Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact helpdesk@bioone.org with any questions.
Small mammals are ubiquitous members of vertebrate communities that are sensitive to habitat change. In the Great Lakes region of North America, small mammal communities have changed rapidly, but experimental tests of potential mechanisms are lacking. Using a before-after, control-treatment design, we quantified the response of small mammals to single-tree selection harvest in Laurentian hardwood forests of Wisconsin, United States. We documented changes in forest structure and small mammal abundance, species diversity, and community similarity from silvicultural treatment. Treatment reduced tree density and canopy cover and increased mean tree diameter, woody stem density, variation in woody stem density, and volume of coarse woody debris. Peromyscus and northern short-tailed shrews (Blarina brevicauda) were dominant community members across treatments and years. White-footed mice (P. leucopus) outnumbered woodland deer mice (P. maniculatus gracilis) before treatment, but declined by almost fifty percent after treatment; deer mice and total rodent (i.e., Rodentia) abundances were unchanged. Small mammal species diversity increased twofold following treatment. Our experiment identified species-specific responses within Peromyscus to timber harvest: white-footed mice, the numerically dominant and generalist species, were most sensitive to habitat change, and their response produced cascading effects to small mammal community structure. Future experiments should assess these small mammal responses in a multi-year framework and quantify their effects on the broader vertebrate community.
Although it is known that southern flying squirrels (Glaucomys volans) nest in larger groups to offset the energetic costs of low temperatures, the influence of other variables on aggregation size remains relatively unknown. Therefore, the influence of environmental variables and individual characteristics of G. volans on nest box aggregation size was studied from 1992–1998 at the Savannah River Site in South Carolina. Over the study period, 5859 occupied boxes were observed, representing 11,238 captures and 2671 unique individuals. The majority of occupied boxes (60.3%) contained solitary individuals, while 26.1% contained aggregations (≥2 individuals) of adult and/or subadult individuals and 13.6% contained litters. Although ambient temperature is widely believed to be the most important variable influencing aggregation size of G. volans, the final model explaining nest aggregation size for G. volans included not only minimum daily ambient temperature, but also Julian date and individual G. volans characteristics of sex, age, and reproductive status. Minimum ambient temperature was inversely related to aggregation size, with larger aggregation sizes associated with winter months, although aggregation size sharply increased between the months of Aug.–Sept. The retention of Julian date in the final model, in addition to minimum ambient temperature, indicates that behavioral shifts due to seasonal changes, independent of temperature, should be considered. Nestlings were associated with larger aggregation sizes, as were inactive and lactating females and inactive males. However, sex alone did not significantly contribute to the final model. This study demonstrates that in addition to temperature, there are a suite of predictors of nest aggregation size for G. volans that should be considered when evaluating nest box occupancy for this species.
Daily and seasonal fluctuations in environmental conditions can significantly impact the survivorship and reproductive success of animals by altering energetic costs and predation risks. Behaviorally, animals often respond to changes in their environment through regulation of activity and associated movement patterns. We used accelerometer-informed GPS telemetry to assess nightly activity and movement patterns in response to environmental conditions in a small endotherm, the eastern spotted skunk (Spilogale putorius). Nightly movements and activity of skunks were monitored in association with ambient temperature, precipitation, and moon illumination during late winter through summer in Alabama. Eastern spotted skunks were strictly nocturnal, exhibiting almost no daytime activity. Total time active and total distance moved each night increased with ambient temperature and rainfall. Variation in moon illumination, which may affect predation risk, did not impact skunk nightly activity or movement. Eastern spotted skunks likely reduce predation risk by being active between sunset and sunrise when they are less visible to predators. Lower activity and movement at cooler temperatures significantly reduces thermoregulatory costs for small endotherms. Increased activity of skunks during or shortly after precipitation may be driven by increased prey availability. Our findings indicate that small endotherms, like the eastern spotted skunk, rely extensively on behavioral thermoregulation, instead of physiological adaptation, to buffer themselves against changing environmental conditions. Behavioral flexibility may promote species persistence as climate changes, and should be considered in conservation strategies of vulnerable species, such as eastern spotted skunks.
