Erwin E. Klaas

RESOURCE USE AND BEHAVIOR OF MIGRATING SNOW GEESE1

Time-activity budgets for fall-migrating lesser snow geese (Anser caerulescens) were studied at DeSoto National Wildlife Refuge (NWR) during 1976-77. Temperature, wind speed and direction, time of day, seasonal period, and habitat type significantly affected time spent in various activities. Geese spent about 13% of each 24-hour day feeding, primarily on waste corn. Feeding was most intense in early morning and late afternoon. Differences in feeding activity among seasonal periods were evidently caused by changes in weather conditions, food availability, and goose population size. Less than half of an esti- mated 500 metric tons of corn required by the geese during fall was potentially available within refuge boundaries. Although ample corn was available within 8 km of the refuge, fall harvest and plowing caused large seasonal fluctuations in availability of waste corn.

Survey Methods for Assessing Land Cover Map Accuracy

The increasing availability of digital photographic materials has fueled efforts by agencies and organizations to generate land cover maps for states, regions, and the United States as a whole. Regardless of the information sources and classification methods used, land cover maps are subject to numerous sources of error. In order to understand the quality of the information contained in these maps, it is desirable to generate statistically valid estimates of accuracy rates describing misclassification errors. We explored a full sample survey framework for creating accuracy assessment study designs that balance statistical and operational considerations in relation to study objectives for a regional assessment of GAP land cover maps. We focused not only on appropriate sample designs and estimation approaches, but on aspects of the data collection process, such as gaining cooperation of land owners and using pixel clusters as an observation unit. The approach was tested in a pilot study to assess the accuracy of Iowa GAP land cover maps. A stratified two-stage cluster sampling design addressed sample size requirements for land covers and the need for geographic spread while minimizing operational effort. Recruitment methods used for private land owners yielded high response rates, minimizing a source of nonresponse error. Collecting data for a 9-pixel cluster centered on the sampled pixel was simple to implement, and provided better information on rarer vegetation classes as well as substantial gains in precision relative to observing data at a single-pixel.

Wild turkey poult survival in southcentral Iowa

Poult survival is key to understanding annual change in wild turkey (Meleagris gallopavo) populations. Survival of eastern wild turkey poults (M. g. silvestris) 0-4 weeks posthatch was studied in southcentral Iowa during 1994-97. Survival estimates of poults were calculated based on biweekly flush counts and daily locations acquired via radiotelemetry. Poult survival averaged 0.52 ± 0.14% (x ± SE) for telemetry counts and 0.40 ± 0.15 for flush counts No within-vear or across-vear differences were detected between estimation techniques More than 72% (n - 32) of documented poult mortality occurred ≤14 days posthatch and mainmalian predation accounted for 92.9% of documented mortality. If mortality agents are not of concern e suggest biologists conduct 4-week flush counts to obtain poult survival estimates for use in population models and development of harvest recommendations.

Evaluation of transmitter attachment techniques on growth of wild turkey poults

We compared the effects on growth of backpack-mounted and surgically implanted radiotransmitters used as marking techniques in studies of wild turkey (Meleagris gallopavo) poult survival. We applied repeated-measures analysis of variance (ANOVA) and Bayesian analysis to evaluate the null hypothesis that marking technique did not affect growth. Growth in body mass was similar among treatment groups. We did, however, find differences in wing-growth rates among treatment groups. The control group had the highest wing-growth rate, the backpack group had the lowest growth rate, and the surgical implant group was intermediate. Latex backpack harnesses also caused physical developmental problems that would have negatively biased wild poult survival estimates in the field. Surgically implanted transmitters affected wing growth less than the backpack harnesses and are therefore recommended for attaching transmitters to wild turkey poults.

