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The effects of breeder loss on wolves

Brainerd S.M., Andren H., Bangs E.E., Bradley E.H., Fontaine J.A., Hall W., Iliopoulos Y., Jimenez M.D., Jozwiak E.A., Liberg O., Mack C.M., Meier T.J., Niemeyer C.C., Pedersen H.C., Sand H., Schultz R.N., Smith D.W., Wabakken P., Wydeven A.P.


DOI  10.2193/2006-305
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Published 2008

Abstract

Managers of recovering wolf (Canis lupus) populations require knowledge regarding the potential impacts caused by the loss of territorial, breeding wolves when devising plans that aim to balance population goals with human concerns. Although ecologists have studied wolves extensively, we lack an understanding of this phenomenon as published records are sparse. Therefore, we pooled data (n = 134 cases) on 148 territorial breeding wolves (75 M and 73 F) from our research and published accounts to assess the impacts of breeder loss on wolf pup survival, reproduction, and territorial social groups. In 58 of 71 cases (84%), =1 pup survived, and the number or sex of remaining breeders (including multiple breeders) did not influence pup survival. Pups survived more frequendy in groups of =6 wolves (90%) compared with smaller groups (68%). Auxiliary nonbreeders benefited pup survival, with pups surviving in 92% of cases where auxiliaries were present and 64% where they were absent. Logistic regression analysis indicated that the number of adult-sized wolves remaining after breeder loss, along with pup age, had the greatest influence on pup survival. Territorial wolves reproduced the following season in 47% of cases, and a greater proportion reproduced where one breeder had to be replaced (56%) versus cases where both breeders had to be replaced (9%). Group size was greater for wolves that reproduced the following season compared with those that did not reproduce. Large recolonizing (>75 wolves) and saturated wolf populations had similar times to breeder replacement and next reproduction, which was about half that for small recolonizing (=75 wolves) populations. We found inverse relationships between recolonizing population size and time to breeder replacement (r = -0.37) and time to next reproduction (r = -0.36). Time to breeder replacement correlated strongly with time to next reproduction (r = 0.97). Wolf social groups dissolved and abandoned their territories subsequent to breeder loss in 38% of cases. Where groups dissolved, wolves reestablished territories in 53% of cases, and neighboring wolves usurped territories in an additional 21% of cases. Fewer groups dissolved where breeders remained (26%) versus cases where breeders were absent (85%). Group size after breeder loss was smaller where groups dissolved versus cases where groups did not dissolve. To minimize negative impacts, we recommend that managers of recolonizing wolf populations limit lethal control to solitary individuals or territorial pairs where possible, because selective removal of pack members can be difficult. When reproductive packs are to be managed, we recommend that managers only remove wolves from reproductive packs when pups are =6 months old and packs contain =6 members (including =3 ad-sized wolves). Ideally, such packs should be close to neighboring packs and occur within larger (=75 wolves) recolonizing populations.

Keywords:

breeding population; canid; hunting; logistics; nature conservation; regression analysis; reproduction; social organization; survival; territory; wildlife management; Canidae; Canis familiaris; Canis lupus

Full Citation

Brainerd, S.M., Norwegian Institute for Nature Research, c/o Norwegian Association of Hunters and Anglers, P.O. Box 94, NO-1378 Nesbru, Norway; Andrén, H., Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agriculture Sciences, SE-73091 Riddarhyttan, Sweden; Bangs, E.E., United States Fish and Wildlife Service, 585 Shepard Way, Helena, MT 59601, United States; Bradley, E.H., Montana Fish, Wildlife, and Parks, 730 N Montana Street, Dillon, MT 59725, United States; Fontaine, J.A., United States Fish and Wildlife Service, 585 Shepard Way, Helena, MT 59601, United States, United States Fish and Wildlife Service, Theodore Roosevelt National Wildlife Refuge Complex, 728 Yazoo Refuge Road, Hollandale, MS 38748, United States; Hall, W., Wisconsin Department of Natural Resources, Sandhill Wildlife Area, P.O. Box 156, Babcock, WI 54413, United States; Iliopoulos, Y., Callisto Wildlife and Conservation Society, Nikiforos Foka 5, Thessalonica, GR-54621, Greece; Jimenez, M.D., United States Fish and Wildlife Service, P.O. Box 2645, Jackson, WY 83001, United States; Jozwiak, E.A., United States Fish and Wildlife Service, Kenai National Wildlife Refuge, P.O. Box 2139, Soldotna, AK 99669, United States; Liberg, O., Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agriculture Sciences, SE-73091 Riddarhyttan, Sweden; Mack, C.M., Nez Perce Tribe Wolf Recovery, Department of Wildlife Management, 1000 Mission, McCall, ID 83638, United States; Meier, T.J., National Park Service, Denali National Park and Preserve, P.O. Box 9, Denali Park, AK 99755, United States; Niemeyer, C.C., United States Fish and Wildlife Service, 1387 S Vinnel Way, Boise, ID 83709, United States, 3314 Cherry Lane, Boise, ID 83705, United States; Pedersen, H.C., Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway; Sand, H., Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agriculture Sciences, SE-73091 Riddarhyttan, Sweden; Schultz, R.N., Wisconsin Department of Natural Resources, Endangered Resources, 8770 Highway J., Woodruff, WI 54568, United States; Smith, D.W., Yellowstone Center for Resources, Wolf Project, P.O. Box 168, Yellowstone National Park, WY 82190, United States; Wabakken, P., Hedmark University College, Faculty of Forestry and Wildlife Management, NO-2480 Koppang, Norway; Wydeven, A.P., Wisconsin Department of Natural Resources, 875 S 4th Street, Park Falls, WI 54552, United States


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