An Eastern Wild Turkey Population Dynamics Model for Virginia and West Virginia

Alpizar‐Jara, Russell; Brooks, Elizabeth N.; Pollock, Kenneth H.; Steffen, David E.; Pack, James C.; Norman, Gary W.

doi:10.2307/3803093

Cited by 28 publications

(70 citation statements)

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“…Lower harvest rates of 10–12% are additive in wild turkeys (Pack et al. 1999; Alpizar‐Jara et al. 2001), which might be expected for a large‐bodied gamebird.…”

Section: Discussionmentioning

confidence: 99%

Is hunting mortality additive or compensatory to natural mortality? Effects of experimental harvest on the survival and cause-specific mortality of willow ptarmigan

Sandercock

Nilsen

Brøseth

et al. 2010

Journal of Animal Ecology

159

213

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Summary1. The effects of harvest on the annual and seasonal survival of willow ptarmigan Lagopus lagopus L. were tested in a large-scale harvest experiment. Management units were randomly assigned to one of three experimental treatments: 0%, 15% or 30% harvest. Seasonal quotas were based on the experimental treatment and estimates of bird density before the hunting season. Survival rates and hazard functions for radio-marked ptarmigan were then estimated under the competing risks of harvest and natural mortality. 2. The partially compensatory mortality hypothesis was supported: annual survival of ptarmigan was 0AE54 ± 0AE08 SE under 0% harvest, 0AE47 ± 0AE06 under 15% harvest, and was reduced to 0AE30 ± 0AE05 under 30% harvest. Harvest mortality increased linearly from 0AE08 ± 0AE05, 0AE27 ± 0AE05 and 0AE42 ± 0AE06 from 0% to 30% harvest, whereas natural mortality was 0AE38 ± 0AE08, 0AE25 ± 0AE05 and 0AE28 ± 0AE06 under the same treatments. 3. Realized risk of harvest mortality was 0AE08-0AE12 points higher than our set harvest treatments of 0-30% because birds were exposed to risk if they moved out of protected areas. The superadditive hypothesis was supported because birds in the 30% harvest treatment had higher natural mortality during winter after the hunting season. 4. Natural mortality was mainly because of raptor predation, with two seasonal peaks in fall and spring. Natural and harvest mortality coincided during early autumn with little potential for compensation during winter months. Peak risk of harvest mortality was 5· higher than natural mortality. Low natural mortality during winter suggests that most late season harvest would be additive mortality. 5. Environmental correlates of natural mortality of ptarmigan included seasonal changes in snow cover, onset of juvenile dispersal, and periods of territorial activity. Natural mortality of ptarmigan was highest during autumn movements and nesting by gyrfalcons Falco rusticolus L. Mortality was low when gyrfalcons had departed for coastal wintering sites, and during summer when ptarmigan were attending nests and broods. 6. Our experimental results have important implications for harvest management of upland gamebirds. Seasonal quotas based on proportional harvest were effective and should be set at £15% of August populations for regional management plans. Under threshold harvest of a reproductive surplus, 15% harvest would be sustainable at productivity rates ‡2AE5 young per pair. Impacts of winter harvest could be minimized by closing the hunting season in early November or by reducing late season quotas.

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“…Lower harvest rates of 10–12% are additive in wild turkeys (Pack et al. 1999; Alpizar‐Jara et al. 2001), which might be expected for a large‐bodied gamebird.…”

Section: Discussionmentioning

confidence: 99%

Is hunting mortality additive or compensatory to natural mortality? Effects of experimental harvest on the survival and cause-specific mortality of willow ptarmigan

Sandercock

Nilsen

Brøseth

et al. 2010

Journal of Animal Ecology

159

213

View full text Add to dashboard Cite

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“…For male wild turkeys ( Meleagris gallapavo ), spring harvest is the single greatest mortality factor (Godwin et al 1991, Paisley et al 1996, Wright and Vangilder 2005) and is thought to be additive to other sources of mortality because most natural mortality occurs during the spring breeding season (Thogmartin and Schaeffer 2000, Holdstock et al 2006, Moore et al 2008). Although fall harvest is thought to have the greatest influence on population growth (Vangilder and Kurzejeski 1995, Alpizar‐Jara et al 2001, McGhee et al 2008), spring harvest can influence the number and proportion of adult gobblers in the population (Vangilder and Kurzejeski 1995). For example, Vangilder and Kurzejeski (1995) modeled a wild turkey population and by increasing overall spring harvest rates from 25% to 50%, the proportion of the population composed of adults declined from 72% to 56%.…”

mentioning

confidence: 99%

Variation in spring harvest rates of male wild turkeys in New York, Ohio, and Pennsylvania

