James J. Dinsmore

LOCAL AND LANDSCAPE-LEVEL INFLUENCES ON WETLAND BIRD COMMUNITIES OF THE PRAIRIE POTHOLE REGION OF IOWA, USA

Bird species richness and individual species densities were measured in wetland complexes in 1998. These values were then related to habitat variables within the complexes and to area of wetland habitat in the surrounding landscape. The percentage of wetland area within a complex that was covered with emergent vegetation and the total area of wetland habitat in the 3 km surrounding each complex were significant predictors of species richness. A perimeter-to-area ratio was the most frequently selected variable for inclusion in species-density models, being selected for 8 of 15 models. Five species’ densities were related to the percentage of the wetland area that was covered by emergent vegetation, and 4 densities were related to the area covered by weak-stemmed wet-meadow vegetation. Densities of 5 species, as well as the overall species richness, were associated with a measure of the amount of wetland habitat within a 3-km buffer surrounding the wetland complexes. This indicates that the presence and abundance of some wetland bird species may be influenced by the amount of wetland habitat nearby. Thus, programs that encourage restoration of tracts of land that contain multiple wetland basins should be emphasized to maximize benefits to the wetland bird community.

A Review and Synthesis of Habitat Use by Breeding Birds in Agricultural Landscapes of Iowa

Existing information on bird species composition, abundance and nesting sta- tus during the breeding season (May through July) was compiled for habitats characteristic of the agricultural landscapes of Iowa. Data were derived from 60 sources for 144 bird species in 20 habitats. Total numbers of breeding bird species were highest in floodplain forest (107 species) and upland forest (85), and lowest in small grains (31) and herbaceous fencerows (27). Species abundances were standardized and categorized on a scale from 0 (absent) through 5 (very abundant with >250 individual birds/census count/100 ha). Bird species abundances are lowest in some agricultural habitats (e.g., tilled row crops and small grains) and highest in narrow, strip-cover habitats (e.g., railroad rights-of-way, wooded fencerows and farmstead shelterbelts). Species abundance patterns in natural habitats (forest, marsh and prairie) are intermediate between those in agricultural and strip-cover habitats. Twenty-five species occurred only in forest habitats and 14 only in marshes. Other species selectively (through not exclusively) use tilled row crop, grassland or wooded habitats. Principal com- ponents analysis was used to assess the relative similarities in use of the 20 habitats by the assemblage of breeding birds in Iowa. Predicted numbers of nesting species increased from 18 to 93 over four landscape scenarios representing a progression from an intensively farmed row-crop monoculture to a diverse mosaic of crop and noncrop habitats. Although laborious, the approach developed in our study has been useful for standardizing and synthesizing a diverse literature in efforts to conduct ecological risk assessments for farmland birds. It can also provide valuable baseline data for landscape-level research.

Breeding bird communities of recently restored and natural prairie potholes

We compared the breeding bird communities of natural and recently restored prairie potholes in northern Iowa in 1989 and 1990. Species richness of breeding birds was higher (P<0.05) at natural wetlands, although duck pair counts and species richness were not significantly different between wetland types (P>0.1). Common yellowthroat (Geothlypis trichas), red-winged blackbird (Agelaius phoeniceus), marsh wren (Cistothorus palustris), and swamp sparrow (Melospiza georgiana) were each more abundant at natural than at restored wetlands during at least one year (P<0.05). Brown-headed cowbirds (Molothrus ater) parasitized a significantly greater proportion of red-winged blackbird nests at natural than at restored wetlands. Incomplete development of typical vegetation structure evidently depresses bird species richness at recently restored prairie potholes. Drought the year before and during the first year of our study undoubtedly affected our results. Similar studies should be conducted during periods of relatively high precipitation to complement our results.

