Henry Campa

Mortality patterns of white-tailed deer in Michigan's Upper Peninsula.

We radiotracked 95 white-tailed deer (Odocoileus virginianus, all age classes) in Michigans Upper Peninsula between January 1992 and January 1995 for a total of 38,888 deer-days. Fifty-eight deer died: 12 due to predation, 6 due to malnutrition, 14 due to other or unknown sources, and 26 killed by hunters (including 1 that was poached). Analysis of mortality indicated rates of annual nonhunting mortality were 0.19 (SE = 0.09) for adult females, 0.00 (SE = 0.05) for adult males and yearling females, and 0.16 (SE = 0.07) for yearling males. Hunting mortality was 0.04 (SE = 0.10) for adult females, 0.72 (SE = 0.12) for adult males, 0.12 (SE = 0.09) for yearling females, and 0.47 (SE = 0.10) for yearling males. Hunting mortality was higher among males in both age classes (P < 0.01) though nonhunting mortality was equivalent (P ≥ 0.05). Seasonal mortality rates of males and females differed during the fall (P < 0.001), coincident with Michigans hunting seasons. Hunting mortality was significantly higher for yearling and adult males due to hunting regulations that limited harvest of antlerless deer; consequently, adult sex ratios were skewed towards females.

Avian Abundance in CRP and Crop Fields during Winter in the Midwest

Abstract We compared the abundance and species composition of birds in Conservation Reserve Program (CRP) fields with the same aspects in row-crop fields during the winter (January and February) over several years (1992–1995) for six midwestern states (Indiana, Iowa, Kansas, Michigan, Missouri and Nebraska). Field techniques were standardized in all states. CRP fields consisted of either permanent introduced grasses and legumes (CP1) or permanent native grasses (CP2), and the plant species seeded in CRP fields differed within and among states. Vegetation characteristics of CRP fields varied considerably from state to state, but vertical density and total canopy cover (primarily grasses) were particularly high in Nebraska. Mean annual total bird abundance ranged from 0.1 to 5.1 birds per km of transect in CRP fields and from 0.1 to 24.2 in row-crop fields. The total number of bird species recorded in CRP fields in the six states ranged from 6 to 32; the range for row-crop fields was 8 to 18. The most abundant species in CRP fields differed among states but included the ring-necked pheasant, American tree sparrow, northern bobwhite, dark-eyed junco and American goldfinch. The most abundant species in row-crop fields included the horned lark, American tree sparrow, European starling, mourning dove, lapland longspur, meadowlarks and Canada goose. Some of the most abundant bird species wintering on CRP fields have been undergoing long-term population declines, thus this program has the potential to mitigate population losses.

Cause-Specific Mortality and Survival of White-Tailed Deer Fawns in Southwestern Lower Michigan

Abstract Understanding white-tailed deer (Odocoileus virginianus) fawn survival is critical for managing herd dynamics and setting effective harvest regulations. We fitted white-tailed deer fawns with radiocollars during spring 2001 (n = 35) and 2002 (n = 40) to quantify cause-specific mortality, survival, and home-range size and composition in the southwestern Lower Peninsula of Michigan, USA. We monitored fawns a minimum of twice a week until they died, were censored, or the tracking period ended. Seventeen of 75 fawns died. The primary causes of mortality were legal hunting (n = 5) and deer–vehicle collisions (n = 5). Other causes included dehydration, bacterial infection, suspected coyote (Canis latrans) predation, drowning, and malnutrition. Survival probabilities for 2001 and 2002 radiocollared fawns to 30 days postcapture were 0.97 and 0.93, respectively. Capture-to-prehunt (127 days) fawn-survival probabilities were 0.91 for 2001 fawns and 0.90 for 2002 fawns. Posthunt (220 days) fawn survival probabilities were 0.76 for 2001 fawns and 0.85 for 2002 fawns. Annual estimated fawn-survival probabilities were 0.76 for 2001 and 0.75 for 2002. Mean annual home-range size for fawns was 75.36 ha. Habitat quality and land cover and use were potential factors that contributed to our high fawn survival. Our results can aid wildlife biologists in developing, refining, and validating deer population models as well as devising and balancing white-tailed deer population management decisions in an agroforested landscape.