Within the Great Plains region of North America, oxbow wetlands were lost as streams were channelized and straightened to allow for agricultural use of the landscape. Topeka Shiner, which rely on these oxbow wetlands, have declined in abundance, currently occupy 20% of their historical geographic range, and are now an endangered species. A large emphasis has been placed on restoring oxbow wetlands to recover Topeka Shiner populations. As the number of oxbow restorations has increased, so has the number of monitoring projects focused on these habitats. Currently, conservation practitioners rely on the presence of Topeka Shiner to determine the success of an oxbow restoration. Given the rarity of the species, this method is likely ineffective. Within this study we attempt to create a model that can be used to determine the success of an oxbow restoration that will benefit the Topeka Shiner without relying on the presence of the species in the wetland. We used multiple fish community metrics and modelling strategies to determine the best model for predicting Topeka Shiner CPUE and presence/absence within oxbows. We determined that the top models were ineffective at predicting Topeka Shiner CPUE and presence/absence. Our findings illustrate the random nature by which fish communities become established within oxbows, and the island-like nature of oxbows in terms of how fish communities may become established and change over time. These findings indicate that the success of oxbow restoration for Topeka Shiner needs to be defined at a larger scale than for individual oxbows. Furthermore, our findings corroborate the inability of previous studies to determine reproducible associations of Topeka Shiner with various fish community metrics.
The Poweshiek skipperling (Oarisma poweshiek) was once a common prairie butterfly in central North America, but is now critically endangered in Canada and the United States. The Poweshiek skipperling is confined to the largest remaining tall grass prairie in Canada, which is currently managed using grazing and fire to maintain prairie habitat and prevent forest and shrub encroachment. To support re-introduction, restocking, and recovery of this critically endangered species, it is necessary to understand the habitat conditions preferred by skipperlings. By surveying prairie sites with Poweshiek skipperling across age and treatment categories (1–2 y since burn, 4–6 y since burn, >15 y since burn, and grazing), we identified commonly-used nectar plants and recorded physical variables known to influence plant diversity. We measured soil variables, including macronutrients, compaction, pH, texture, and moisture content, and used multivariate statistics to test for significant differences in site characteristics and plant community across treatments. For each site, we captured plant diversity, abundance, and cover, as well as total plant biomass. We found the oldest burn sites had the fewest skipperlings. Intermediate burn sites and lightly grazed sites contained the most skipperlings. In 95% of nectaring observations, adult skipperlings were feeding on Black-eyed Susan (Rudbeckia hirta), upland white aster (Solidago ptarmicoides), and Self-heal (Prunella vulgaris). Characteristics in the physical components of sites and plant communities did not significantly differ across treatment types for most variables with the exception of the oldest burns, which showed significantly higher levels of soil compaction, live biomass, bare ground, less flowering species during the flight period, less flowering stems, and increased presence of nonnative and invasive species. Poweshiek skipperling is at high risk of imminent extirpation, and we recommend that the management regimes be adjusted to plan for a consistent supply of habitat conditions and plant species composition exemplified by our intermediate burn sites. We suggest fire return intervals of 4–6 y using patch burns in combination with grazing, permitted at times that minimize the impact on immature stages of Poweshiek skipperling. This management is needed to provide suitable habitat conditions to maintain the current population and allow for successful restocking and recovery.