Influence of wetland age on bird use of restored wetlands in Iowa

A goal of wetland restoration is to provide habitat for breeding populations of waterfowl and other bird species. To meet this goal, it is important to determine how birds respond to restored wetlands and which factors influence their use of restored wetlands. We examined the relationship between bird species richness and years since restoration at restored prairie wetlands in lowa. We detected 42 bird species in restored wetlands. 15 of which were breeding species. The mean number of breeding bird species was significantly greater in older restored wetlands (4.3 species in 1-year-old wetlands, 7.2 species in 4-year-old wetlands,p=0.005). The mean number of all bird species, waterfowl species, and breeding waterfowl species did not change with wetland age. Total and breeding bird species richness increased with percent cover of emergent vegetation. Waterfowl species richness and breeding waterfowl species richness were influenced more by wetland area than vegetation characteristics, whereas total species richness and breeding bird species richness were influenced more by vegetation characteristics. If the goal of restoration is simply to provide a breeding site for waterfowl, our data suggest that this can be done in a few years. However, we favor longterm restorations. Such restorations are more likely to have a more diverse bird community that more closely resembles those found in natural wetlands.

Factors affecting egg predation by american crows

We studied predation by breeding American crows (Corvus brachyrhynchos) on artificial duck nests in upland and overwater habitats from April to July in 1986 and 1987 in the prairie pothole region of southwestern Manitoba, Canada. Predation was higher on nests placed within home ranges of breeding crows than on nests placed at random locations outside of home ranges. However, artificial nests placed >700 m from crow nests, yet within home ranges, were relatively safe from predation. Predation was greater on upland than on overwater nests. Nests in low vegetation were most vulnerable to crows, but increases in cover height above 20-50 cm did not substantially reduce predation. J. WILDL. MANAGE. 54(3):433-437 The possibility that egg predation has depressed waterfowl nesting success throughout the prairie pothole region (Cowardin et al. 1985, Greenwood et al. 1987) is of concern to waterfowl managers because this region is an important breeding area (Smith et al. 1964, Batt et al. 1989). Increasing nest success in the prairie pothole region is a goal of the North American Waterfowl Management Plan (Can. Wildl. Serv. and U.S. Fish Wildl. Serv. 1986). Electric fences are sometimes used to exclude predators from habitat managed for nesting waterfowl (Lokemoen et al. 1982). However, these fences cannot exclude avian species such as American crows, which are recognized as important predators of waterfowl eggs (e.g., Kalmbach 1937, Johnson et al. 1989). Egg predation by crows seldom has been investigated in detail, yet such data are needed to improve waterfowl management decisions in areas where crows are potential predators. Sugden and Beyersbergen (1986, 1987) found that crows that searched on foot located more artificial nests when nests were clumped rather than dispersed and were located in vegetation short and sparse rather than tall and dense. We compared rates of predation by crows on artificial duck nests: (1) during different stages of crow nesting cycles, (2) in upland and overwater sites, (3) in different vegetation types, (4) within and outside breeding crow home ranges, (5) at varying distances from active crow nests, and (6) in different heights of vegetation. Our study was not designed to estimate predation rates on wild duck nests. Rather, we used artificial nests as a tool to examine how nest site characteristics affected predation rates by crows, but Gdtmark et al. (1990) showed that predation rates on artificial and natural nests can be similar. This project was funded by the North American Wildlife Foundation through the Delta Waterfowl and Wetlands Research Station, and Iowa State University through the Department of Animal Ecology and the Iowa Agriculture and Home Economics Experiment Station. We thank J. M. Buenger, R. J. Keith, and D. M. Richardson for assistance in collecting data, and D. C. Glenn-Lewin, R. J. Greenwood, D. H. Johnson, E. E. Klaas, and L. G. Sugden for providing critical comments on the manuscript. M. G. Anderson, A. B. Sargeant, and L. G. Sugden provided valuable insight during the formative stages of the study. This is Journal Paper J-13149 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, Project 2466.

