Biological Monitoring at St. Paul Island, Alaska in 2011

Total Page:16

File Type:pdf, Size:1020Kb

Biological Monitoring at St. Paul Island, Alaska in 2011 AMNWR 2011/14 BIOLOGICAL MONITORING AT ST. PAUL ISLAND, ALASKA IN 2011 Gregory Thomson and Brie Drummond Key words: Aethia pusilla, Bering Sea, black-legged kittiwake, breeding biology, common murre, least auklet, Otter Island, Phalacrocorax urile, populations, Pribilof Islands, productivity, red-faced cormorant, red-legged kittiwake, Rissa brevirostris, Rissa tridactyla, St. Paul Island, thick-billed murre, Uria aalge, Uria lomvia, Walrus Island. U.S. Fish and Wildlife Service Alaska Maritime National Wildlife Refuge 95 Sterling Highway, Suite 1 Homer, AK 99603 October 2011 Cite as: Thomson, G. and B. Drummond. 2011. Biological monitoring at St. Paul Island, Alaska in 2011. U.S. Fish and Wildl. Serv. Rep., AMNWR 2011/14. Homer, Alaska. Plot 48 at High Bluffs, St. Paul Island TABLE OF CONTENTS Page INTRODUCTION ..................................................................................................................................... 1 STUDY AREA ......................................................................................................................................... 1 METHODS .............................................................................................................................................. 2 INTERESTING OBSERVATIONS ............................................................................................................ 3 ACKNOWLEDGMENTS .......................................................................................................................... 3 REFERENCES ........................................................................................................................................ 4 ISLAND MAPS ........................................................................................................................................ 7 FIGURES AND TABLES.......................................................................................................................... 9 Northern fulmar ............................................................................................................................... 10 Populations ............................................................................................................................... 10 Food habits ............................................................................................................................... 13 Red-faced cormorant ....................................................................................................................... 14 Breeding chronology ................................................................................................................. 14 Reproductive performance ........................................................................................................ 18 Populations ............................................................................................................................... 23 Chick banding ........................................................................................................................... 28 Food habits ............................................................................................................................... 34 Black-legged kittiwake ..................................................................................................................... 36 Breeding chronology ................................................................................................................. 36 Reproductive performance ........................................................................................................ 40 Chick growth ............................................................................................................................. 44 Populations ............................................................................................................................... 46 Survival ..................................................................................................................................... 50 Food habits ............................................................................................................................... 55 Red-legged kittiwake ....................................................................................................................... 59 Breeding chronology ................................................................................................................. 59 Reproductive performance ........................................................................................................ 63 Chick growth ............................................................................................................................. 67 Populations ............................................................................................................................... 68 Food habits ............................................................................................................................... 73 Common murre ............................................................................................................................... 75 Breeding chronology ................................................................................................................. 75 Reproductive performance ........................................................................................................ 79 Populations ............................................................................................................................... 83 Food habits ............................................................................................................................... 86 Thick-billed murre ............................................................................................................................ 88 Breeding chronology ................................................................................................................. 88 Reproductive performance ........................................................................................................ 92 Populations ............................................................................................................................... 96 Survival ..................................................................................................................................... 99 Food habits ............................................................................................................................. 103 Parakeet auklet ............................................................................................................................. 106 Food habits ............................................................................................................................. 106 Least auklet................................................................................................................................... 107 Survival ................................................................................................................................... 107 Food habits ............................................................................................................................. 121 i TABLE OF CONTENTS (continued) Page Crested auklet ............................................................................................................................... 124 Food habits ............................................................................................................................. 124 Horned puffin ................................................................................................................................ 125 Food habits ............................................................................................................................. 125 Tufted puffin .................................................................................................................................. 126 Food habits ............................................................................................................................. 126 Miscellaneous ............................................................................................................................... 127 Beach transects ...................................................................................................................... 127 COASST surveys .................................................................................................................... 129 Annotated list .......................................................................................................................... 145 Plants ..................................................................................................................................... 157 Sea surface temperature ......................................................................................................... 160 Seabird necropsies ................................................................................................................. 162 STAMP program ..................................................................................................................... 163 Observations at Otter Island .................................................................................................... 164 Observations at Walrus Island ................................................................................................