et al. 2011

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Spring harvest rates of male wild turkeys (Meleagris gallapavo) influence the number and proportion of adult males in the population and turkey population models have treated harvest as additive to other sources of mortality. Therefore, hunting regulations and their effect on spring harvest rates have direct implications for hunter satisfaction. We used tag recovery models to estimate survival rates, investigate spatial, temporal, and demographic variability in harvest rates, and assess how harvest rates may be related to management strategies and landscape characteristics. We banded 3,266 male wild turkeys throughout New York, Ohio, and Pennsylvania during 2006–2009. We found little evidence that harvest rates varied by year or management zone. The proportion of the landscape that was forested within 6.5 km of the capture location was negatively related to harvest rates; however, even though the proportion forested ranged from 0.008 to 0.96 across our study area, this corresponded to differences in harvest rates of only 2–5%. Annual survival was approximately twice as high for juveniles $({\hat {S}} = 0.64- 0.87)$ as adults $({\hat {S}} = 0.30- 0.41)$. In turn, spring harvest rates for adult turkeys were greater for adults $({\hat {H}} = 0.35- 0.39)$ than juveniles $({\hat {H}} = 0.17- 0.27)$. We estimated the population of male turkeys in New York and Pennsylvania ranged from 104,000 to 132,000 in all years and ranged from 63,000 to 75,000 in Ohio. Because of greater harvest rates for adult males, the proportion of adult males in the population was less than in the harvest and ranged from 0.40 to 0.81 among all states and years. The high harvest rates observed for adults may be offset by greater recruitment of juveniles into the adult age class the following year such that these states can sustain high harvest rates yet still maintain a relative high proportion of adult males in the harvest and population. © 2011 The Wildlife Society.

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“…Given that multiple hunting seasons occur annually, it is intuitive that larger spring harvests should leave less room for large fall harvests. Thus, when our results are considered in light of earlier modeling studies that often used optimistic parameter combinations (i.e., high productivity, equal fall harvest vulnerability, and low spring harvest; Alpizar-Jara et al 2001, McGhee et al 2008 relative to the broader range of values we considered for structurally uncertain parameters, more conservative harvest recommendations are not a surprise. In our case, the effect of additional structural uncertainty was exacerbated by the high sensitivity of optimal fall harvest rates to the values of model parameters (optimal target harvest rates ranged from 0% to >10%, Fig.…”

Section: Target Reference Points For Management Of Fall Wild Turkey Hmentioning

confidence: 90%

“…1; Vangilder 1992, Vangilder and Kurzejeski 1995, Alpizar-Jara et al 2001. Past studies often evaluated performance of proportional fall Turkey harvests for achieving simplified objectives relative to the modern context of management.…”

Section: Structuring Harvest Management Decisionmentioning

confidence: 99%

“…The set of possible target fall harvest rates was 0-15%, at increments of 1%, where a harvest of 15% of the fall population was the largest reported as sustainable in previous modeling studies ( Alpizar-Jara et al 2001). The set of possible target fall harvest rates was 0-15%, at increments of 1%, where a harvest of 15% of the fall population was the largest reported as sustainable in previous modeling studies ( Alpizar-Jara et al 2001).…”

Section: Structuring Harvest Management Decisionmentioning

confidence: 99%

See 1 more Smart Citation

Identifying target reference points for harvesting assessment‐limited wildlife populations: a case study

Stevens

Bence

Porter

et al. 2017

Ecological Applications

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Identifying appropriate strategies for sustainable harvest is a challenge for many terrestrial vertebrate species because of uncertain system dynamics, limited data to inform population models, and potentially conflicting objectives that seek to harvest and maintain populations at desirable levels. The absence of monitoring and assessment infrastructure needed to regularly estimate abundance accentuates this challenge for many species, and limits application of rigorous state-dependent frameworks for decision making that are commonly advocated in natural resource management. Reference points, which define management targets or triggers for changing management, are often used to guide decision-making, but suffer from ambiguity when developed without explicit consideration of uncertainty or trade-offs among competing objectives. We describe an approach for developing unambiguous target reference points for assessment-limited species using structured decision making, and demonstrate the approach to develop target harvest rates for management of fall Wild Turkey (Meleagris gallopavo) harvests in the face of uncertain population and harvest dynamics. We use simulation and decision analyses to identify harvest rates that are optimal for accomplishing explicit management objectives in the face of uncertainty, and harvest rates with robust performance over broad regions of the demographic and harvest model parameter space. We demonstrate that population and harvest parameters commonly uncertain to wildlife managers interact to determine appropriate target harvest rates for Wild Turkeys, and that formally acknowledging a range of plausible values for structurally uncertain parameters results in more conservative target reference points than suggested by previously published studies. The structured decision making framework described here provides a natural conceptual and quantitative framework for extending our approach to develop unambiguous harvest targets for other assessment-limited wildlife populations while formally acknowledging structural uncertainty in system dynamics.

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An Eastern Wild Turkey Population Dynamics Model for Virginia and West Virginia

Cited by 28 publications

References 0 publications

Is hunting mortality additive or compensatory to natural mortality? Effects of experimental harvest on the survival and cause-specific mortality of willow ptarmigan

Is hunting mortality additive or compensatory to natural mortality? Effects of experimental harvest on the survival and cause-specific mortality of willow ptarmigan

Variation in spring harvest rates of male wild turkeys in New York, Ohio, and Pennsylvania

Identifying target reference points for harvesting assessment‐limited wildlife populations: a case study

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