Status, Habitat Use, and Management of Red-Shouldered Hawks in Iowa

In recent years the red-shouldered hawk (Buteo lineatus) has declined in numbers in Iowa (Brown 1964, Koenig 1975) and nationwide (Cohen 1970:14, 36; Brown 1971; Hackman and Henny 1971). In the Midwest, it is listed as rare or endangered in Illinois, Iowa, Michigan, Missouri, and Wisconsin (Roosa 1977, Merz 1978). The decline probably is due directly or indirectly to habitat alteration (Todd 1940, Cohen 1970, Henny et al. 1973, Oberholser 1974, Portnoy 1974, Campbell 1975, Bock and Lepthien 1976). The objectives of this study were to systematically survey potential redshouldered hawk nesting habitat in Iowa using a land-use data base, and to provide information on habitat use and management recommendations.

Responses of Plants and Arthropods to Burning and Disking of Riparian Habitats

Abstract Alteration of Iowa, USA, landscapes for agricultural production has resulted in a loss of >99% of the original prairie and >95% of native wetlands. This conversion has included riparian areas, which, as interfaces between terrestrial and aquatic ecosystems, are important to many wildlife species. Farm Bill programs have resulted in the reestablishment of millions of hectares of grasslands and wetlands nationwide, including >100,000 ha in riparian areas of the Midwest. We assessed plant and arthropod responses to burning and disking of riparian grasslands in east-central Iowa in 2001 and 2002. Burning altered the plant community by removing litter and standing dead vegetation and had negative effects on several arthropod taxa, including Hemiptera and Lepidoptera. However, we observed no differences in vegetation or arthropods between burned and unburned fields during the second year postburning (P > 0.05). Disking decreased the cover of grasses, litter, and standing dead vegetation and increased plant species richness and the cover of forbs and bare ground (P < 0.05). Arthropod abundance and dry biomass were greater on disked than undisked portions of fields (P < 0.05). Increases in the abundance and biomass of arthropods associated with changes in vegetation structure and composition likely improved habitat quality for a number of breeding bird species. Both burning and disking appear to be effective management options for maintaining or enhancing riparian grasslands for wildlife.

Habitat islands and the equilibrium theory of island biogeography: testing some predictions

SummarySpecies-area data from a study of marsh birds are used to test five predictions generated by the equilibrium theory of island biogeography. Three predictions are supported: we found a significant species-area relationship, a non-zero level of turnover, and a variance-mean ratio of 0.5. One prediction is rejected: the extinction rates were not greater on small islands. The results of one test are equivocal: the number of species on each island was not always the same. As Gilbert (1980) suggests, a strong species-area relationship alone does not validate the theory. The avian communities we studied were on habitat islands, not true islands, and underwent complete extinction annually. Thus caution must be used before applying the theory to these and other habitat islands.

