratory at Augus- tana University, Sioux Falls, South Dakota, for more extensive carbon and nitrogen stable isotope analysis (Champe and Heaton 1996). Plants select carbon isotopes from their environment in unique ratios, and these isotopic signatures are passed on with predictable modifications to higher levels in the food web. This makes it possible to determine an animal’s ultimate dietary source. The Alexander Archipelago closely ap- proximates a simple two-food source model like the one outlined by Fry

and Sherr (1984). Terrestrial plants of northern latitudes use C3 photo- 13 0 synthesis and yield δ C values averaging Ϫ27 ⁄00 (Tieszen and Boutton 13 0 1988), with a δ C enrichment to approximately Ϫ21 ⁄00 in the bone collagen of animals getting their food from terrestrial plant sources (Fig- ure 2.6). Marine plants have much higher δ13C values, and the bone

30 TIMOTHY H. HEATON AND FREDERICK GRADY Figure 2.6. Diagram of expected and actual δ13C values on colla- gen from selected fos- sil and modern verte- brate bones and teeth from Southeast Alaska. Stars indicate the sin- gle samples, and num- bers indicate multiple samples with the same value. For a discussion of the human remains, see Dixon (1999) and Dixon et al. (1997).

collagen of marine fishes and other marine feeders averages Ϫ130⁄00. Varations about these representative values rarely exceeds 30⁄00, so animals feeding from the ocean and the land can easily be discriminated. This provides important data for ecological reconstruction. Three early Holocene fish bone samples from El Capitan Cave have yielded δ13C values spanning the expected range for marine feeders (Fig- ure 2.6; Table 2.3). Other species that appear to have been exclusive marine feeders based on their δ13C values are otters, seals, whales, and early humans. Terrestrial herbivores such as artiodactyls and rodents registered δ13 much lower C values, indicative of their C3 plant diets. Most of these results are logical, based on the known feeding habits of these species. The more interesting results are on omnivores such as bears. Although Ursus americanus is known to do some salmon fishing on Prince of Wales Island today, δ13C values on both fossil and modern specimens suggest a completely terrestrial diet. Values from fossil Ursus arctos from the island, by contrast, have fallen in the intermediate range, so they must have eaten roughly equal amounts of marine and terrestrial food (Heaton 1995b). The same appears true for Alopex lagopus (arctic fox). One curiosity is the extremely low δ13C values for Odocoileus hem- ionus and Castor canadensis (beaver), falling outside the expected range and differing markedly from the other herbivores (Figure 2.6; Table 2.3). Such low values are common in dense canopy forests. In such forests carbon dioxide is recycled and depleted in carbon-13: Plant litter falls to the forest floor, carbon dioxide is released through decomposition, and the trees reabsorb (and reselect) it because there is inadequate air circu- lation between the understory and the atmosphere (van der Merwe and Medina 1991). O. hemionus is a forest feeder and may not have colonized the island until the dense rainforest developed (see Table 2.2 for radio- carbon ages). Rangifer, Saiga, and Marmota, by contrast, prefer open tundra or prairie where closed carbon dioxide recycling does not occur; therefore, they have higher δ13C values.

Late Wisconsin History of Prince of Wales Island 31 Table 2.3. δ13C Values from Prince of Wales Island by Taxon in Order of Mean Value Taxon N Spread Minimum Mean Maximum Terrestrial Feeders Castor canadensis 1 0.0 Ϫ25.7 Ϫ25.7 Ϫ25.7 Odocoileus hemionus 8 3.2 Ϫ26.0 Ϫ24.6 Ϫ22.8 Erethizon dorsatum 1 0.0 Ϫ23.0 Ϫ23.0 Ϫ23.0 Marmota caligata 7 3.5 Ϫ24.5 Ϫ22.4 Ϫ21.0 Ursus americanus 44 5.2 Ϫ23.6 Ϫ20.7 Ϫ18.4 Saiga tatarica 3 2.2 Ϫ20.3 Ϫ19.4 Ϫ18.1 Rangifer tarandus 4 1.2 Ϫ19.4 Ϫ19.0 Ϫ18.2 Mixed Feeders Ursus arctos 17 3.6 Ϫ19.5 Ϫ17.5 Ϫ15.9 Alopex lagopus 8 7.1 Ϫ18.9 Ϫ15.5 Ϫ11.8 Vulpes vulpes 3 4.7 Ϫ18.0 Ϫ15.2 Ϫ13.3 Marine Feeders Cetacea (great whale) 1 0.0 Ϫ14.5 Ϫ14.5 Ϫ14.5 Sea birds 6 3.5 Ϫ15.7 Ϫ14.1 Ϫ12.2 Eumetopias jubatus 3 1.1 Ϫ14.2 Ϫ13.6 Ϫ13.1 Marine fishes 3 5.0 Ϫ16.1 Ϫ13.5 Ϫ11.1 Phoca hispida 254.7 Ϫ16.1 Ϫ13.2 Ϫ11.4 Phoca vitulina 4 4.7 Ϫ15.3 Ϫ12.5 Ϫ10.6 Homo sapiens1 2 0.4 Ϫ12.5 Ϫ12.3 Ϫ12.1 Lontra canadensis 3 2.6 Ϫ12.6 Ϫ11.6 Ϫ10.0 1Both values from the same individual. For discussion of the archaeological record, see Dixon (1999) and Dixon et al. (1997).

Composition of the Fauna Table 2.4 lists the taxa identified thus far from caves of Prince of Wales Island and a few smaller islands to the west. The table also indicates which species are present on the island today, including introduced spe- cies. Some of the identifications are preliminary, especially on the fish and birds. A more complete systematic analysis will appear in the future.

Fish Den-type caves that we examined within 1 km of the ocean contained abundant fish bone, often in thick concentrations (5–20 cm). The bones were generally ground up and fragmentary from having been chewed, and their abundance in the sediments sometimes made the search for small mammals and birds tiresome. We contacted many colleagues before finding researchers who were able and willing to identify these remains. Susan J. Crockford and Rebecca J. Wigen of Pacific Identifications, Vic- toria, British Columbia, are experts in identifying fish remains from the Pacific Coast, including those from a wide range of marine mammal feces, and they have made the fish identifications listed in Table 2.4. Based on the species list, the elements preserved and their condition, the size distribution within species, and the inclusion of tiny fragments of marine invertebrates, it is our firm conclusion that the fish remains are predominantly or exclusively derived from feces of Lontra canadensis. Studies of modern otter excreta have been made in Southeast Alaska and have produced species lists similar to ours (Home 1982; Larsen 1983, 1984; Woolington 1984).