Recommended publications
  • Breeding Status and Population Trends of Seabirds in Alaska, 2014
    BREEDING STATUS AND POPULATION TRENDS OF SEABIRDS IN ALASKA, 2014 U.S. FISH AND WILDLIFE SERVICE AMNWR 2015/03 BREEDING STATUS AND POPULATION TRENDS OF SEABIRDS IN ALASKA, 2014 Compiled By: Donald E. Dragoo, Heather M. Renner and David B. Ironsa Key words: Aethia, Alaska, Aleutian Islands, ancient murrelet, Bering Sea, black-legged kittiwake, Cepphus, Cerorhinca, Chukchi Sea, common murre, crested auklet, fork-tailed storm-petrel, Fratercula, Fulmarus, glaucous-winged gull, Gulf of Alaska, hatching chronology, horned puffin, Larus, Leach’s storm-petrel, least auklet, long-term monitoring, northern fulmar, Oceanodroma, parakeet auklet, pelagic cormorant, Phalacrocorax, pigeon guillemot, Prince William Sound, productivity, red-faced cormorant, red-legged kittiwake, rhinoceros auklet, Rissa, seabirds, Synthliboramphus, thick-billed murre, tufted puffin, Uria, whiskered auklet. U.S. Fish and Wildlife Service Alaska Maritime National Wildlife Refuge 95 Sterling Highway, Suite 1 Homer, Alaska, USA 99603 February 2015 Cite as: Dragoo, D. E., H. M. Renner, and D. B. Irons. 2015. Breeding status and population trends of seabirds in Alaska, 2014. U.S. Fish and Wildlife Service Report AMNWR 2015/03. Homer, Alaska. aDragoo ([email protected]) and Renner ([email protected]), Alaska Maritime NWR, Homer; Irons ([email protected]), U. S. Fish and Wildlife Service, Migratory Bird Management, 1011 East Tudor Road, Anchorage, Alaska USA 99503 When using information from this report, data, results, or conclusions specific to a location(s) should not be used in other publications without first obtaining permission from the original contributor(s). Results and conclusions general to large geographic areas may be cited without permission. This report updates previous reports.
    [Show full text]
  • Andrew A. Schaffner; Stephen B. Mathewsf Judith E
    Andrew A. Schaffner; Stephen B. Mathewsf Judith E. Zeh* April 21, 1994 Abstract From June 1985 through June 1992 regular aerial surveys over Southeast Alaska, the Gulf of Alaska, and Aleutian Islands were conducted to monitor the distribution and abundance of Steller sea lions (Eumetopias jubatus). Furthermore, during 1992 the use of repetitive aerial surveys was introduced to study survey variability. The purposes of our present study were two-fold: (1) To investigate alternative statistical procedures for estimating population trend rates from aerial survey counts, and (2) to apply these procedures to the 1989-92 counts. We focused on 1989-92 because of the more abundant data for that period and to determine the most recent direction of population abundance relative to the well-documented steep decline prior to 1989. We concluded that parametric bootstrapping was the most appropriate interval estimation procedure. For this procedure the 90% confidence interval for the rate of change between the 1989 and 1992 Kenai-Kiska Recovery Plan trend site counts was (-10.19%, 2.62%). For +lJrookery and haul-out sites within the Kenai-Kiska region for which counts were made for both 1989 and 1992, the 90% confidence interval was (-6.20%, 6.81%). For sites outside the Kenai-Kiska region, the 90% confidence interval for the rate of change between 1989 and 1992 was (-37.92%, -6.93%). The parametric bootstrap procedure had the weakness of including data from only pairs of years; thus, 1990-91 information was excluded from the above interval estimates. Consequently, we investigated the use of both generalized linear modeling (GLM) and generalized estimating equations (GEE) as tools for analyzing all four years' data together.