Factors influencing wild turkey hen survival in southcentral Iowa

A decline in the population of eastern wild turkeys (Meleagris gallopavo silvestris) in southcentral Iowa necessitated more current estimates of population parameters. Survival of 126 eastern wild turkey hens in southcentral Iowa was investigated during 1993-96. Estimates of annual survival averaged 0.676 ± 0.048% (x ± SE) for adults and 0.713 ± 0.125 for subadults. Mammalian predators, primarily coyotes (Canis latrans) and red fox (Vulpes fulva) accounted for 64% of all documented mortality. Age-specific annual survival distributions differed within years (P < 0.03), but no difference was detected in survival between age classes across years (P = 0.49). Based on chronological dates, survival of adult hens differed among seasons across years (P = 0.03). However, seasonal survival was not different when estimates were based on hen behavior (P = 0.48) Risk of mortality for hens increased by 2.0% for every 100-m increase in dispersal distance, decreased by 2.0% for every 10-ha increase in home range size, and decreased by 3.5% for each 1.0% increase in proportion of home range in woody cover. Although the exact cause of the population decline remains unknown, we sugges it was more likely related to a decrease in production than changes in hen survival. Declining turkey populations would likely benefit more from management designed to increase reproduction rather than hen survival.

A method for sampling waste corn

De nombreux animaux (cervides, faisans, etc.) se nourrissent sur les grains laisses sur le sol apres la recolte. Il est interessant de comparer la disponibilite de cette nourriture et de la mesurer pour des champs exploites par diverses techniques

Organochlorine residues, eggshell thickness, and nest success in barn owls from the Chesapeake Bay

Eggs of barn owls (Tyto alba) were collected from 18 nests in offshore duck blinds on the Maryland side of the lower Potomac River estuary in 1972 and 1973 and analyzed for organochlorine residues. DDE was found in 100% of the clutches, PCBs in 89%, and dieldrin in 78%. Eggshell thickness was inversely correlated with concentrations of DDE, DDD, and dieldrin residues. Six of the 18 clutches had mean DDE residues above 5 ppm, and eggshell thickness in these six clutches was significantly less (P<0.001) than in the other 12 clutches. The owls produced 1.7 young per active nest in 1973. This rate is slightly below the reproductive rate needed to maintain a stable population. An estimated 15% of the population carried concentrations of organochlorine residues that may have been detrimental to their reproduction. Passerine birds, taken extensively as food by a small proportion of the population, are believed to have been the source of elevated concentrations of organochlorines in these barn owls.

Patterns of artificial nest depredation in a large floodplain forest.

We used artificial bird nests to examine the relative effects of local habitat features and the surrounding landscape on the probability of songbird nest depredation in floodplain forests of the Upper Mississippi River. We found that the probability of depredation increased with size of floodplain forest plots. In small plots, the probability of depredation tended to increase away from the forest edge. Small patches of floodplain forest within a large river system can provide valuable nesting habitat for songbirds. We suggest that depredation pressure may be lower due to isolation effects. The probability of nest depredation increased with increasing canopy cover surrounding the nest tree and decreasing cover around the nest. Managers seeking to discourage nest predators in floodplain forests should consider managing for habitats that supply dense cover for nest concealment and an open tree canopy. JOURNAL OF WILDLIFE MANAGEMENT 64(2):576-583

Organochlorine residues and eggshell thinning in anhingas and waders

Residues of organochlorine compounds occur commonly in environmental samples and have been associated with adverse effects in numerous avian species (Cooke 1973; L. F. Stickel 1973; W. H. Stickel 1975; Ohlendorf et al. 1977; H. M. Ohlendorf, R. W. Risebrough, and K. Vermeer, unpublished manuscript). The affected species are usually terminal consumers, generally those feeding on aquatic organisms (primarily fish) or birds.

Conservation, Restoration, and Management of Great Plains Landscapes

The settlement and domestication of the Great Plains is essentially complete. The most spectacular large mammal concentrations on the continent have been almost entirely destroyed. In the span of about four human generations, the Plains’s former inhabitants have been conquered and the landscape greatly changed. Relative to the western mountains and deserts, the Great Plains has almost no large wilderness areas and relatively little publicly owned land exists. Of these, the largest tracts are in designated national grasslands that are managed chiefly for livestock grazing. The tallgrass prairie has been largely replaced with row crop agriculture, transportation corridors, and urban development. Wetlands in the Prairie Pothole region have been drained and put into agricultural production. Much of the shortgrass prairie in the western half of the region is still intact, but the native mammals have been replaced with cattle and other livestock. But, even on the High Plains where rainfall is low, irrigation has allowed large areas of grassland to be plowed and converted to grain crop production.