32 TIMOTHY H. HEATON AND FREDERICK GRADY Table 2.4. Preliminary List of Taxa Recovered from Caves of Prince of Wales Island, Alaska Currently Living on Abundant in Taxon Common Name Prince of Wales Island1 Cave Faunas2 Class Osteichthyes Order Clupeiformes Family Clupeidae Clupea pallasi Pacific herring X — Order Salmoniformes Family Osmeridae Mallotus villosus Capelin X — Thaleichthys cf. T. pacificus Eulachon X — Family Salmonidae Oncorhynchus sp. Salmon X — Order Gadiformes Family Gadidae Gadus macrocephalus Pacific cod X — Microgadus cf. M. proximus Pacific tomcod X — Theragra chalcogramma Walleye pollack X — Order Gasterosteiformes Family Gasterosteidae Gasterosteus aculeatus Threespine stickleback X — Order Scorpaeniformes Family Scorpaenidae Sebastes sp. Rockfish X X Family Anoplopomatidae Anoplopoma fimbria Sablefish X — Family Hexagrammidae Hexagrammos cf. H. decagrammus Kelp greenling X — Hexagrammos cf. H. lagocephalus Rock greenling X — Hexagrammos cf. H. stelleri Whitespotted greenling X — cf. Ophiodon elongatus Lingcod X — Family Cottidae cf. Artedius fenestralis Padded sculpin X — Cottus aleuticus Coastrange sculpin X — Cottus cf. C. asper Prickly sculpin X — Enophrys bison Buffalo sculpin X — Enophrys cf. E. lucasi Leister sculpin X — Enophrys sp. (additional) Sculpin X — Hemilepidotus sp. Irish lord X X Hemitripterus cf. H. bolini Bigmouth sculpin X — Leptocottus cf. L. armatus Pacific Staghorn sculpin X — Malacocottus sp. Sculpin X — Myoxocephalus cf. M. jaok Plain sculpin X — Myoxocephalus cf. M. polyacanthocephalus Great sculpin X — Myoxocephalus cf. M. verrucosus Warty sculpin X — Oligocottus cf. O. maculosus Tidepool sculpin X — cf. Scorpaenichthys marmoratus Cabezon X — Family Agonidae Podothecus cf. P. acipenserinus Sturgeon poacher X — Family Cyclopteridae Aptocyclus cf. A. ventricosus Smooth lumpsucker X — Order Perciformes Family Bathymasteridae cf. Ronquilus jordani Northern ronquil X —

Late Wisconsin History of Prince of Wales Island 33 Table 2.4. Preliminary List of Taxa Recovered from Caves of Prince of Wales Island, Alaska (continued) Currently Living on Abundant in Taxon Common Name Prince of Wales Island1 Cave Faunas2 Family Stichaeidae Anoplarchus cf. A. purpurescens High cockscomb X — Chirolophis sp. Warbonnet X — Lumpenus cf. L. maculatus Daubed shanny X — Lumpenus cf. L. sagitta Snake prickleback X — Xiphister cf. X. atropurpureus Black prickleback X — Xiphister cf. X. mucosus Rock prickleback X — Family Pholidae Gunnels — — Apodichthys cf. A. flavidus Penpoint gunnel X — Pholis cf. P. laeta Crescent gunnel X — Family Anarhichadidae Anarrhichthys ocellatus Wolf-eel X — Family Trichodontidae Trichodon trichodon Pacific sandfish X — Family Ammodytidae Ammodytes hexapterus Pacific sand lance X — Order Pleuronectiformes Family Pleuronectidae Atheresthes cf. A. stomias Arrowtooth flounder X — cf. Hippoglossus stenolepis Pacific halibut X — Microstomus cf. M. pacificus Dover sole X — Platichthys stellatus Starry flounder X — Pleuronectes asper Yellowfin sole X — Pleuronectes cf. P. biliniata Rock sole X — Pleuronectes cf. P. vetulus English sole X — Class Aves Order Gaviiformes Family Gaviidae Gavia cf. G. pacifica Pacific loon X — Gavia cf. G. immer Common loon X — Order Pelicaniformes Family Phalacrocoracidae Phalacrocorax cf. P. auritus Double-crested cormorant X X Phalacrocorax cf. P. pelagicus Pelagic cormorant X X Order Anseriformes Family Anatidae Chen caerulescens Snow goose X — Branta canadensis Canada goose X — Branta canadensis minima3 Brant X X Anas cf. A. platyrhynchos Mallard X — Somateria mollissima Common eider X X Clangula hyemalis Oldsquaw X X Melanitta perspicillata Surf scoter X X Melanitta fusca White-winged scoter X — Bucephala cf. B. clangula Common goldeneye X — Bucephala albeola Bufflehead X — Order Falconiformes Family Accipitridae Haliaeetus leucocephalus Bald eagle X — Order Galliformes Family Phasianidae Grouse, Ptarmigan X — Order Charadriiformes Family Scolopacidae Sandpipers X —

34 TIMOTHY H. HEATON AND FREDERICK GRADY Table 2.4. Preliminary List of Taxa Recovered from Caves of Prince of Wales Island, Alaska (continued) Currently Living on Abundant in Taxon Common Name Prince of Wales Island1 Cave Faunas2 Family Laridae Larus philadelphia Bonaparte’s gull X — Larus cf. L. canus Mew gull X — Larus cf. L. glaucesens Glaucous-winged gull X — Family Alcidae Uria aalge Common murre X X Cepphus columba Pigeon guillemot X — Brachyramphus marmoratus Marbled murrelet X — Cyclorrhynchus psittacula Parakeet auklet X X Cerorhinca monocerata Rhinoceros auklet X — cf. Ptychoramphus aleuticus Cassin’s auklet X — cf. Aethia pusilla Least auklet — — Fratercula cirrhata Tufted puffin X X Fratercula sp. (large) Puffin — X Order Passeriformes Perching birds X — Class Mammalia Order Insectivora Family Soricidae Sorex cf. S. monticolus Dusky shrew X — Order Chiroptera Family Vespertilionidae Myotis spp. Myotis (small bat) X — Order Primates Family Hominidae Homo sapiens4 Human X — Order Rodentia Family Sciuridae Marmota caligata Hoary marmot — X Glaucomys sabrinus Northern flying squirrel X — Family Castoridae Castor canadensis Beaver X — Family Muridae Peromyscus cf. P. keeni Keen’s mouse X — Clethrionomys sp.5 Red-backed vole — — Phenacomys cf. P. intermedius Heather vole — X Microtus cf. M. oeconomus Tundra vole — — Microtus longicaudus Long-tailed vole X X Lemmus sibiricus Brown lemming — X Synaptomys cf. S. borealis5 Northern bog lemming — — Family Erethizontidae Erethizon dorsatum5 Porcupine — — Order Cetacea6 Great whale X — Order Carnivora Family Canidae Canis familiaris Domestic dog I — Alopex lagopus Arctic fox — X Vulpes vulpes Red fox — — Family Ursidae Ursus americanus Black bear X X Ursus arctos Brown bear — X Family Mustelidae Martes americana Marten I — Mustela erminea Ermine X —