Urban prairie “gardens/plots” are gaining popularity for providing similar ecological services as remnant and restored prairies, which are predominantly found in rural areas. However, it is not known to what extent small urban prairies can sustain the plant-pollinator interactions that are vital to both the insects and the plants. The goal of our research was to examine plant/pollinator interactions in three urban prairies in southwest Missouri and compare them to rural managed/restored prairies using a visit-based approach. Urban prairies were all in Springfield, Mo. and shared similar habitat matrices (within an area of 8 km2); rural prairies were located within 68 km of urban prairies, shared similar habitat matrices to each other, and shared soil edaphic characteristics with an urban prairie. From May through August 2018 in all six prairies, we observed the five most abundant forbs in bloom, the number of pollinator visits by bees, butterflies/moths, wasps, beetles, and flies; and, pollinator fidelity from dawn to dusk. The areas observed within a prairie, hereafter “plot(s)”, were determined randomly by where at least two plants of the same species, out of the five most abundant forbs, were located. Using these criteria of observations on the five most abundant species across six prairies and four months, a total of 66 forb species were identified, with 58 of the species native to tallgrass prairies. However, only eight of the 58 native forb species were shared across urban and rural prairies. Jaccard similarity indices indicate lower similarity of the five abundant forbs within urban plots (9%) when compared to rural plots (24%), and low similarity between urban and rural plots (9%). Insect visitation varied by prairie type (rural/urban), month, and insect group; however, urban plots received 61% of the total visits compared to 39% in rural plots. Bees accounted for 5913 visits out of 10,113 visits recorded; high bee visits were similar in urban and rural plots. Insect fidelity was over 97% and did not significantly differ between rural and urban prairies. Therefore, the lack of similarity among and across urban and rural prairies in dominant species did not affect insect visitation rates or fidelity in our study. Our results suggest that establishment and management of urban prairie gardens and plots of various size may sustain the same or greater levels of pollinator services as rural prairies.
Black fly larval collection sites at three rivers in central Washington state all possess taxa of the Simulium arcticum Malloch complex with the autosomal inversion, IS-1, in high enough frequency to test for Hardy-Weinberg equilibrium independently at each site. Such tests determine reproductive status of the taxa present. These situations in which the IS-1 autosomal inversion is in relative high frequency are rare. Moreover, earlier molecular comparisons suggest a single taxon for the S. arcticum complex and cytogenetic studies at the local level may or may not support earlier molecular work. Such knowledge could further our understanding of the proper taxonomy of these taxa, that is, whether they are good biological species or not. I scored the three genotypes of the IS-1 inversion in 247 larvae to test the reproductive status of populations of three members of the Simulium arcticum complex (Simulium brevicercum, S. saxosum, and the newly discovered cytotype (S. arcticum IIL- 81) at the Methow, Entiat and Wenatchee rivers of Washington state. In all three cases, larvae conformed to Hardy-Weinberg equilibrium, suggesting these populations were panmictic when the collections were made. Thus, these results support earlier molecular work and indicate that the three taxa at these sites can freely interbreed.
Recolonization by native species following removal of invasive plant species can often be uneven and lead to the rapid increase of one or a few native plant species. This can result in the formation of a significant resource pulse that may consequently affect populations of herbivorous species and their natural enemies. Here we present results from observations of parasitism rates during a localized outbreak of the Asimina webworm moth, Omphalocera munroei, a locally monophagous herbivore of the common paw-paw. Asimina triloba. This outbreak initiated from locations of increased understory growth of A. triloba, following the removal of Amur Honeysuckle (Lonicera maackii). Parasitism rates during the outbreak reached 50%, with higher parasitism rates observed in larvae collected at the end of the local outbreak relative to those the year following the peak of the outbreak. Parasitism rates remained high 3 y after the end of the local O. munroei outbreak, indicating >7 y of high parasitoid densities. O. munroei emerges late in the growing season, making it fairly inaccessible as a host or prey to many generalist predators/parasitoids, which emerge earlier the following year. This suggests the O. munroei outbreak potentially contributed to an increase in natural enemy pressure of other native species in the community.
This article is only available to subscribers. It is not available for individual sale.
Access to the requested content is limited to institutions that have
purchased or subscribe to this BioOne eBook Collection. You are receiving
this notice because your organization may not have this eBook access.*
*Shibboleth/Open Athens users-please
sign in
to access your institution's subscriptions.
Additional information about institution subscriptions can be foundhere