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Figure 14.3. Isle Royale National Park: (a) Wolf and moose populations since 1959. (b) Wolf pack territories in the winter of 1999. In that year the sizes of the packs were: 11 in East Pack III (EPIII), 10 in Middle Pack II (MP II) and 2 in West Pack II (WP II). (c) Moose distribution in the February 1999 census. (All figures are from Peterson 1999 and reproduced with permission of Dr. Rolf Peterson)

Figure 14.4. Typical distribution of RLU markings in and around a wolf pack territory in northeastern Minnesota. The levels of scent marking both due to the resident pack and its neighbours are greatest around the territory edges. The different shapes (filled squares and circles, open squares, circles and triangles) denote markings from different packs. (From Peters and Mech (1975) and reproduced with permission of Dr. David Mech)

Figure 14.4. Typical distribution of RLU markings in and around a wolf pack territory in northeastern Minnesota. The levels of scent marking both due to the resident pack and its neighbours are greatest around the territory edges. The different shapes (filled squares and circles, open squares, circles and triangles) denote markings from different packs. (From Peters and Mech (1975) and reproduced with permission of Dr. David Mech)

extent, overlap only along their edges as shown in Figures 14.2 and 14.3. These territories effectively partition jurisdiction over spatially distributed prey resources.

The precise details of wolf behavior and ecology depend on local habitat conditions: there are, for example, basic differences between the habitat on Isle Royale and on the mainland. Although we concentrate on northeastern Minnesota, we believe the main results have applicability to other areas and other territorial mammals. This has been shown to be the case in the interesting study by Moorcroft et al. (1999) on coyotes (Canis latrans) which we discuss later. Wolf activities occur over various timescales— yearly, seasonally and daily. Thus a key element in modelling these wolf activities is the determination of an appropriate timescale.

Seasonality plays an important role in both wolf and deer ecology as is particularly evident in the reproductive behaviours of both species. Wolves produce young in the spring; pups arrive in April or May and activity centres around the den throughout the summer. Deer produce fawns in the early summer. Throughout the rest of the year,

Figure 14.5. Winter yards and summer ranges of radio-collated deer in relation to wolf pack territories. (From Hoskinson and Mech 1976 and reproduced with permission of the Wildlife Society (copyright holder))

any changes in population levels are due to mortality, emigration or immigration. The entire wolf pack helps with feeding the pups (Mech 1970); adults make daily excursions and return with food. In late summer, as the pups become stronger, the den may be abandoned in favor of above-ground rendezvous sites. In the fall and winter, pups are able to move and travel widely with the pack, rarely returning to the den or rendezvous sites. In our modelling of pack territory dynamics we shall not include the yearly birth and death processes (see White 1995), but concentrate on the short term behavioral and movement dynamics.

In formulating the model we make no underlying assumptions about the size and extent of the wolf territories themselves; we show that the territorial patterns actually arise naturally as stable steady state solutions to the model equations. These mathematically generated territorial patterns share key features with field observations including buffer zones between adjacent packs, where wolves are scarce and increased levels of scent marking near territorial boundaries. The material in this chapter develops the model and analyzes it in detail. Among other aspects we show how behavioral responses to foreign scent marks determines the qualitative form of resulting spatial territories.

Very few quantitative models have been derived to explain the spatial dynamics of territories when competition for space is a key factor. As far as we are aware, the model and variations we describe here (Lewis and Murray 1993, White 1995, White et al. 1996a,b) comprise the only spatially explicit formulation designed to show how pack territories form over time based on behavioral interactions. On the other hand, field studies of pack territoriality have been extensive, and include observations of a variety of predatory mammals other than wolves, such as lions, badgers, hyenas and African wild dogs (references to all of these are given in White et al. 1998).

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