Late Wisconsin History of Prince of Wales Island 35 Table 2.4. Preliminary List of Taxa Recovered from Caves of Prince of Wales Island, Alaska (continued) Currently Living on Abundant in Taxon Common Name Prince of Wales Island1 Cave Faunas2 Mustela vison6 Mink X — cf. Gulo gulo Wolverine Lontra canadensis River otter X X Family Otariidae Eumetopias jubatus Steller’s sea lion X — Family Phocidae Phoca vitulina Harbor seal X — Phoca hispida Ringed seal Order Artiodactyla Family Cervidae Odocoileus hemionus Mule deer X X Rangifer tarandus Caribou Family Bovidae cf. Saiga tatarica Saiga — — 1Taxa living on (or around) Prince of Wales Island today (I ϭ Introduced). 2Twenty or more specimens identified from cave faunas. 3A small subspecies of Branta canadensis. 4For discussion of the archaeological record, see Dixon (1999) and Dixon et al. (1997). 5Recovered from caves on the Alaskan mainland southeast of Wrangell (Heaton 2001b, 2001c). 6Recovered from a sea cave on Noyes Island west of Prince of Wales Island.

Fish samples have been studied from El Capitan Cave and On Your Knees Cave. Radiocarbon dates from the sealed den of El Capitan Cave were run on surface and buried fish remains and yielded early Holocene ages (Table 2.2). The closing of the cave entrance may have blocked entry after about 5,000 years ago. This den site is currently less than 400 m from the ocean and was probably used frequently by otters when it was available. On Your Knees Cave is about 1 km from the ocean, which is about the limit to which otters will travel for denning, even during the breeding season in Southeast Alaska (Woolington 1984). Use of this site by otters has probably been infrequent, but a radiocarbon age of less than 2,000 years on an otter skull (Table 2.2) and the recovery of a nearly complete modern skeleton on the surface of the cave floor indicate that Lontra canadensis has used this site in very recent times. No dates have been obtained from the fish bone itself, but the great bulk of it is at the surface and is probably Holocene. The deeper inorganic sediments of On Your Knees Cave contain some fish bone, but it has not yet been ade- quately studied. The presence and abundance of fish species from the caves reflect the fish faunas inhabiting nearby coastal areas, and here the two cave assemblages differ markedly. The coast near On Your Knees Cave is steep, exposed, and rocky with many small tide pools. The fish fauna from the cave is dominated by Irish lords, rockfish, and a diverse suite of other species that thrive in such habitats. El Capitan Cave, by contrast, is near the shallowest and quietest part of the El Capitan Passage, where incom- ing streams create brackish water and where mud flats are exposed at low tide. The dominant fishes from this cave are flatfish (Family Pleuronec- tidae) and sculpins of the genus Myoxocephalus, which prefer such con- ditions. Several sculpins are also present that prefer fresh to brackish wa-

36 TIMOTHY H. HEATON AND FREDERICK GRADY ter: Cottus asper (prickly sculpin) and Cottus aleuticus (coastrange sculpin). Irish lords, greenlings, and pricklebacks are much less common than at On Your Knees Cave (Heaton and Grady 1999). Several well-preserved fish specimens remain unidentified because of a shortage of comparative material. All comparative specimens used in this study were modern, so it is possible that extinct or extirpated species are present but have not been recognized.

Birds About half of the larger bones recovered from On Your Knees Cave are of birds, whereas the extensive excavations at El Capitan and Bumper caves have yielded only a few bird bones. Nearly all the bones are of aquatic species, particularly alcids, diving ducks, geese, and cormorants (Table 2.4). These bones are found at all depths in the sediment, and their association with Marmota suggests an age predating the last glacial maximum for many of them. Bones of some species have also been found in organic surface sediments and are probably postglacial. With the ex- ception of Aethia pusilla (least auklet), a northern species, and what ap- pears to be a larger species of Fratercula (puffin) than any living form, all of these bird taxa still inhabit the region of Prince of Wales Island. Many of the bird bones have distinct bite marks from mammalian carnivores; thus predation is clearly their source. The most likely predators are otter and fox. Lontra canadensis occasionally kills or scavenges birds in coastal Southeast Alaska, particularly marine birds like the ones in the cave, but these generally make up only a small percentage of its diet compared to fish, and the bones or fragments have to be small enough to pass through the digestive track (Home 1982; Larsen 1983, 1984; Wool- ington 1984). The abundance and good preservation of bird bones in On Your Knees Cave and the paucity of fish remains in the deeper deposits suggest that otters were not the primary predator in this case. A partial skeleton of Alopex lagopus dating to 11,275yr b.p. (Table 2.2) was found at the contact between organic and inorganic sediments and was closely associated with carnivore-chewed bird and ungulate bones. Fragmentary remains matching A. lagopus have also been found throughout the deeper sediments where bird bones are common. A. lagopus is known to prey extensively on sea birds in the summertime and cache their remains (Chesemore 1968, 1969, 1975; Fay and Cade 1959; Fay and Stephenson 1989), so this species is the most likely predator responsible for the bird component of the deposit (Heaton and Grady 1999). The paucity of bird remains at El Capitan Cave, a south-facing den site even closer to the ocean than On Your Knees Cave, is surprising. One probable explanation is that the shallow El Capitan Passage was drained of seawater and/or filled with glacial ice during much of the late Pleistocene when On Your Knees Cave was accumulating bird bones, and therefore it was not in its modern coastal setting. No Alopex remains were found in El Capitan Cave even though the site was available for at least 1,000 years of the time that this species lived on the island (compare ages in Table 2.2). Vulpes vulpes and Lontra canadensis are represented and may even have used the den during a higher-than-modern stand of sea level that peaked about 9,000 years ago (see Baichtal et al. 1997), but

Late Wisconsin History of Prince of Wales Island 37 if so, neither carnivore accumulated many birds. This further reinforces the connection between sea birds and A. lagopus at On Your Knees Cave.