    [Show full text]
  • Sea of Okhotsk: Seals, Seabirds and a Legacy of Sorrow
    SEA OF OKHOTSK: SEALS, SEABIRDS AND A LEGACY OF SORROW Little known outside of Russia and seldom visited by westerners, Russia's Sea of Okhotsk dominates the Northwest Pacific. Bounded to the north and west by the Russian continent and the Kamchatka Peninsula to the east, with the Kuril Islands and Sakhalin Island guarding the southern border, it is almost landlocked. Its coasts were once home to a number of groups of indigenous people: the Nivkhi, Oroki, Even and Itelmen. Their name for this sea simply translates as something like the ‘Sea of Hunters' or ‘Hunters Sea', perhaps a clue to the abundance of wildlife found here. In 1725, and again in 1733, the Russian explorer Vitus Bering launched two expeditions from the town of Okhotsk on the western shores of this sea in order to explore the eastern coasts of the Russian Empire. For a long time this town was the gateway to Kamchatka and beyond. The modern make it an inhospitable place. However the lure of a rich fishery town of Okhotsk is built near the site of the old town, and little and, more recently, oil and gas discoveries means this sea is has changed over the centuries. Inhabitants now have an air still being exploited, so nothing has changed. In 1854, no fewer service, but their lives are still dominated by the sea. Perhaps than 160 American and British whaling ships were there hunting no other sea in the world has witnessed as much human whales. Despite this seemingly relentless exploitation the suffering and misery as the Sea of Okhotsk.
    [Show full text]
  • A Preliminary Baseline Study of Subsistence Resource Utilization in the Pribilof Islands
    A PRELIMINARY BASELINE STUDY OF SUBSISTENCE RESOURCE UTILIZATION IN THE PRIBILOF ISLANDS Douglas W. Veltre Ph.D Mary J. Veltre, B.A. Technical Paper Number 57 Prepared for Alaska Department of Fish and Game Division of Subsistence Contract 81-119 October 15, 1981 ACKNOWLEDGMENTS . The authors would like to thank those numerous mem- bers of St. George and St. Paul who gave generously of their time and knowledge to help with this project. The Tanaq Corporation of St. George and the Tanadgusix Corporation of St. Paul, as well as the village councils of both communities, also deserve thanks for their cooperation. In addition, per- sonnel of the National Marine Fisheries Service in the Pribi- lofs provided insight into the fur seal operations. Finally, Linda Ellanna and Alice Stickney of the Department of Fish and Game gave valuable assistance and guidance, especially through their participation in field research. ii TABLE OF CONTENTS ACKNOWLEDGMENTS . ii Chapter I INTRODUCTION . 1 Purpose . 1 Research objectives . : . 4 Research methods . 6 Discussion of research methodology . 8 Organization of the report . 11 II BACKGROUND ON ALEUT SUBSISTENCE . 13 Introduction . 13 Precontact subsistence patterns . 15 The early postcontact period . 22 Conclusions . 23 III HISTORICAL BACXGROUND . 27 Introduction . 27 Russian period . 27 American period ........... 35 History of Pribilof Island settlements ... 37 St. George community profile ........ 39 St. Paul community profile ......... 45 Conclusions ......... ; ........ 48 IV THE NATURAL SETTING .............. 50 Introduction ................ 50 Location, geography, and geology ...... 50 Climate ................... 55 Fauna and flora ............... 61 Aleutian-Pribilof Islands comparison .... 72 V SUBSISTENCE RESOURCES AND UTILIZATION IN THE PRIBILOF ISLANDS ............ 74 Introduction ................ 74 Inventory of subsistence resources .
    [Show full text]
  • Status and Occurrence of Parakeet Auklet (Aethia Psittacula) in British Columbia
    Status and Occurrence of Parakeet Auklet (Aethia psittacula) in British Columbia. By Rick Toochin and Louis Haviland. Introduction and Distribution The Parakeet Auklet (Aethia psittacula) is a small species of auklet found breeding in the Beringia region of Alaska and Russia (Gaston and Jones 1998). This species has an Alaskan population estimated at 1 million birds (Gaston and Jones 1998). There is also a Russian population, but the exact population total is not known, due to a lack of population inventory work, but it is estimated to number about 400,000 birds with the vast majority, about 300,000 birds, found in the Sea of Okhotsk (Gaston and Jones 1998). The Parakeet Auklet has breeding colonies that are found on rocky mainland points and islands in the Gulf of Alaska (Jones et al. 2001). These sites include: Shumagin Island, Semidi Isand, Chirikof Island near Kodiak, locally in Kenai Peninsula and southeastern Alaska with small numbers south to St. Lazaria, Hazy and Forrester Island; and in the Aleutian Islands west to Buldir and Agattu Island; and in the Bering Sea at Little Diomede, St. Lawrence Island, King Island, St. Matthew Island, Pribilof Island and Nunivak Island (Sowls et al. 1978). The Parakeet Auklet also breeds in Russia in the Kurile Island chain with colonies on Chirinkontan, Lovushki, Raikoke, Matua, Yankicha, Simushir, Brat Chirpoev, Urup, and Iturup Island (Jones et al. 2001, Brazil 2009). They are also breeding on islands in the Sea of Okhotsk with colonies on Sakhalin, Tyuleniy, Iona, Talan, and Yamskyie Island (Jones et al. 2001, Brazil 2009). The Parakeet Auklet is also found breeding on Commander Island, and northwards locally along coast of the Kamchatka Peninsula, on Karaginski Island, Cape Navarin, and on Chukotka Peninsula (Konyukhov 1989, Kondratyev et al.
