Treesearch

We measured the costs of Brown-headed Cowbird (Molothrus ater) parasitism incurred by Field Sparrows (Spizella pusilla) and Indigo Buntings (Passerina cyanea). We predicted that the frequent occurrence of nest desertion as a response to cowbird parasitism in Field Sparrows would be reflected by a higher cost of parasitism for that species. We also compared growth and survival of cowbird nestlings between hosts, predicting that they would do poorly at Field Sparrow nests because the latter appear to be avoided by cowbirds. Both species experienced reduced body mass gain in parasitized...

Size of a forest patch is a useful predictor of density and reproductive success of Neotropical migratory birds in much of eastern North America. Within these forested landscapes, large forest tracts appear to be sources-fragments in which surpluses of offspring are produced and can potentially colonize new fragments including woodlot sinks where reproduction fails to balance adult mortality. Within agricultural landscapes of the midwestern U.S., where forests are severely fragmented, high levels of brood parasitism by brown-headed cowbirds (Molothrus ater) and intense predation on nests...

The swamp rabbit (Sylvilagus aquaticus) is one of the least studied North American lagomorphs; a better understanding of the habitat types it uses will improve management of this species. We studied microhabitat characteristics of sites associated with specific behaviors of the swamp rabbit. During spring-summer (15 April-1 October) and fall-winter (1 October-15 April) we examined sites used by rabbits for fecal deposition, browsing, and daytime resting. Sites were located in 3 different macrohabitats (mixed pine-hardwood upland forest, mature bottomland forest, and cut-over bottomland...

Efforts to restore floodplains are complicated by our variable understanding of history and ecology; our lack of knowledge of past environmental and vegetative conditions; and our differing viewpoints of what natural, what the role of humans is in the ecosystem, and what the desirable restored state is. Managers are challenged to decide how to restore native vegetation and hydrologic regimes in the Mississippi and Missouri River floodplains because they are among the most altered ecosystems in North America.

As the population of the United States increases and new development sprawls out across the landscape, ecosystems are greatly impacted. Sprawl and the competition for undeveloped land outside urban areas makes it especiaily important that we make the most effective use of the existing bank of reserved open space. Meeting goals of ecological health and connectivity at the same time that undeveloped lands are being converted to urban areas means that we have to pay closer attention to the integrity of natural areas within the urban system. Restoration is one of the best means that we have...

Indigo Buntings (Passerina cyanea) nesting in old-field habitats in central Missouri are parasitized at least four times as often as Field Sparrows. I used model cowbirds placed near nests to test if host aggression explained this difference. Although both Field Sparrows and Indigo Buntings responded to Brown-headed Cowbird models with significantly more chips than to a Fox Sparrow (Passerella iliaca) control, only one female Field Sparrow and one Indigo Bunting pair attacked the cowbird model. Because the utility of aggression and cowbird recognition may depend on a host's actually...

Two strains of the wheat stem rust fungus, Puccinia graminis f. sp. tritici, were crossed on barberry, and a single F1 progeny strain was seifed. The parents, F1 and 81 F2 progeny were examined for virulence phenotypes on wheat differential cultivars carrying stem rust resistance (Sr) genes. For eight Sr differentials phenotypic ratios are suggestive of single dominate avirulence genes AvrT8a, AveT9a, AvrT10, AvrT21, AvrT28, AvrT30, and AvrTU. Avirulence on the Sr. (Sr 'fleck') differential showed phenotypic ratios of approximately 15:1, indicating epistatic interaction of two genes...

In an open-ended, written survey, I asked residents and visitors of the Black River area in northern Michigan to identify and describe places that were special to them. I conducted a thematic interpretation of the responses, using a set of indexing and cross-referencing marcos that I wrote in Word Perfect 5.1. The themes that emerged included the natural beauty ofthe area, its quiet and uncrowded character, the history of the harbor and fishing community, and the high quality of recreation facilities. The Ottawa National Forest used this information in developing a plan for future managemen...

Volume and percent ground cover of down wood were estimated on the MOFEP sites from two separate sampling inventories, line transects and fixed-area plots. Line transects were used to sample down wood in the 1990-91 and 1994-95 inventories and fixed-area plots were used in an additional inventory in 1995. Line transect inventories estimated a range in ground cover from 1.2 to 2.9 percent in 1990-91 and from 1.0 to 2.2 percent in 1994-95. Fixed-area plots estimated a range in ground cover from 0.6 to 1.7 percent. Percent ground cover estimated by line transects was significantly higher than...

In April 1996 an exciting new project was announced, an unprecedented conservation undertaking in one of the nation's most densely populated regions. Chicago Wilderness is a collaborative effort among the more than 90 organizations that make up the Chicago Region Biodiversity Council (CRBC) to protect, restore, and manage the region's natural landscapes while educating the public about the value of these lands and management activities. A central goal of Chicago Wilderness is the ecological restoration of landscapes that are considered degraded and no longer representative of their...