Rodents and Other Small Mammals Rodents have had significant turnover on Prince of Wales Island and have been useful as index fossils in On Your Knees Cave for distinguishing sediments of different ages. The only modern rodents native to the island are Glaucomys sabrinus (northern flying squirrel), Castor canadensis, Per- omyscus keeni, and Microtus longicaudus (MacDonald and Cook 1996, 1999), and all of these have been found in postglacial cave deposits (though only M. longicaudus is common). Several teeth that match Mi- crotus oeconomus (tundra vole) have also been found. This species was a late invader in North America but colonized quickly as glaciers retreated, and it is now restricted to the northernmost islands in the Alexander Archipelago (Lance and Cook 1998). The older, inorganic sediments of On Your Knees Cave contain many bones and teeth of Marmota caligata, Phenacomys cf. P. intermedius (heather vole), and Lemmus sibiricus (brown lemming), none of which have ever been found in postglacial deposits of the Alexander Archipelago. (The Phenacomys remains match P. intermedius but are larger on aver- age.) Today M. caligata is restricted to the mainland of Southeast Alaska, and the closest populations of P. intermedius and L. sibiricus are in the mountains of British Columbia (Hall 1981; MacDonald and Cook 1996, 1999). Of these, only fossil remains of M. caligata have been radiocarbon dated (Table 2.2), and all predate the last glacial maximum (Heaton and Grady 1997, 2000; Heaton et al. 1996). The two microtine taxa appear to have the same time range as Marmota based on association. The turnover in rodent taxa can be interpreted both in terms of habitat preferences and colonization/extinction events. M. caligata, P. in- termedius, and L. sibiricus prefer open habitat and would not be expected to occur in the rainforest that covers all but the mountain peaks of Prince of Wales Island today. Yet they appear to have thrived in the middle Wisconsin interstadial when trees were probably more sparse. M. longi- caudus, by contrast, thrives in the dense modern rainforest. Unfortunately a simple turnover resulting from forest expansion is precluded by the timing of the extirpations. M. caligata, P. intermedius, and L. sibiricus should have thrived in the early postglacial interval prior to extensive forest development, as did large mammals with similar habitat preferences (Ursus arctos, Alopex lagopus, Rangifer tarandus, etc.). It appears instead that the severity of the last glacial maximum drove these rodents to ex- tinction on the islands and that they never succeeded at recolonization, even when favorable habitats returned. Island colonization must always have been difficult for small terrestrial mammals, as illustrated by the complete lack of lagomorphs both in the fossil and modern island faunas. Ochotona collaris (collared pika) and Lepus americanus (snowshoe hare) occur on the Alaskan mainland and could surely have thrived on the islands at the beginning and end of the last glacial maximum had they succeeded at colonization. Conroy et al. (1999) found that ocean barriers were the main factor in determining modern species richness on the islands of the Alexander Archipelago.

38 TIMOTHY H. HEATON AND FREDERICK GRADY Bones of shrews, bats, and other rodents (in addition to those dis- cussed above) are rare in all of the caves we have excavated, but extensive screen washing of sediments has produced some remains (Table 2.2). We set traps in El Capitan Cave during our 1992 excavation and at the On Your Knees Cave entrance in 1998 and captured only Peromyscus keeni. Bats also live in El Capitan Cave and many other caves. Yet both of these are uncommon fossil elements in all the sites sampled. Since the most abundant rodents in the cave deposits, the microtines, are not generally cave dwellers, it is likely that the vast majority of fossil micromammals were brought into the caves as prey items. Ables (1975) reported that foxes prefer microtines over Peromyscus, possibly due to ease of capture. Foxes (Alopex lagopus and Vulpes vulpes) and various mustelids (Mustela er- minea [ermine], M. vison [mink], Gulo gulo, Lontra canadensis, etc.) are the most likely carnivores responsible.

Carnivores and Pinnipeds Excluding bats, about half of the modern terrestrial mammal species of Prince of Wales Island are carnivores (MacDonald and Cook 1996, 1999). Likewise, carnivores make up about half of the extirpated mammalian species found in our excavations (Table 2.4). The reason for this seeming overabundance is the wealth of marine food that many of these carnivores rely on. Some species have very diverse diets, making the link between carnivores and their prey complex. Stable isotope studies have helped to determine the dietary habits of some of the carnivores on the island (Fig- ure 2.6; Table 2.3). Because the bulk of our excavation sites are carnivore dens used by multiple species, it is for these mammals that we have been able to make the most complete life history reconstructions.

Ursids Bear fossils are what first brought our attention to the caves of Southeast Alaska, and they have continued to play a major role in our research (Heaton and Grady 1992, 1993, 1997; Heaton et al. 1996). Currently Ursus americanus is the only bear living on Prince of Wales Island and other islands of the southern Alexander Archipelago, while Ursus arctos is the only bear inhabiting the northern islands. Klein (1965) attributed this modern distribution to timing of postglacial colonization, with U. americanus moving northward from the midcontinental states and U. arc- tos moving southward from eastern Beringia, and with the assumption that each island could only support the one species of bear that first arrived there. Contrary to this theory, we found that U. americanus and U. arctos coexisted on Prince of Wales Island (Coronation and Dall is- lands) from the latest Pleistocene until at least 7200 yr b.p. (Table 2.2). What finally drove U. arctos to extinction on the southern islands is un- clear, but a likely factor is the dense forest habitat that developed during the Holocene, covering all but the highest mountain peaks. More open habitat, preferred by U. arctos, is still available on the northern islands of the archipelago and on the nearby mainland where U. arctos still thrives (Banfield 1974; MacDonald and Cook 1996, 1999). The large number of bear bones dated to the latest Pleistocene and earliest Holocene, compared to the very small number dated to the later

