Stanley A. Temple

Nest Predation and Brood Parasitism of Tallgrass Prairie Birds

Rates of nest predation and brood parasitism on 5 bird species nesting in fragments of tallgrass prairies in Minnesota were affected by the size of the prairie fragment containing the nest, the distance from the nest to a wooded edge, and the number of growing seasons since the vegetation around the nest was last burned. Rates of nest predation for 5 species were lower (P < 0.10 in each case) for nests on large (-130 ha) fragments, in areas far (?45 m) from a wooded edge, and in vegetation that was recently burned (s3 yr). Rates of brood parasitism were lower (P < 0.10 in each case) far from a wooded edge. Prairie management to maximize nest productivity should provide large, regularly burned prairies with no nearby wooded edges. J. WILDL. MANAGE. 54(1):106-111 More than 99% of the presettlement tallgrass prairie in Minnesota has been converted to agriculture and other uses. Remnant tracts of prairie are usually small, isolated parcels surrounded by habitat unsuitable for most prairie birds. Many of the remaining prairie fragments contain invading tree species, such as aspen (Populus tremuloides) and willow (Salix spp.), and/ or cottonwood (Populus deltoides) shelterbelts. Natural fires, once common occurrences in the tallgrass prairie (Daubenmire 1968), are suppressed, but prescribed burning is now a major management activity on native prairies. Several animals that depredate or parasitize nests of prairie birds have recently increased in abundance in western Minnesota. For example, raccoons (Procyon lotor), nest predators once limited to southeastern Minnesota, have expanded their range into the prairie region and are now common (Hazard 1982). Densities of red fox (Vulpes vulpes) have increased due to changes in agricultural practices and the reductions of other canids (Johnson and Sergeant 1977). In addition, brown-headed cowbirds (Molothrus ater), an obligate brood parasite, have greatly increased in abundance since 1900 (Brittingham and Temple 1983). Currently, most management of prairie fragments is undertaken to perpetuate native plant communities, but little is known about how vegetation management affects breeding bird populations on prairies. Consequently, we studied the effects of nest predation and brood parasitism on the productivity of birds nesting in managed tallgrass prairies in western Minne-

DECIDUOUS‐FOREST BIRD COMMUNITIES IN A FRAGMENTED LANDSCAPE DOMINATED BY EXOTIC PINE PLANTATIONS

Impacts of habitat fragmentation on forest bird communities have often been studied in landscapes dominated by agriculture. The striking structural differences between forest fragments and the matrix have led most researchers to rely on island biogeographic theory to predict the distribution of bird species in fragmented forests. However, in some cases the vegetation surrounding fragments is not completely unsuitable for forest birds. Thus, a more general framework is needed to understand the effects of habitat fragmentation. The mosaic approach considers fragments as integrated parts of a complex landscape composed of patches of habitat of different qualities. In the coastal area of the Maule region in central Chile the remaining hualo (Nothofagus glauca) forests cover <10% of the landscape, are severely fragmented, and are imbedded in a matrix of exotic pine plantations. We compared the island and mosaic approaches as explanations for the distribution and abundance of forest birds. Variable circular plo...

Plant-Animal Mutualism: Coevolution with Dodo Leads to Near Extinction of Plant

An endemic sapotaceous tree Calvaria major found on the island of Mauritius is nearly extinct because its seeds apparently required passage through the digestive tract of the now-extinct dodo Raphus cucullatus to overcome persistent seed coat dormancy caused by a specially thickened endocarp.

Some ecological and socio-economic considerations for biomass energy crop production

Abstract Power generation using biomass could provide substantial environmental and socio-economic benefits. Production of the feedstocks to fuel biomass power plants can either add to potential environmental gains or contribute to the environmental problems which the agriculture and forestry industries already face. Likewise, the biomass energy infrastructure can help strengthen agricultural economies or speed the decline of rural communities. The purpose of this paper is to suggest a regional approach to ensure that energy crop production will proceed in an ecologically and economically sustainable way. At this juncture, we have the opportunity to build into the system some ecological and socio-economic values which have not traditionally been considered. If crop species are chosen and sited properly, incorporation of energy crops into our agricultural system could provide extensive wildlife habitat and address soil and water quality concerns, in addition to generating renewable power. We recommend that three types of agricultural land be targeted for perennial biomass energy crops: (1) highly erodible land; (2) wetlands presently converted to agricultural uses; and (3) marginal agricultural land in selected regions. Fitting appropriate species to these lands, biomass crops can be successfully grown on lands not ecologically suited for conventional farming practices, thus providing an environmental benefit in addition to producing an economic return to the land owner.