    [Show full text]
  • Population Estimates and Temporal Trends of Pribilof Island Seabirds
    POPULATION ESTIMATES AND TEMPORAL TRENDS OF PRIBILOF ISLAND SEABIRDS by F. Lance Craighead and Jill Oppenheim Alaska Biological Research P.O. BOX 81934 Fairbanks, Alaska 99708 Final Report Outer Continental Shelf Environmental Assessment Program Research Unit 628 November 1982 307 ACKNOWLEDGEMENTS Dan Roby and Karen Brink, University of Pennsylvania, Philadelphia, were especially helpful to us during our stay on St. George and shared their observations with us. Bob Day, University of Alaska, Fairbanks, also provided comparative data from his findings on St. George in 1981. We would like to thank the Aleut communities of St. George and St. Paul and Roger Gentry and other NMFS biologists on St. George for their hospitality and friendship. Bob Ritchie and Jim Curatolo edited an earlier version of this report. Mary Moran drafted the figures. Nancy Murphy and Patty Dwyer-Smith typed drafts of this report. Amy Reges assisted with final report preparation. Finally, we’d like to thank Dr. J.J. Hickey for initiating seabird surveys on the Pribi of Islands, which were the basis for this study. This study was funded by the Bureau of Land Management through interagency agreement with the National Oceanic and Atmospheric Administra- tion, as part of the Outer Continental Shelf Environmental Assessment Program. 308 TABLE OF CONTENTS ~ ACKNOWLEDGEMENTS. ● . ● . ● . ● . 308 EXECUTIVE SUMMARY . ✎ . ● ✎ . ● . ● ● . ✎ . ● ● . 311 INTRODUCTION. ✎ . ● ✎ . ✎ . ✎ ✎ . ● ✎ ● . ● ✎ . 313 STUDY AREA. ● . ✎ ✎ . ✎ . ✎ ✎ . ✎ ✎ ✎ . , . ● ✎ . ● . 315 METHODS . ● . ✎
    [Show full text]
  • THE PACIFIC WALRUS by KARL W
    332 Oryx THE PACIFIC WALRUS By KARL W. KENYON During recent years there have been repeated reports of extravagant exploitation of the walrus by Eskimos and these have been strengthened by aerial observation of many headless carcasses on beaches of the Bering Sea. So in 1958 the United States Fish and Wildlife Service decided upon an inquiry into the Pacific Walrus, and its hunting and utilization by Eskimo in the Bering Sea region. Biologists from the Department of Health, Education and Welfare, and the Alaska Department of Fish and Game co- operated in the work. Studies were conducted on St. Lawrence Island by Dr. Francis H. Fay and Mr. Averill Thayer, on Little Diomede Island by the late Mr. Stanley S. Fredericksen and the author, and on Round Island of the Walrus Islands in Bristol Bay, by Dr. Fay, Mr. James W. Brooks and the author. Dr. John L. Buckley of the Fish and Wildlife Service counted walruses on the ice of the northern Bering Sea from the air. The Eskimo hunters freely gave us their co-operation and good will, and this alone made the study possible. The economic incentive to exploit pinnipeds for oil and hides decreased after the chaotic slaughter of the eighteenth and nineteenth centuries when many species were seriously depleted. During the present century those which have continued to yield valuable products, such as elephant seals (Mirounga) and fur seals (Callorhinus and Arctocephalus), have been conserved. The Pacific walrus occupies a unique position in that the demand for its ivory, both carved and unworked, or raw, has increased in recent years, whereas measures introduced for conservation of the walrus have not yet been effective.