Late Wisconsin History of Prince of Wales Island 39 Holocene, deserves attention. With the exception of the El Capitan Cave den, which became sealed off by rocks and tree fall during the Holocene, all the den sites are still open and available for use. The paucity of late Holocene bones in such caves might suggest that bears lost their prefer- ence for caves as den sites once the forest developed. But natural trap caves show the same bias toward late Pleistocene bear remains. Brown bears prefer open habitat, and black bears have more plant food available in early successional stages of forest development than they do in climax coniferous forests. Therefore, we speculate that bears had a much higher population density in the early postglacial period before conifers came to dominate the island landscape. Remains of U. arctos have been found in On Your Knees Cave dating back to at least 35,000 yr b.p., and, as in postglacial times, this species coexisted with U. americanus (Heaton 1995a; Heaton et al. 1996; Table 2.2). Whether either of these bears survived the last glacial maximum in the archipelago or recolonized it afterward has not been documented by the fossil record, but the former theory is a valid possibility. A genetic study on U. arctos of Admiralty, Baranof, and Chichagof islands (Figure 2.1) concluded that the population there is so distinct from all other populations of that species in the world that it may have been isolated for as long as 700,000 years (Talbot and Shields 1996). The fossils suggest that the most likely location for this isolation is the Alexander Archipelago itself (Heaton et al. 1996). U. arctos fossils from El Capitan, Bumper, and On Your Knees caves have been tested unsuccessfully for the presence of ancient DNA (Michael Kohn and Alan Cooper, pers. com.). DNA was successfully extracted from one U. arctos fossil from Blowing in the Wind Cave, dated at 9995yr b.p. (Table 2.2), and it matches the Admiralty/ Baranof/Chichagof Island lineage (Barnes et al. 2002). This strongly suggests that U. arctos survived the last glacial maximum in Southeast Alaska. Bears tend to keep their dens cleaner than do smaller carnivores such as otters, and therefore less information is available about their prehistoric diets. The oldest U. arctos skeleton from El Capitan Cave has large tooth punctures on nearly every bone, which were clearly made by the canines of other bears; which bear species was responsible and whether the chew- ing occurred soon or long after death is unknown. The same applies to a Phoca hispida humerus from On Your Knees Cave. Other than these cases, however, it is unknown whether any of the smaller fauna from the caves was killed or scavenged by bears. Much of the bear diet is vegetable matter that would not preserve well. Stable isotope analysis on both modern and fossil U. americanus from Prince of Wales Island indicates that this species has a virtually exclusive terrestrial diet in spite of the fact that these bears are occasionally seen catching salmon (Heaton 1995b; Champe and Heaton 1996; Figure 2.6; Table 2.3). Stable isotope values on fossil U. arctos indicate a roughly equal diet of terrestrial food (pre- sumably plant matter) and marine food (presumably salmon).

Canids The second extirpated species found in the cave faunas was Vulpes vulpes, represented by a dentary and an upper canine from El Capitan Cave

40 TIMOTHY H. HEATON AND FREDERICK GRADY dating to 10,050 yr b.p. (Table 2.2). This documented a replacement within the Canidae because Canis lupus is the only wild canid living in the Alexander Archipelago today. Not a single fossil of C. lupus has yet been found in our cave faunas, so it may be a recent arrival. V. vulpes dislikes uniform habitats and may have disappeared when the islands be- came heavily forested early in the Holocene (Ables 1975). When parts of a fox skeleton were later found in On Your Knees Cave, dating to 11,275yr b.p., we assumed that this also represented V. vulpes (Heaton and Grady 1997). But additional material and analysis have led us to conclude that the primary fox in the On Your Knees Cave fauna is actually Alopex lagopus. Alopex has a shorter jaw, more closely spaced teeth, and shorter canines and limbs than V. vulpes (Stains 1975). This is an important identification because On Your Knees Cave has an unusual fauna that is consistent with the involvement of A. lagopus. Arctic fox remains have now been dated to the last glacial maximum and even beyond the range of radiocarbon dating (Table 2.2). Alopex usually dens in burrows on open tundra but is also known to use rock piles along the bases of south-facing cliffs, similar to the entrance of On Your Knees Cave. It frequently caches food in its dens and can accumulate sufficient organic matter to promote the growth of surround- ing vegetation (Chesemore 1969, 1975). A. lagopus has a diverse diet but is especially adept at killing lemmings, sea birds, and ringed seal pups (Banfield 1974; Chesemore 1968, 1975; Dalerum and Angerbjo¨rn 2000; Fay and Stephenson 1989; Smith 1976, 1980). This species makes exten- sive travels on sea ice and often follows Ursus maritimus (polar bear), the other land-based predator of Phoca hispida, to obtain carrion. The use of On Your Knees Cave by A. lagopus is the best explanation for the abun- dance of sea birds at a distance of 1 km from the ocean, for the many rodent and pinniped remains found in the cave, and for the presence of carnivore-gnawed ungulate bones. It could also be responsible for several deep burrows at the boundary of inorganic and organic sediments within the cave, several of which contained extensively chewed bones. Although bears must have dominated the site on some occasions, Alopex may have excluded otters from the cave until the Holocene, when fish remains began to accumulate in large quantities. The closest modern populations of A. lagopus to Prince of Wales Island are in the Northwest Territories (1,000 km northeast) and western Alaska (1,200 km northwest). But the affinity of this species for sea ice suggests that it had a more southerly range during colder glacial episodes. The On Your Knees Cave skeleton postdates the last glacial maximum by 2,000 years or more, but A. lagopus could easily have survived after the ice melted as it did into modern times (in great numbers) on Bering Island (Ford 1966). The warming climate, development of dense forest, and competition with V. vulpes are logical factors in its eventual extir- pation. Attempts to reintroduce Alopex to the islands of the Alexander Archipelago were made by hopeful trappers in the early 1900s, but none were successful (MacDonald and Cook 1996, 1999). Table 2.2 provides radiocarbon dates on A. lagopus and V. vulpes, suggesting that they coexisted for more than 11,000 years. It seems par- adoxical to us that these two species could have occupied Prince of

Late Wisconsin History of Prince of Wales Island 41 Wales Island and even used the same cave during the last glacial maxi- mum and into the early postglacial interval when all island rodents had been extirpated. Modern V. vulpes dominates and even preys on A. la- gopus whenever their ranges overlap (Chesemore 1975; Schamel and Tracy 1986). We have considered the possibility that all the fossil remains actually represent one species or the other, and we will continue to do so with additional collection and analysis. But the fox material from On Your Knees Cave covers the full morphological spectrum of both species with respect to every distinguishing characteristic (with Ͼ90 percent of remains best matching Alopex). An oddity in our collection are several bones and a molar of Canis familiaris (domestic dog) found in Kushtaka Cave. Their position on the floor not far from the cave entrance suggests a recent age. (Early Holo- cene Ursus americanus remains from this cave were found farther inside the same passage and beyond a tight crawlway.) Kushtaka Cave is located close to a small bay that receives frequent visitation by boat, so the pres- ence of a domestic animal is not surprising.