Methodological problems in studies of avian nest defence

Abstract We examined whether red-winged blackbirds ( Agelaius phoeniceus ) differed in nest defence response to: (1) a live crow ( Corvus brachyrhynchos ) versus a taxidermic mount, (2) different postures of the same human intruder at the nest, and (3) a familiar versus a novel human intruder at the nest. We found that blackbirds were more aggressive: (1) to a mounted than a live crow, (2) to a human being staring at the nest than to a human being gazing at the bird, and (3) to a familiar than to a novel human being. We discuss the implications of our results for avian nest defence studies.

Record-Breaking Early Flowering in the Eastern United States

Flowering times are well-documented indicators of the ecological effects of climate change and are linked to numerous ecosystem processes and trophic interactions. Dozens of studies have shown that flowering times for many spring-flowering plants have become earlier as a result of recent climate change, but it is uncertain if flowering times will continue to advance as temperatures rise. Here, we used long-term flowering records initiated by Henry David Thoreau in 1852 and Aldo Leopold in 1935 to investigate this question. Our analyses demonstrate that record-breaking spring temperatures in 2010 and 2012 in Massachusetts, USA, and 2012 in Wisconsin, USA, resulted in the earliest flowering times in recorded history for dozens of spring-flowering plants of the eastern United States. These dramatic advances in spring flowering were successfully predicted by historical relationships between flowering and spring temperature spanning up to 161 years of ecological change. These results demonstrate that numerous temperate plant species have yet to show obvious signs of physiological constraints on phenological advancement in the face of climate change.

Nest-Defense Behavior of the American Crow in Urban and Rural Areas

The American Crow (Corvus brachyrhynchos) has traditionally been persecuted as a pest and hunted for sport. As recently as 1980 there were an estimated 4,530,000 crow hunter-days in the United States (USDI and USDC 1982a). In recent decades crows, which in the past were typically rural birds, have begun nesting in cities where ordinances prohibit the discharge of firearms. As a result of this colonization of urban areas, two adjacent crow populations exist in many regions, a persecuted rural one and a protected urban one. We took advantage of this situation to examine how the nest-defense behavior of crows has been modified by the presence or absence of persecution. We examined two complementary hypotheses: (1) in an area of high human density and low persecution, crows should habituate to human beings near their nests and (2) in areas of high persecution, crows should show avoidance behavior to human intruders near their nests.

Exotic Birds: A Growing Problem with No Easy Solution

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The Problem of Avian Extinctions

Studying endangered birds and developing programs to prevent their extinction have become principal endeavors of bird conservationists worldwide. More than perhaps any other group of vertebrate biologists, ornithologists have responded to the contemporary threat of accelerated extinction rates with intensive research and management efforts. This responsiveness may be owing to the fact that many threatened or endangered birds are relatively well known so that their extinctions would represent the loss of organisms whose importance has already been demonstrated in terms of scientific advancement, contributions to ecological systems, commercial and recreational activities, or esthetic considerations. Furthermore, the generally advanced state of our knowledge of birds has facilitated the rapid development of management techniques. Ornithologists are often able to quickly identify the threats to a species and propose a diverse arsenal of proven management approaches that can prevent the species’ extinction. As a result, management of endangered birds has set standards to which conservationists concerned with other taxonomie groups refer.

Bioaccumulation Patterns and Temporal Trends of Mercury Exposure in Wisconsin Common Loons

A long term field study was initiated by the Wisconsin Department of Natural Resources in 1992 to elucidate patterns of common loon (Gavia immer) mercury (Hg) exposure. Analysis of loon blood and feather samples collected from recaptured adult loons in Wisconsin 1992–2000 found evidence of a decline in overall body burdens of mercury in common loons for this region. The interval between sampling individual loons spanned 2–8 years, a sufficient length of time to observe a change in tissue Hg concentrations. Loon chick blood Hg levels declined by 4.9% annually for chicks sampled on 33 lakes during the period 1992–2000. This is the first evidence we are aware of showing a recent regional annual decrease in common loon Hg exposure. Repeated captures of wild loon chicks in Wisconsin shows that blood Hg concentrations can increase during the period of rapid feather growth (weeks 2–5), although the rate of increase is very slow. Mean egg Hg levels ranged from 0.19 to 0.87 µg Hg/g wet weight (ww) in samples collected 1996–2000. Egg Hg concentration was inversely and significantly related to lake pH (p<0.0001; r2=0.55). Adults and chicks were often captured simultaneous during the period 1992–2000. Correlations were highest between sibling blood Hg levels (r=0.88) and chick blood and adult blood (male r=0.61, female r=0.52) Hg levels, likely reflecting the influence of the Hg content of prey from the natal lake on loon blood Hg levels. The relationship between feathers and blood of adults and that of chick blood and adult feathers was weaker.