    [Show full text]
  • Breeding Biology of the Horned Puffin on St. Lawrence Island, Bering Sea, with Zoogeographical Notes on the North Pacific Puffins I
    Pacific Science (1973), Vol. 27, No.2, p. 99-119 Printed in Great Britain Breeding Biology of the Horned Puffin on St. Lawrence Island, Bering Sea, with Zoogeographical Notes on the North Pacific Puffins I SPENCER G. SEALY' THE HORNED PUFFIN (Fratercula corniculata) is one of six species ofalcids which regularly nest on Sevuokuk Mountain, 3 km east of Gambell on St. Lawrence Island, Alaska (Fig. 1). During the summers of 1966 and 1967, I conducted on this island a study of the breeding ecology of three of these species, the Parakeet Auklet (Cyc/orrf?ynchuspsittacula), Crested Auklet (Aethia cristatella), and Least Auklet (A. pusilla) (see Sealy, 1968). During these summers some ob­ servations on the breeding biology of the Horn­ ed Puffin were obtained and are reported here. The only life history study ofthis species which spans the entire breeding season is that of Swartz (1966) in the Cape Thompson region, Alaska, some 560 km north of St. Lawrence Island (Fig. 2). Numerous studies of the biology of the con­ generic Common Puffin (Fratercula arctica) of the Atlantic and Arctic oceans are available (e.g., Lockley, 1953; Be1opol'skii, 1957; Uspen­ ski, 1958; Myrberget, 1959, 1961, 1962; Kartas­ chew, 1960; Nettleship, 1972; and others) and some of these will be utilized here for compara­ tive purposes. When available, comparative ob­ servations on the breeding biology of the other Pacific puffins, the Rhinoceros Auklet (Ceror­ hinca monocerata), which is actually a puffin (Storer, 1945), and the Tufted Puffin (Lunda cirrhata) will also be included. DISTRIBUTION The breeding distribution of the Horned Puffin has been mapped recently by Udvardy (1963: 105).
    [Show full text]
  • Archeology, National Natural Landmarks, and State Game Sanctuaries: Combining Efforts for Science and Management
    Archeology, National Natural Landmarks, and State Game Sanctuaries: Combining Efforts for Science and Management Jeanne Schaaf, Judy Alderson, Joe Meehan, and Joel Cusick The sanctuary and the National Natural Landmarks program THE WALRUS ISLANDS STATE GAME SANCTUARY AND NATIONAL NATURAL LANDMARK (NNL) in Bristol Bay, Alaska, comprises a group of seven small islands about 63 miles southwest of Dillingham. During the 1950s, declining population numbers of the Pacific walrus (Odo- benus rosmarus) caused a great deal of concern about the future of the species. As a result, the state game sanctuary was established in 1960 “to protect the walruses and other game on the Walrus Islands”; it is managed by the Alaska Department of Fish and Game (ADF&G). Eight years later, the Walrus Islands National Natural Landmark was established to add nationwide recognition of the importance of this area for its concentration of Pacific walrus, with Round Island in particular serving as a summer haul-out for male walruses (see cover photo, this issue). It is one of the most southern of the walrus haul-outs and, at the time of establishment of the sanctuary and the NNL, it was one of the few remaining annual haul- outs in Alaska (and perhaps the only one consistently in use). The Walrus Islands are open to public access, but visitors to Round Island must obtain an access permit prior to arriving. The National Natural Landmarks Pro- lic’s appreciation of America’s natural her- gram recognizes and encourages the con- itage. The National Park Service adminis- servation of outstanding examples of our ters the NNL program, and, if requested, country’s natural history.It is the only natu- assists NNL owners and managers with the ral areas program of national scope that conservation of these important sites.