Mustelids Lontra canadensis is currently the most extensive user of coastal cave dens and appears to have been so throughout the Holocene. Fresh signs are common in caves near the coast and become less frequent inland. Ex- tensive studies have been done on the diet and habits of L. canadensis in Southeast Alaska, including Prince of Wales Island (Home 1982; Larsen 1983, 1984; Woolington 1984). Although this species is an opportunistic feeder, in this region the bulk of its diet consists of coastal fishes with minor elements including birds, rodents, and marine invertebrates. The thick beds of fish bone from El Capitan, Kushtaka, and On Your Knees caves have the same mix of these elements as reported in modern fecal studies. Stable isotope analysis on L. canadensis indicates a fully marine diet (Figure 2.6; Table 2.3). Also common in El Capitan and On Your Knees caves are fragmentary remains of juvenile otters that apparently died before leaving the den. Only three specimens of L. canadensis have been radiocarbon dated, and all have Holocene ages (Table 2.2). The three dated samples of fish bone from El Capitan Cave are also believed to be otter related and date to the early Holocene. However, remains of L. canadensis and fish bones resembling otter scat have been found in deep sediments of On Your Knees Cave in association with Marmota and other species of the middle Wisconsin interstadial. Thus, this species has a long history in the Alex- ander Archipelago and may have even survived the last glacial maximum there. Modern river otters from Prince of Wales and surrounding islands comprise a morphologically distinct subspecies, L. canadensis mira (van Zyll de Jong 1972; Fagen 1986), which suggests the possibility of long- term habitation in the archipelago. A single molar fragment from El Capitan Cave appears to match only Gulo gulo, making this another extirpated carnivore from the latest Pleistocene or early Holocene of Prince of Wales Island. This species occurs throughout most of Alaska and Canada and as a rare element on some islands, including those immediately north of Prince of Wales Island

42 TIMOTHY H. HEATON AND FREDERICK GRADY (MacDonald and Cook 1996, 1999). Being a tundra and alpine species, G. gulo probably had a greater range prior to extensive forest develop- ment. Because this species always has a low population density (van Zyll de Jong 1975), it probably played little role in the accumulation of prey species in the caves. Mustela erminea and M. vison are common mustelids living on Prince of Wales Island, including the proximity of several excavated caves. Remains of M. erminea have been found in El Capitan and On Your Knees caves, but most appear to be late Holocene. The preservation sug- gests that these animals entered the caves on their own rather than as prey items. Isolated teeth matching M. vison have also been found in On Your Knees Cave both in surface and subsurface sediments. Some of these remains more closely match Martes americana (marten); these two similar-sized mustelids can be difficult to distinguish. M. americana is a forest dweller that is not native to Prince of Wales Island but was suc- cessfully introduced in 1934 (MacDonald and Cook 1996, 1999). It is native to other parts of Southeast Alaska, however. Without positive iden- tifications or radiocarbon dates, it is difficult to draw conclusions from these mustelid fossils.

Pinnipeds Bones and teeth of several pinnipeds have been found in On Your Knees Cave. Phoca hispida is by far the most abundant species, but Phoca vi- tulina (harbor seal), Eumetopias jubatus (Steller’s sea lion), and possibly others are also represented. All appear scavenged. The first P. hispida bone submitted was reported as 17,565 yr b.p. (Heaton 1996a; Heaton et al. 1996), but we later learned that the lab had not properly prepared the sample. Additional dates on the same bone by two labs were reported as 19,060 and 20,660 yr b.p., and another bone believed to be from the same individual was dated at 20,060 yr b.p. Other specimens have been dated from 13,690 to 24,150 yr b.p. (Heaton and Grady 1997; Table 2.2), which is approximately the period of the last glacial maximum. P. vitulina and E. jubatus are found throughout the age range of the On Your Knees Cave deposit including the last glacial maximum (Table 2.2), and they are both common around Prince of Wales Island today (MacDonald and Cook 1999). P. hispida is an important find because it currently inhabits Arctic waters and breeds on land-fast sea ice, and it has been considered a pa- leoclimatic indicator of extensive sea ice by many researchers (Banfield 1974; Harington 1977, 1978; Harington and Sergeant 1972; Scheffer 1967). We have submitted a large number of P. hispida bones for dating in order to assess the temporal range of sea ice during the last glacial maximum (Table 2.2). The two main land-based predators of this seal are Ursus maritimus and Alopex lagopus. Both A. lagopus and Vulpes vulpes also scavenge carcasses of adult seals (Andriashek et al. 1985). One hu- merus of P. hispida from On Your Knees Cave has distinct bite marks that match the size of Ursus canines, but which species of Ursus might be responsible, and whether a bear actually brought the remains to the cave or not, is unknown. Some seal remains also appear scavenged by foxes or other small carnivores.

Late Wisconsin History of Prince of Wales Island 43 Artiodactyls The only ungulate native to Prince of Wales Island and most other islands of the Alexander Archipelago is the Sitka black-tailed deer, a small sub- species of Odocoileus hemionus restricted to Southeast Alaska. This arti- odactyl thrives in the dense rainforest and is the most common mammal seen along roadways. Fragmentary remains have been found in On Your Knees Cave, and more complete material has been recovered from nat- ural trap caves on several islands. The oldest radiocarbon dates are early (but not earliest) Holocene (Table 2.2). The most interesting specimen of O. hemionus recovered is a nearly complete skeleton from Tlacatzinacantli Cave dating to 8000 yr b.p., mak- ing it the oldest known deer from Prince of Wales Island. Part of the passage through which this animal apparently fell into the cave is now plugged with rock debris. The skeleton matches perfectly with a large male Sitka black-tail deer, but the antlers are very unusual (Figure 2.5). They have large protuberances around the basal 10-cm and well- developed basal posterior tines. One antler is broken off 12 cm above the base (apparently while the animal was living), but the other is a gently curved structure 40 cm long, with a single branch near the tip. We found nothing similar to this in the Smithsonian Institution’s collection of about 600 Odocoileus skulls with antlers. (Several were found with basal pro- tuberances, but they were all on antlers with many branches.) Deer can develop abnormal antlers for a variety of reasons (Goss 1983), but the antlers generally fall into a small number of basic patterns, none of which are consistent with the Tlacatzinacantli Cave deer. Modern examples of antlers with basal posterior tines have been found on and near Prince of Wales Island (J. F. Baichtal, pers. com.). This suggests that this animal may not be abnormal but rather part of a formerly isolated population with an unusual morphological characteristic. The other cervid found in the cave deposits is Rangifer tarandus.A small population of this species survived into modern times on the Queen Charlotte Islands (Banfield 1961, 1962; Foster 1965), and a metapodial fragment was found in an early Holocene archaeological site on Heceta Island (Ackerman 1992). So the former presence of this species on Prince of Wales Island is not surprising. Specimens have been dated from three caves, and they demonstrate that this cervid lived on the island both before and after the last glacial maximum (Table 2.2). The basal half of a caribou antler is the largest single fossil recovered from On Your Knees Cave. The antler looks naturally shed and has been heavily gnawed by a fox-size carnivore. Alopex lagopus is known to scavenge caribou and even attack weak fawns (Chesemore 1975). Based on these preliminary results, R. tarandus may have been the only cervid living on Prince of Wales Island through the late Pleistocene, and it may have even survived the last glacial maximum on the island. Its postglacial replacement by O. hemionus would have been a natural consequence of the shift from tundra to dense forest, as it was on the Queen Charlotte Islands. The most enigmatic fossils from On Your Knees Cave are the tip of a horn core dating to 32,000 yr b.p. and bovid lower molars, which best match Saiga tatarica. The straightness and rounded cross section of the

