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We determined wolverine (Gulo gulo) distribution and occurrence probabilities using aerial surveys and hierarchical spatial modeling in a 180,000-km 2 portion of Interior Alaska, USA. During 8 February-12 March 2006, we surveyed 149 of 180 1,000-km 2 sample units for wolverine tracks. We observed wolverine tracks in 99 (66.4%) sample units. Wolverine detection probability was L 69% throughout the survey period. Posterior occurrence probabilities of whether a wolverine track occurred in a sample unit was dependent on survey timing, number of transects flown, number of neighboring sample units with detected tracks, percentage of the sample unit with elevation M 305 m, and human influences. Our model indicated strong evidence of occurrence (.0.80) in 72% of the 180 survey units, strong evidence of absence (,0.20) in 12%, and weak evidence of occurrence or absence (0.20-0.80) in 16%. Wolverine area of occupancy made up 83% of the study area. Simulations illustrated that 2-4 survey routes were necessary for the survey technique to provide strong evidence of wolverine presence or absence in Interior Alaska if a track was not identified along the first route. The necessary number of survey routes depends on the occurrence probability in a sample unit. We provided managers with a map of wolverine distribution in Interior Alaska and an efficient and lower-cost method to detect coarse-scale changes in wolverine distribution. Our technique was effective in both Interior Alaska and Ontario, Canada, suggesting it would be effective throughout most of the boreal forest range of wolverines where tracks can be readily observed from the air. The technique requires a certain skill level in recognizing tracks; it is essential that tracks are identified correctly and training may be necessary depending on surveyor experience.

A diverse, international Fortymile Planning Team wrote a novel Fortymile caribou herd {Rangifer tarandus granti) Management Plan in 1995 (Boertje & Gardner, 1996: 56-77). The primary goal of this plan is to begin restoring the Fortymile herd to its former range; >70% of the herd's former range was abandoned as herd size declined. Specific objectives call for increasing the Fortymile herd by at least 5-10% annually from 1998-2002. We describe demographics of the herd, factors limiting the herd, and condition of the herd and range during 1992-1997. These data were useful in proposing management actions for the herd and should be instrumental in future evaluations of the plan's actions. The following points summarize herd biology relevant to management proposed by the Fortymile Planning Team: 1. Herd numbers remained relatively stable during 1990-1995 (about 22 000-23 000 caribou). On 21 June 1996 we counted about 900 additional caribou in the herd, probably a result of increased pregnancy rates in 1996. On 26 June 1997 we counted about 2500 additional caribou in the herd, probably a result of recruitment of the abundant 1996 calves and excellent early survival of the 1997 calves. The Team deemed that implementing management actions during a period of natural growth would be opportune. 2. Wolf (Cants lupus) and grizzly bear (Ursus arctos) predation were the most important sources of mortality, despite over a decade of the most liberal regulations in the state for harvesting of wolves and grizzly bears. Wolves were the most important predator. Wolves killed between 2000 and 3000 caribou calves annually during this study and between 1000 and 2300 older caribou; 1200-1900 calves were killed from May through September. No significant differences in annual wolf predation rates on calves or adults were observed between 1994 and early winter 1997. Reducing wolf predation was judged by the Team to be the most manageable way to help hasten or stimulate significant herd growth. To reduce wolf predation, the Team envisioned state-sponsored wolf translocations and fertility control in 15 key wolf packs during November 1997-May 2001. Also, wolf trappers were encouraged to shift their efforts to specific areas. 3. To increase social acceptance of the management plan, the Fortymile Team proposed reducing the annual caribou harvest to 150 bulls for 5 years beginning in 1996. Reducing annual harvests from 200-500 bulls (<2% of the herd, 1990-1995) to 150 bulls (<1% of the herd, 1996-2000) will not result in the desired 5-10% annual rates of herd increase. 4. We found consistent evidence for moderate to high nutritional status in the Fortymile herd when indices were compared with other Alaskan herds (Whitten et al, 1992;Valkenburg, 1997). The single evidence for malnutrition during 1992-1997 was the low pregnancy rate during 1993 following the abnormally short growing season of 1992. However, this low pregnancy rate resulted in no strong decline in Fortymile herd numbers, as occurred in the Delta and Denali herds . No sign...

Understanding the limiting factors of a prey population is important before and during predator control programs, and optimal intensive management of an increasing prey population requires formal recognition of a sustainable population size. The migratory Fortymile caribou (Rangifer tarandus) herd in Alaska reached a low of approximately 6,000 caribou during 1973–1975. To regain peak numbers of approximately 50,000 caribou estimated in the 1960s, stakeholder groups gained approval for conservative harvest rates (1973–2013) and periods of restricted nonlethal (1998–2004) and lethal wolf (Canis lupus) control (2005–2013). We studied demography of the herd using radio‐telemetry during 1990–2014, when herd size increased from about 22,000 to 52,000 caribou. Parturition rates in the early 1990s were among the highest reported, but parturition rates of primiparous females subsequently declined to a level indicating resource‐limitation as caribou numbers approached and then exceeded 50,000. This and companion studies documented several other cautionary signals to an eventual decline, including declining October calf weights, early summer movement off the alpine and subalpine tundra to lower elevation spruce–moss taiga, relatively high caribou densities, a nearly 40‐year history of increasing caribou numbers, and a return to previous peak numbers. We studied mortality of calves and older females during the 4 years before wolf control and the first 5 years of nonlethal wolf control. During those 9 years, annual mortality rates averaged 54% for calves and 9% for adult females. We detected no convincing support for decreased wolf predation during nonlethal control. We also detected no support for increased caribou survival during nonlethal or lethal wolf control. Based on counts of caribou during summer aggregations using a total search photocensus technique, rate of herd increase (λr) was negligible (λr = 1.00) during 1990–1995, highest during the 3 years immediately before nonlethal wolf control (λr = 1.11, 1995–1998), moderate during nonlethal wolf control (λr = 1.07, 1998–2003), and low during the period that included the first 5 years of lethal wolf control (λr = 1.02, 2003–2010). We combined observed cause of death with the 9 annual modeled starting populations (all newborn calves and adults) and estimated that wolves killed 10–15% of the populations annually, grizzly bears (Ursus arctos) killed 4–7%, other predators killed 2–4%, nonpredation factors killed 1–2%, and hunters killed ≤2%. Wolves killed 5–9% of the annual populations as calves and 5–6% as adults. In retrospect, nonlethal wolf control efforts were too localized to decrease wolf numbers (e.g., adjacent untreated wolf packs reached max. mean numbers). Lethal wolf control efforts had only seasonal and localized effects on wolf numbers. It is important that stakeholders focus on describing a preferred, sustainable herd size, or nutritional status and proceed toward managing this increasing herd in a sustainable manner because, when ungulates overshoo...

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