An Assessment of Coyote and Dog Predation on Sheep in Southern Iowa

A questionnaire survey, field necropsies, domestic-animal claims, and a postcard survey were used to assess coyote and dog predation on sheep in southern Iowa. Forty-one percent of 1,251 questionnaire respondents reported they had sheep killed by dogs or coyotes (Canis latrans) during 1975. Of the total losses reported, 41% were attributed to predation, 30% to disease, and 13% to unknown causes. Three percent of all sheep owned by the questionnaire respondents allegedly were killed by coyotes, and 1% were killed by dogs. Both field necropsies and domestic animal claims showed that dogs killed more sheep per incident and sheep per operator than did coyotes. Almost 60% of the postcard respondents attributed sheep losses to predation during 1976 and 1977. Coyote predation varied during summer and fall, with 80% of the incidents occurring from 1 May to 1 October; dog predation did not follow a distinct chronological pattern. Field necropsies of 227 alleged predator-caused sheep losses revealed that sheep producers correctly assessed the cause more than 94% of the time. The results of the questionnaire and postcard surveys were similar. Domestic-animal claims underestimated the actual number of losses that occurred. J. WILDL. MANAGE. 45(4):883-893 Intensive predator control measures implemented by early settlers drastically reduced the number of coyotes in Iowa (Van Hyning and Pellett 1910, Scott 1937, Bowles 1975). During the past 20 years, however, the coyote population in Iowa and the incidence of reports of livestock losses due to coyote predation have increased considerably (Boggess 1975, Bowles 1975, Andrews and Boggess 1978). Concurrently, fur prices have increased dramatically (Andrews and Boggess 1978), making the coyote an important resource for hunters and trappers. Boggess et al. (1978) found that, since 1970, alleged sheep losses caused by dog predation have decreased at about the same rate that losses due to coyote predation have increased. This suggests that coyotes may be blamed for some losses actually caused by dogs (Denney 1974). Recent field studies (Henne 1975; McAdoo 1975; DeLorenzo and Howard, unpubl. rep., U.S. Fish and Wildl. Serv., Denver, Colo., 1976; Nesse et al. 1976; Nass 1977; Tigner and Larson 1977) and surveys (Nielson and Curle 1970; Reynolds and Gustad, unpubl. rep., U.S. Fish and Wildl. Serv., Denver, Colo., 1971; Early et al. 1974; Meduna and Robel, unpubl. data, 1976; Nesse et al. 1976; Gee et al. 1977) have explored the impact of coyote predation on the sheep industry in western states. However, similar research has been needed in the midwestern farm states, where livestock husbandry practices, habitat, dog and coyote densities, and predator control methods are quite different from those in the West. Before implementation of a management plan for the coyote in Iowa, the extent of sheep losses and the factors influencing losses caused by coyotes and dogs needed to be assessed. We are grateful to all who assisted in this project. H. Bal, R. Bishop, R. Coffey, W. Downing, A. Farris, W. Franklin, J. Heer, E. Johnson, E. Klaas, M. Ryan, R. 1 Joint contribution: Iowa Conservation Commission Federal Aid to Wildlife Restoration Project W115-R-4 and 5, and Journal Paper J-9778 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, Project 2031. J. Wildl. Manage. 45(4):1981 883 This content downloaded from 157.55.39.159 on Sun, 18 Sep 2016 06:02:57 UTC All use subject to http://about.jstor.org/terms 884 COYOTE AND DOG PREDATION ON SHEEP* Schaefer et al. Schaefer, C. Steffen, T. Wickersham, L. Wing, and A. Wywialowski provided valuable criticism throughout the study and preparation of the manuscript. J. Prescott, C. Roberg, and R. Sayles assisted in data coding, and H. Cook, J. Kienzler, and V. Wright were extremely helpful with the questionnaire design and data analysis. We also thank the coyote hunters, trappers, and sheep producers in southern Iowa for their cooperation.

Short-term Effects of Burning and Disking on Songbird Use of Floodplain Conservation Easements

Abstract Extensive conversion of Midwestern riparian areas for agricultural production has had many consequences including reduced habitat for nesting birds. However, more than 120,000 ha of riparian habitat have been restored in this region through USDA conservation programs. In 2001 and 2002, we assessed songbird responses to burning and disking for management of conservation easements in east-central Iowa. We randomly assigned herbaceous riparian fields to burning and disking treatments and collected data on density and species richness of songbirds in these habitats. Total density of grassland and wetland species and red-winged blackbirds (Agelaius phoeniceus) were reduced by burning in the first and second breeding seasons after burning; common yellowthroat (Geothlypis trichas) density decreased with burning only in the first season. Disking led to increased density of grassland and wetland birds and greater overall avian conservation value on treated relative to untreated fields in the year after treatment. Changes associated with burning and disking treatments were likely related to changes in both vegetation structure and abundance of arthropod food resources. Despite decreased bird densities with burning, fire is a necessary management tool to control woody vegetation. Overall, both burning and disking appear to be effective management practices for maintaining herbaceous riparian habitats for grassland birds.