44 TIMOTHY H. HEATON AND FREDERICK GRADY horn core does not make a good match with Oreamnos americanus (mountain goat) or Ovis dalli (Dall’s sheep), the only two bovids living anywhere in Southeast Alaska today (MacDonald and Cook 1996, 1999). S. tatarica is now restricted to Central Asia, but during the Pleistocene it ranged from England to central Alaska (Guthrie 1990; Harington 1981; Sokolov 1974). The On Your Knees Cave specimens predate the last glacial maximum (Table 2.2), and the stable isotope value indicates a terrestrial diet (Table 2.3). Despite extensive searching, no additional ma- terial of this small artiodactyl has yet been found. If the identification is correct, this species, along with Ursus arctos, suggests an early coastal connection with Asia that apparently did not extend south of the conti- nental glaciers.

Conclusions Our fossil excavations on Prince of Wales Island have demonstrated that the faunal history of Southeast Alaska is far more complex than previously thought. Rather than a simple postglacial colonization of a formerly in- hospitable wasteland, we see a complex interaction of faunas—arctic and temperate, coastal and inland, Asian and North American—all interacting through a period of radical climatic change. Understanding the arrivals and extinctions, their timing, and the reasons behind them has been the goal of our research. We have recovered and identified extensive bone material belonging to three vertebrate classes. Fish and birds have a greater diversity in the fauna than mammals but represent far fewer extirpated taxa, perhaps be- cause of their greater mobility and larger ranges. Only about half of the mammalian species recovered from the caves inhabit Prince of Wales Island today (Table 2.4). The extirpated species thrive elsewhere, but their ranges have shifted to higher latitudes and/or elevations. The cave faunas of Prince of Wales Island allow us to evaluate the biotic changes that occurred on the coastal islands as a result of two main climatic events: the last glacial maximum and the transition from the glacial maximum to a coastal rainforest habitat. Although the fossil record extends long before either of these events, chronologic resolution is lack- ing, and we use the middle Wisconsin data only as a starting point for evaluating the effects of the last glacial maximum. Middle Wisconsin conditions are not well documented for the region, but sea surface tem- perature data indicate that conditions were cooler than today (Blaise et al. 1990; Fladmark 1983). A comparison of the faunas before, during, and immediately after the last glacial maximum can be used to evaluate the effects of that event. Figure 2.7 provides a timeline of documented and probable mammalian faunal composition for Prince of Wales Island dur- ing the time periods in question. The mammals of the last glacial maximum can be divided into those that benefited from the expansion of glaciers and sea ice (the Arctic fauna) and those that were threatened but attempted to survive the harsh con- ditions (the Refugium fauna). The Arctic fauna is best documented by the presence of Phoca hispida, a seal that breeds on land-fast sea ice, and

Late Wisconsin History of Prince of Wales Island 45 Figure 2.7. Time line of selected vertebrate taxa on Prince of Wales Island, Alaska. Stars indicate radiocarbon dates, and horizontal lines indicate our inter- pretations of species presence based on inferences and associations. Dashed lines are shown for mammalian species that may have survived the last glacial maxi- mum on coastal refugia or may have recolonized the island in early postglacial times. Question marks are shown for species that are poorly represented or absent in the cave faunas. The chart begins at 40,000 yr b.p. because most radiocarbon dates beyond that time are limitless dates (Table 2.2). For a discussion of the human remains and artifacts, see Dixon (1999) and Dixon et al. (1997).

Alopex lagopus, a fox that is especially adapted for life on sea ice and coastal tundra. Ursus maritimus probably also extended its range south- ward in concert with P. hispida, though this has not been documented. P. hispida and other pinnipeds have been dated to the last glacial maxi- mum, as have foxes (Table 2.2; Figure 2.7). We believe that A. lagopus was present for a long period of time and played a key role in accumu- lating the On Your Knees Cave fauna. P. hispida was extirpated when the southern limit of sea ice retreated northward, while A. lagopus managed to remain on Prince of Wales Island for at least 2,000 years after the end of the last glacial maximum. The notion of a Refugium fauna that survived the last glacial maxi- mum in the Alexander Archipelago has long been contested (see review in Heaton et al. 1996). Our work strongly suggests the possibility of such a fauna but falls short of unequivocally documenting it. Only direct ra- diocarbon dates or genetic linkages on fossil bone can distinguish between a fauna that survived in a refugium and one that was reintroduced fol- lowing extirpation. What we do know is that some taxa were permanently extirpated by the last glacial maximum (Marmota, Phenacomys, Lemmus,

46 TIMOTHY H. HEATON AND FREDERICK GRADY and Saiga), whereas other taxa were present both before and soon after- ward (Ursus americanus, Ursus arctos, Lontra, and Rangifer; Figure 2.7). In the case of Ursus arctos, genetic studies of modern and fossil animals strongly support the refugium theory (Talbot and Shields 1996; Heaton et al. 1996; Barnes et al. 2002). Ursus americanus and Rangifer tarandus, being primarily herbivores, would have required adequate terrestrial plant food to survive on a refugium. What is clear from our work at On Your Knees Cave is that the Alexander Archipelago, with the relatively warm Pacific waters and availability of marine food, was a haven from the fore- boding ice sheets to the east and that sufficient land was exposed during the last glacial maximum to support terrestrial mammals. The transition from the glacial maximum to the modern temperate rainforest occurred in several stages with some faunal differences (Figure 2.7). Warmer temperatures and retreating glaciers left a climate that was probably similar to the one preceding the last glacial maximum. U. arctos and U. americanus were both common and widespread, and R. tarandus was probably the only ungulate present on Prince of Wales Is- land. Alopex lagopus remained as a holdout from the Arctic fauna. It appears that many potentially successful species did not colonize the is- lands simply because of barriers (Lepus americanus, Ochotona, Marmota, Clethrionomys, Phenacomys, Lemmus, Synaptomys). However, the early postglacial fauna was gradually supplemented by a host of new arrivals, some of which survived to the present day (Canis lupus, Microtus longi- caudus, Odocoileus hemionus, etc.) and some of which did not (Gulo gulo, Microtus oeconomus). These species probably arrived from the north and south through the coastal corridor between retreating glaciers and the ocean. The early postglacial period of open, ice-free habitats was short-lived, and soon Prince of Wales Island provided favorable habitat for forest dwellers. It appears that Odocoileus hemionus replaced Rangifer tarandus as the only artiodactyl; Canis lupus replaced Alopex lagopus and Vulpes vulpes among the canids; and Ursus arctos, Gulo gulo, and Microtus oec- onomus disappeared (Figure 2.7). Unsuccessful human introductions of Lepus americanus, Marmota caligata, Tamiasciurus hudsonicus, Ondatra zibethicus, and Alopex lagopus (MacDonald and Cook 1996, 1999) sug- gest that Prince of Wales Island is close to equilibrium with its present low mammal diversity (only Martes americana was introduced success- fully outside of human settlements). Apparently, the uniformity of the forest and coastal environments favors large populations of just a few well- adapted species. Species now extirpated from Prince of Wales Island but found in the cave deposits fall into three distinct categories in terms of their modern distributions and associations: (1) Arctic fauna (Phoca hispida and Alopex lagopus) now occupies extreme northern latitudes of Alaska and Canada; (2) alpine species (Marmota caligata, Phenacomys intermedius, Lemmus sibiricus, Vulpes vulpes, and Rangifer tarandus) occupy higher elevations in the Cordillera of British Columbia such that the western extent of their ranges parallel the Southeast Alaskan coast; and (3) nearby species (Ursus arctos, Gulo gulo, and Microtus oeconomus) have reduced northern distributions within the Alexander Archipelago, inhabiting islands with

