Ernie P. Wiggers

Demographic factors contributing to high raccoon densities in urban landscapes

We simultaneously studied raccoon (Procyon lotor) populations inhabiting urban, suburban, and rural open areas in northeastern Illinois, USA, to examine the effects of urbanization on raccoon demographics. We predicted that raccoon density was higher in urbanized than rural landscapes because of increased survival and reproduction rates and greater site fidelity in urbanized areas. Density estimates for both the urban and suburban sites were greater (P < 0.001) than for the rural site during all seasons. Density estimates for the urban and suburban sites were similar (0.177 ≤ P< 0.603) during 4 of seasons. Percentages of porous females were similar among sites. However, higher proportions of juveniles to adult females captured at the urbanized sites may indicate larger litter sizes. Adult female survival was highest at the urban site during the first 2 years, but dropped due to an unknown disease during the final year. Urban raccoons experienced the fewest mortality sources, whereas rural raccoons experienced the most. Disease was the greatest mortality factor at the urban site, while vehicle-related mortalities dominated at the suburban and rural sites. The high ratio of marked to unmarked raccoons captured may indicate greater site fidelity at urbanized sites. Our data suggest that multiple factors, including increased survival, higher annual recruitment, and increased site fidelity, are jointly responsible for high-density raccoon populations in urbanized areas. Direct management of raccoon numbers in urbanized areas likely will require continuous control measures, because raccoons are capable of quickly repopulating an area after the resident population has been reduced. The most effective control measure may be the reduction of anthropogenic food sources that support raccoons at high densities.

Seasonal movements and habitat use of female white-tailed deer associated with an urban park

Many cities throughout the United States have implemented programs for managing white-tailed deer (Odocoileus virginianus) populations. However, basic ecological questions, such as seasonal movement patterns and habitat use of deer in urban landscapes, have gone relatively unstudied. We conducted a telemetry study to investigate seasonal movements and habitat use of female white-tailed deer in Bloomington, Minnesota, USA, during 1996-1999. Home range size varied seasonally, with the largest occurring during the spring (x = 144 ha [SD = 7 ha]) and smallest during the summer (x = 50 ha [SD = 7 ha]). Home ranges during fall (x = 93 ha [SD = 11 ha]) and winter (x = 85 ha [SD = 6 ha] ) were similar in size. Deer in this study demonstrated a high degree of fidelity with their seasonal home ranges, except during a severe winter when 75% of the deer shifted their fall home range. These deer all returned to their original home range the following spring. Habitat analysis indicated that deer used woody cover habitats during every season. Habitats within parks and conservation areas made up the greatest percentage (52-68%) of home range compositions during all seasons except the severe winter when 78% of the home range encompassed residential neighborhoods. Our data suggest that a major difference between urban and rural deer is in spatial scale. Deer in this study used habitats that might be expected based on studies of deer in rural landscapes but occupied smaller home ranges than normally reported for deer in rural landscapes. Deer management programs developed for urban communities should consider movement patterns of deer to ensure the most effective control of particular nuisance individuals.

Habitat Selection and Breeding Status of Swainson's Warblers in Southern Missouri