White-tailed deer management options model (DeerMOM): design, quantification, and application

Abstract The deer management options model (DeerMOM) is a computer simulation model designed to assess the effects of management options on population size, sex and age structure of white-tailed deer (Odocoileus virginianus). In this model, we grouped deer into three age classes: fawn, yearling, and adult. Reproductive rates and fetal sex ratios were age-specific, while natural and harvest mortality rates were both age- and sex-specific. DeerMOM was parameterized to represent the deer population in the Upper Peninsula of Michigan, USA. Effects of winter severity were incorporated into the model. Population estimates derived from annual pellet group surveys were used to validate the model. Different management options were evaluated using two criteria: a quantity goal (number of deer) and a quality goal (percentage of antlered bucks in the deer population). Simulation results indicated that current management practices (with a high rate of buck harvest) resulted in high deer numbers with a low percentage of antlered bucks. Under the condition of high buck harvest rate, increasing doe harvest did not achieve both the quantity and the quality goals simultaneously. Moderate harvest of both sexes would control population growth and increase the percentage of antlered bucks. The simulations also showed that winter weather conditions and doe harvest shaped deer population trends but buck harvest determined the percentage of antlered bucks. Our findings indicated that quality deer management objectives can be reached only by lowering buck harvest rates while simultaneously increasing the doe harvest. The best option for achieving both the quantity and the quality goals was moderate harvest of bucks and does without sex bias.

Applying Landscape-Scale Habitat-Potential Models to Understand Deer Spatial Structure and Movement Patterns

Abstract Ecologically based management must incorporate components that consider how individuals associate temporally and spatially to environments that provide specific habitat requirements. Recent research has assessed how environments could be classified based on potential to provide deer (Odocoileus virginianus) habitat components. If habitat potential (HP; i.e., capability of habitat types to provide annual life requisites) classifications can be correlated to deer spatial structure and seasonal movement patterns, managers could better understand how spatial distribution of habitat components influences deer distribution. We analyzed home-range distribution and seasonal movement patterns from 45 adult (≥2 yr old) female deer radiocollared between 1999–2002, and deer habitat characteristics in northeastern Lower Peninsula, Michigan, USA, to investigate whether we can predict deer seasonal movement patterns based on the distribution of HP. We constructed logistic regression models that calculated the probability of deer migration given specific HP within seasonal home ranges of migratory and nonmigratory deer. Our results suggested that the probability of seasonal deer migrations relates to the juxtaposition (arrangement) of different habitat types that collectively provide all annual life requisites. We demonstrated that use of habitat-type classifications and HP models can track and predict deer movement patterns, which can facilitate establishment of management units and ecologically based deer management practices.

Development of landscape-scale habitat-potential models for forest wildlife planning and management

Abstract Wildlife biologists use current land-cover databases to understand wildlife—habitat relationships but must make assumptions about potential vegetation and successional dynamics when predicting species responses to ecological changes. Understanding the potential of habitat types to provide wildlife habitat components throughout succession, as opposed to solely examining current suitability with land cover, has important implications for white-tailed deer (Odocoileus virginianus) management as challenges such as overabundance and diseases emerge. Our objectives were to develop a process to identify and delineate habitat-type boundaries, determine successional pathways, develop landscape-scale models to quantify deer habitat potential, and describe how habitat-potential models could be used in planning. We delineated habitat-type boundaries and identified successional pathways using digital vegetation and geologic databases and information from the literature for an 8,100-km2 area in northeastern Lower Michigan. We identified deer habitat requirements from the literature; constructed models to quantify fall and winter food, thermal cover, and spring and summer habitat suitability throughout succession; and projected suitability throughout the study area spatially and temporally. Regional differences in habitat types (e.g., poorly drained coniferous types in the northern portion and dry—mesic deciduous or mixed coniferous—deciduous types in the southern portion of the study area) determined regional differences in habitat potential. Generally in the study area, fall and winter food suitability was highest during early (<30 years)- and mid-successional stages (30–100 years), thermal-cover suitability was highest in middle stages, and spring and summer habitat suitability was highest in early stages. The process presented can help managers define wildlife management goals through an understanding of landscape composition, the spatial arrangement and successional changes of habitat types, and their relationship to populations.