Late Wisconsin History of Prince of Wales Island 47 less forest cover than Prince of Wales Island (Hall 1981; MacDonald and Cook 1996, 1999). The changes in mammal distribution documented from the cave deposits of Prince of Wales Island allow us to address questions about the ability of mammals to adjust to rapidly changing climatic conditions. We see no evidence that substantial species evolution took place in response to these changes, but rather species shifted their ranges to remain (where possible) in their preferred habitats. Shifting of ranges can be difficult, however, when islands are surrounded by barriers such as ocean straits and glaciers. What we find is that large mammals have had a much greater ability to cross such barriers than small mammals. Four distinct climatic periods with distinct mammalian faunas can be recognized during the time frame of our study: (1) middle Wisconsin, (2) glacial maximum, (3) early postglacial, and (4) late postglacial (Figure 2.7). The middle Wisconsin was long enough that faunal equilibrium was probably reached (i.e., species that were adapted to prevailing con- ditions had time to colonize Prince of Wales Island). The next two pe- riods, the last glacial maximum and the early postglacial (latest Pleisto- cene), were of shorter duration, and it appears that only a fraction of the potential inhabitants had time to colonize. Phoca hispida and Alopex la- gopus succeeded in reaching Prince of Wales Island, but Dicrostonyx groenlandicus, an arctic rodent normally preyed upon by A. lagopus and which surely would appear in the fossil record if it were present, did not succeed in colonizing the island even after glacial conditions extirpated its potential competitors (Phenacomys and Lemmus). Similarly, the ro- dents and lagomorphs (Marmota, Phenacomys, Lemmus, Ochotona, etc.) that would have thrived on the island during deglaciation with virtually no competition failed to colonize, probably because the barriers were too substantial. Larger mammals, such as bears and caribou, either survived the glacial maximum on the island or quickly recolonized it afterward. The lack of rodents on Prince of Wales Island from the last glacial maximum to near the end of the Pleistocene may help account for the abundance of bird bones in On Your Knees Cave. Birds, with their su- perior ability to colonize islands, may have been the main source of meat available to Alopex lagopus for thousands of years, particularly after Phoca hispida disappeared (Figure 2.7). The inability of the Arctic fauna to fully establish itself on Prince of Wales Island during the last glacial maximum, either because of inade- quate time or conditions, can be seen as a positive factor for the idea of a Refugium fauna. Another arctic animal with a modern distribution sim- ilar to Alopex and Dicrostonyx (and a greatly expanded late Pleistocene distribution) is Ovibos moschatus (Hall 1981; Kurte´n and Anderson 1980). The apparent lack of this grazer and browser on Prince of Wales Island during the last glacial maximum would have afforded a better chance for the survival of Rangifer tarandus because they share many of the same plant foods (Banfield 1974). In the case of bears, however, Ursus mariti- mus would probably not have threatened the survival of U. americanus or U. arctos, as their habitat preferences and foods are very different. The Holocene Epoch appears to have been long enough for a full equilibrium forest community to establish itself on Prince of Wales Island,

48 TIMOTHY H. HEATON AND FREDERICK GRADY but it took at least 5,000 years for this to occur. Although it is not known exactly when most of the new species arrived, it is clear that there was a long period of transition before the modern forest community stabilized. Microtus oeconomus, Vulpes vulpes, Ursus arctos, Gulo gulo, and Rangifer tarandus eventually died out, probably in early to middle Holocene times (Figure 2.7). Whether late changes in the distribution or composition of the forest were responsible or merely competition between species that shared the same resources is unknown. Undoubtedly both were important factors in various cases. While many details remain to be evaluated, our excavations in the caves of Prince of Wales Island have documented a succession of distinct mammal communities as the climate cooled then warmed across the last glacial maximum and up to the present day. The Alexander Archipelago was continuously occupied both by terrestrial and marine vertebrates over the past 50,000 years, but the species composition underwent complex changes due to habitat alteration, barriers to travel, and competition be- tween long-term inhabitants and new arrivals. The modern coastal rain- forest and its island communities of land- and sea-adapted animals is but the latest chapter in this rich history.

Acknowledgments We are indebted to the cavers of the Tongass Caves Project, particularly Kevin and Carlene Allred, David Love, Peter Smith, Stephen Lewis, and Daniel Mon- teith, for discovering, documenting, and reporting the fossil localities discussed in this chapter. They have also helped facilitate our excavations in numerous ways. Special thanks also goes to officials of Tongass National Forest, particularly James Baichtal, Terence Fifield, and Cat Woods, who have served as our liaisons. They have secured for us lodging, food, transportation (including by helicopter and boat), and funds for radiocarbon dating, and in some cases they have person- ally assisted with the excavations. E. James Dixon has provided much support through our collaborative fieldwork. Robert A. Sattler helped evaluate the bone modification by carnivores. The manuscript was greatly improved by comments from James Baichtal, Anthony Barnosky, Joseph Cook, Terence Fifield, Stephen MacDonald, Gregory McDonald, Madonna Moss, Robert Sattler, and the editors. Funding for this project has been provided by research grants from the National Geographic Society (4857-92, 5617-96, 6212-98), the National Science Founda- tion (EAR-9870343), the National Speleological Society, and the University of South Dakota.

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