Habitat selection and productivity are poorly documented for the Swainsons warbler (Limnothlypis swainsonii) throughout its breeding range. In southern Missouri in 1992-93, we quantified and compared habitat structure of occupied and unoccupied canebrakes (Arundinaria gigantea) and monitored nests to determine productivity. Twenty-nine of 100 canebrakes searched in 1992 were occupied by Swainsons warblers. Occupied canebrakes (n = 29) had higher cane density (P = 0.009), lower canopy (P = 0.018) and sub-canopy height (P = 0.008), and less herbaceous ground cover (P = 0.003) than did unoccupied canebrakes (n = 30). In 1993, we compared 16 additional occupied sites with 15 new unoccupied sites. Cane height (P = 0.030), tree diameter at breast height (dbh) (P = 0.006), and percent herbaceous cover (P = 0.001) were higher in occupied than in unoccupied canebrakes, whereas percent leaf litter was lower (P = 0.011). Using the 1992 data, we developed a linear logistic regression model to predict the probability of Swainsons warbler occurrence. Applied to the 1993 data, this model correctly predicted only 3 of 16 occupied and 8 of 15 unoccupied canebrakes. We then pooled the data and developed a new model that correctly predicted 31 of 45 occupied and 35 of 45 unoccupied canebrakes. Clutch size averaged 3.65 eggs/nest (n = 17) and nest production was 2.12 fledglings/nest. We failed to identify consistent distinctions between occupied and unoccupied canebrakes, and reproductive success was within the range reported for this and similar species. Therefore, based upon our results, we found no evidence that suitable habitat limited Swainsons warbler abundance in Missouri.

Nest-site characterization and reproductive success of Mississippi kites in the Mississippi river floodplains

The Mississippi kite (Ictinia mississippiensis) is considered rare in Missouri and occupies a habitat in the state that is being fragmented and converted into unsuitable habitat. To enhance our understanding of its habitat requirements and population status e examined the characteristics of Mississippi kite nesting habitat and reproductive success at 33 nest and random sites in 1990 and 26 sites in 1991 in the floodplain forests along the Mississippi River in southeastern Missouri. Forest tracts containing Mississippi kite nests (n = 7) were larger (x = 683 ha) than randomly sampled forest tracts (x = 7 ha, n = 7). Trees containing nests were taller than trees at random, and nests were positioned within the tree so that nests were above the surrounding forest canopy. Overstory and midstory tree diameter at breast height (dbh) were greater at nest sites than at random sites. Overstory tree density was less at nest sites than at random sites. Eastern cottonwood (Populus deltoides), American sycamore (Platanus occidentalis), and shagbark hickory (Carya ovata) were the most common trees at nest sites, whereas black willow (Salix nigra), green ash (Fraxinus pennsylvanica), and silver maple (Acer saccharium) were more frequent at random sites. The modified Mayfield nest-success estimate for 10 successful and 14 failed nests was 22%. We conclude that Mississippi kites select patches of atypically tall trees surrounding an even taller nest tree for nesting sites within the Mississippi River floodplain forests in southeastern Missouri. Preserving the larger forest tracts in the region, particularly those currently used as nest sitcs, and assuring the sustainability of the tallest growing trees like cottonwoods would have ong lasting, positive effects on Mississippi kite habitat in this region of its range.

Capturing clapper rails using thermal imaging technology

ABSTRACT Capturing sufficient numbers of marsh birds for telemetry studies is difficult due to the secretive nature and inaccessible habitat of the birds. We experimented with thermal imaging technology to locate clapper rails and subsequently capture them from an airboat in South Carolina tidal marshes. This method produced a capture rate of up to 19.2 rails/hr, which exceeded other capture rates in the literature. We believe this technique will improve capture efficiency for clapper rails, and potentially other secretive marsh birds, enhancing opportunities for studying these important species.

Ecotourism as a revenue-generating activity in South Carolina Lowcountry plantations

The South Carolina lower coastal plain, locally called the Lowcountry, is an area of great ecological diversity with bottomland swamps and coastal marshes. The Lowcountry still contains many large tracts of land, privately owned as ‘plantations’. These plantations tend to be self-supporting and many are seeking additional revenue sources, and ecotourism is developing as one of these sources. Tourism is the backbone of the Lowcountry economy. This study identified the level of existing ecotourism activities supported by Lowcountry plantations and their expectations for the future levels of natural resource-based activities. Ecotourism is blossoming as an income source, but hunting leases and timber harvests are the primary natural resource-based income sources. Owners did express interest in ecotourism activities as a source of future income. A lack of the management and business ability was the main obstacle to expanding ecotourism enterprises.