    [Show full text]
  • A Mass Post-Breeding Movement of Crested Auklets Aethia Cristatella in the Chukchi Sea
    Maftei & Russ et al.: Crested Auklets in the Chukchi Sea 31 A MASS POST-BREEDING MOVEMENT OF CRESTED AUKLETS AETHIA CRISTATELLA IN THE CHUKCHI SEA MARK MAFTEI1 & RODNEY RUSS2 1High Arctic Gull Research Group, Bamfield, BC V0R 1B0, Canada ([email protected]) 2Heritage Expeditions, Christchurch 8023, NZ Submitted 23 November 2013; accepted 16 January 2014 SUMMARY MAFTEI, M. & RUSS, R. 2014. A mass post-breeding movement of Crested Auklets Aethia cristatella in the Chukchi Sea. Marine Ornithology 42: 31–34. The Crested Auklet Aethia cristatella is a highly pelagic alcid for which non-breeding movements and distribution remain poorly understood. On 18 August 2013, in the vicinity of Cape Kekurnyi at the eastern end of the Chukotski Peninsula (66°9.2′N, 169°43.6′W), we observed an uninterrupted passage of an estimated 10 560 000 Crested Auklets over a period of four hours. At the peak of the movement, birds were passing at a rate exceeding 1 000 individuals per second. While the northward movement of Crested Auklets into the Chukchi Sea is well known, our observations indicate that birds from multiple breeding colonies congregate during the post-breeding season and travel in huge numbers to locally productive foraging areas. It also seems likely either that the global population of Crested Auklets has been previously underestimated, or that recent population increases have gone undetected. Key words: Chukchi Sea, Chukotski Peninsula, Crested Auklet, post-breeding movement, world population INTRODUCTION from the bridge and main deck of the ship. From our position at anchor approximately 1.5 km offshore of Uelen, virtually all of the In August and September of 2013, the ship Professor Khromov was migrating auklets were visible in one vertical field of view.
    [Show full text]
  • Monitoring of Populations and Productivity of Seabirds at St
    OCS Study MMS 90-0049 Monitoring Seabird Populations in Areas of Oil and Gas Development on the Alaskan Continental ShelE MONITORING OF POPULATIONS AND PRODUCTIVITY OF SEABIRDS AT ST. GEORGE ISLAND, CAPE PEIRCE, AND BLUFF, ALASKA, 1989 Final Report Edited by Vivian M. Mendenhall U. S. Fish & Wildlife Service Migratory Bird Management Marine and Coastal Bird Project Anchorage, Alaska OCS Study MMS 90-0049 MONITORING OF POPULATIONS AND PRODUCTIVITY OF SEABIRDS AT ST. GEORGE ISLAND, CAPE PIERCE, AND BLUFF, ALASKA, 1989 Edited by Vivian M. Mendenhall U.S. Fish and Wildlife Service Migratory Bud Management Marine and Coastal Birds Project 101 1 East Tudor Rd. Anchorage, Alaska 99503 Submitted to: Minds Management Service Environment Studies Unit 949 East 36th Avenue Anchorage, Alaska 995 10 April 1991 The opinions, findings, conclusions, or recommendations expressed in this report are those of the authors and do not necessarily reflect the views of the Minerals Management Service, nor does mention of trade names or commercial products constitute endorsement or recommendation for use by the Federal Government of the United States. TABLE OF CONTENTS LIST OF TABLES ......................................................................................................... v LIST OF RGURES ........................................................................................................... ix ABSTRACT ..................................................................................................................... xi 1. INTRODUCTION................................................................................................
    [Show full text]
  • SEX and AGE SEGREGATION of SEA OTTERS by Karl B
    ALASKA DEPARTMENT OF FISH AND GAME JUNEAU, ALASKA SEX AND AGE SEGREGATION OF SEA OTTERS By Karl B. Schneider STATE OF ALASKA Jay S. Hammond, Governor DIVISION OF GAME Robert A. Rausch, Director Donald E. McKnight, Research Chief DEPARTMENT OF FISH AND GAME Ronald 0. Skoog, Commissioner Final Report Federal Aid in Wildlife Restoration Projects W-17-4 through W-17-8 Job 8.9R (Printed April 1978) FINAL REPORT (RESEARCH) State: Alaska Cooperator: Karl B. Schneider Project Title: Marine Mammal Investigations Project Nos.: W-17-4 thru W-17-8 Job No. : Job Title: Sex and Age Segregation of Sea Otters Period Covered: July 1, 1971 to June 30, 1976 SUMMARY Knowledge of patterns of geographical segregation of sea otters by sex and age is essential to any active conservation and management program on that species. The sexes and ages of sea otters harvested or captured from several Alaskan populations were examined by specific location and season to determine patterns of segregation. All populations contained large female areas where most adult females and dependent pups in the population were found. The number of sexually mature males over 5 years old in female areas fluctuated seasonally and was positively correlated with the number of estrous females. Sexually immature males between the ages of 1 and 6 years appeared to be actively excluded from female areas. Where high densities of sea otters were continuous and range expansion had ceased, many adult males and most immature males concentrated in geographically discrete male areas. Permanently established male areas did not exist in some populations where areas of high sea otter density were separated by areas of low density or where the population was expanding into vacant habitats.
    [Show full text]