Survival and Space Use of Fawn White-Tailed Deer in Southern Michigan

ABSTRACT Many cervids exhibit similar behavior near and following parturition. For example, during their first 2 mo of life, fawn white-tailed deer (Odocoileus virginianus) are relatively sedentary, may be at their highest risk for mortality and are not yet functional ruminants. Relatively few studies describe demographics or space use of fawn white-tailed deer ≤2 mo old despite the potential for mortality through this time period having a relatively large influence on deer population dynamics. Our objectives were to estimate survival, assess cause-specific mortality and describe space use (i.e., cover) of fawn white-tailed deer in an agro-forest ecosystem in south central Michigan. We captured (mid-May to mid-Jun.), radiomarked and monitored 34 fawns during 2004–2006 and pooled data for analyses. Two- and 6-mo survival estimates (Mayfield method) were 81% and 67%, respectively, and canids caused most mortalities during both time periods. Kernel home ranges (95%) during the first 2 mo averaged 40.9 ha (range  =  2.7–166.8), with conifers and lowland deciduous forests selected in proportions higher than available on the study area.

Effects of simulated ungulate browsing on aspen characteristics and nutritional qualities

Natural resource managers in Michigan were concerned about the effects of ungulate browsing on forest stand regeneration. Consequently, we investigated the effects of ungulate browsing on aspen (Populus sp.) stand characteristics and nutritional qualities with simulated browsing experiments in the Pigeon River Country State Forest (Pigeon River Forest) in Michigan from 1985 to 1987

Incorporating estimates of group size in sightability models for wildlife

Abstract Sightability models have been used to estimate population size of many wildlife species; however, a limitation of these models is an assumption that groups of animals observed and counted during aerial surveys are enumerated completely. Replacing these unknown counts with maximum observed counts, as is typically done, produces population size estimates that are negatively biased. This bias can be substantial depending on the degree of undercounting occurring. We first investigated a method-of-moments estimator of group sizes. We then defined a population size estimator using the method-of-moments estimator of group sizes in place of maximum counts in the traditional sightability models, thereby correcting for bias associated with undercounting group size. We also provide associated equations for calculating the variance of our estimator. This estimator is an improvement over existing sightability model techniques because it significantly reduces bias, and variance estimates provide near nominal confidence interval coverage. The data needed for this estimator can be easily collected and implemented by wildlife managers with a field crew of only 3 individuals and little additional flight or personnel time beyond the normal requirements for developing sightability models.

Assessing spatiotemporal changes in tiger habitat across different land management regimes

Human-induced habitat loss and degradation are increasing the extinction probability of many wildlife species worldwide, thus protecting habitat is crucial. The habitat of thousands of imperiled wildlife species occurs in a variety of land management regimes (e.g., protected areas, multiple-use areas), each exerting differing effects. We used the globally endangered tiger (Panthera tigris) to examine the relationships between habitat change and land management in Nepals Chitwan district, a global biodiversity hotspot. We evaluated the effects of environmental and human factors on tiger habitat based on data acquired by motion-detecting cameras and space-borne imaging sensors. Spatiotemporal habitat dynamics in Chitwan National Park and a multiple-use area outside the park were then evaluated in three time periods (1989, 1999, and 2009). Our results indicate that tigers preferred areas with more grasslands and higher landscape connectivity. The area of highly suitable habitat decreased inside the park over the entire 20 year interval, while outside the park habitat suitability increased, especially from 1999 to 2009. The loss of highly suitable habitat inside the park may be associated with an increasing trend of unauthorized resource extraction by a rapidly growing human population, coupled with natural processes such as flooding and forest succession. In contrast, community-based management of natural resources and the prohibition of livestock grazing since the late 1990s likely improved tiger habitat suitability outside the park. Results of this study are useful for evaluating habitat change and guiding conservation actions across the tiger range, which spans 13 countries. Moreover, quantitatively assessing habitat change across different land management regimes in human-dominated areas provides insights for conserving habitat of other imperiled wildlife species around the world.