Carola A. Haas

Effects of seven silvicultural treatments on terrestrial salamanders

We compared the relative abundance of terrestrial salamanders before and after application of seven regeneration treatments in a low-elevation, southern Appalachian hardwood forest in southwest Virginia. Treatments included understory removal, group selection, two shelterwoods, leave-tree, clearcut, and a control. Salamander relative abundance was significantly lower after harvest on the group selection (pa0.005), shelterwoods (pa0.007 and pa0.015), leave-tree (pa0.001), and clearcut treatments (pa0.001). There was no significant difference in relative abundance during the same period on the control (pa0.788) or understory removal (pa0.862) treatments. # 1999 Elsevier Science B.V. All rights reserved.

Conservation of Grassland Birds in North America: Understanding Ecological Processes in Different Regions: "Report of the AOU Committee on Conservation"

—Many species of birds that depend on grassland or savanna habitats have shown substantial overall population declines in North America. To understand the causes of these declines, we examined the habitat requirements of birds in six types of grassland in diff erent regions of the continent. Open habitats were originally maintained by ecological drivers (continual and pervasive ecological processes) such as drought, grazing, and fi re in tallgrass prairie, mixed-grass prairie, shortgrass prairie, desert grassland, and longleaf pine savanna. By contrast, grasslands were created by occasional disturbances (e.g., fi res or beaver [Castor canadensis] activity) in much of northeastern North America. The relative importance of particular drivers or disturbances diff ered among regions. Keystone mammal species—grazers such as prairie-dogs (Cynomys spp.) and bison (Bison bison) in western prairies, and dam-building beavers in eastern deciduous forests—played a crucial, and frequently unappreciated, role in maintaining many grassland systems. Although fi re was important in preventing invasion of woody plants in the tallgrass and moist mixed prairies, grazing played a more important role in maintaining the typical grassland vegetation of shortgrass prairies and desert grasslands. Heavy grazing by prairiedogs or bison created a low “grazing lawn” that is the preferred habitat for many grassland bird species that are restricted to the shortgrass prairie and desert grasslands. Ultimately, many species of grassland birds are vulnerable because people destroyed their breeding, migratory, and wintering habitat, either directly by converting it to farmland and building lots, or indirectly by modifying grazing patt erns, suppressing fi res, or interfering with other ecological processes that originally sustained open grassland. Understanding the ecological processes that originally maintained grassland systems is critically important for eff orts to improve, restore, or create habitat for grassland birds and other grassland organisms. Consequently, preservation of large areas of natural or seminatural grassland, where these processes can be studied and core populations of grassland birds can fl ourish, should be a high priority. However, some grassland birds now primarily depend on artifi cial habitats that are managed to maximize production of livestock, timber, or other products. With a sound understanding of the habitat requirements of grassland birds and the processes that originally shaped their habitats, it should be possible to manage populations sustainably on “working land” such as catt le ranches, farms, and pine plantations. Proper management of private land will be critical for preserving adequate breeding, migratory, and winter habitat for grassland and savanna species. Received 12 December 2006, accepted 24 April 2007. Resumen.—Muchas especies de aves que dependen de habitats de pastizal o savana han mostrado disminuciones signifi cativas en sus poblaciones en Norte America. Para poder entender las causas de estas disminuciones examinamos los requerimientos de habitat de aves 8E-mail: raask@conncoll.edu. Coauthors are listed alphabetically. 9U.S. Department of Interior (retired). ORNITHOLOGICAL MONOGRAPHS NO. 64 2 Bird species that depend on grassland and shrubland have declined in many regions in eastern and central North America during the past century, and open-country species frequently outnumber woodland species on state lists of endangered and threatened species (Askins 1993). Grassland birds, in particular, appear to be in trouble; during the past 25 years they have shown “steeper, more consistent, and more geographically widespread declines than any other behavioral or ecological guild” of North American birds (Knopf 1994:251). An analysis of continent-wide population trends on Breeding Bird Survey (BBS) routes between 1966 and 2002 showed that only 3 of 28 species of grassland specialists increased signifi cantly, whereas 17 species decreased signifi cantly (Sauer et al. 2003). Although some species that showed a continent-wide population decline were increasing in particular regions, many species (including Bobolink [Dolichonyx oryzivorus] and Eastern Meadowlark [Sturnella magna]) declined throughout almost their entire breeding range. Population declines of grassland birds have occurred not only in the northeastern United States (Vickery 1992), where regenerating forest has replaced much of the farmland that dominated the landscape in the 18th and 19th centuries (Norment 2002), but also in the Midwest (Herkert 1995) and the Great Plains (Knopf 1994), the historical centers of abundance and diversity of grassland birds. Population declines have also occurred in grassland birds in South America (Vickery et al. 1999b), Europe (Newton 1998), and other parts of the world (Goriup 1988). Although declines in particular grassland bird populations can be att ributed to a wide variety of factors, such as habitat fragmentation, nest parasitism, pesticides, and invasion by woody vegetation (Peterjohn and Sauer 1999), an overriding cause of regional declines appears to be agricultural intensifi cation. Because most natural grasslands were converted to farmland or are used as ranchland, grassland birds now largely depend on habitats that are managed for agricultural production. Although farmland and pasture may provide good breeding or wintering habitat for some grassland bird species (e.g., Wunder and Knopf 2003), their suitability oft en declines as agriculture becomes more effi cient. Agricultural intensifi cation involves a shift toward monocultures that support fewer natural species (Matson et en seis regiones del continente. Habitats abiertos originalmente se mantenían por conductores ecológicos (procesos ecológicos continuos y perdurables), como sequía, pastoreo, y/o fuego como en praderas de pastizal alto, mediano, y corto, pastizal desértico y sabana de pino de hoja larga. En contraste, los pastizales se crearon por disturbios ocasionales (fuego o actividad de castores) en el noreste de Norte America. Especies claves de mamíferos (como perrito de las praderas y bisonte en las praderas del oeste y castores en bosque deciduos del este) jugaron un papel crucial, y frecuentemente no apreciado, manteniendo sistemas de pastizales. Mientras el fuego fue importante en prevenir la invasión de especies leñosas en praderas de pastizal alto y mediano, el pastoreo jugo un papel mas importante en mantener la vegetación típica de pastizales cortos y desérticos. Alta presión de pastoreo por perrito de las praderas y bisontes crearon una capa de “césped pastoreado” que es el habitat preferido por algunas especies de aves de pastizal que están restringidas a las Grandes Planicies y pastizales desérticos. Muchas especies de aves de pastizal estan vulnerables porque la actividad humana ha destruido sus habitats de anidacion, migración e invernacion directamente mediante la conversión a áreas de cultivo o construcción, o indirectamente mediante la modifi cación de patrones de pastoreo, supresión de fuego, o interfi riendo con otros procesos ecológicos que originalmente mantenían el pastizal abierto. El entendimiento de los procesos ecológicos que mantenían el sistema de pastizal es sumamente importante para esfuerzos de mejoramiento, restauración, o creación de habitats para aves de pastizal y otros organismos. Consecuentemente, de alta prioridad debería de ser la preservación de grandes áreas de pastizal natural o seminatural donde estos procesos se podrían estudiar. Sin embargo, muchas especies de pastizal ahora dependen principalmente de habitats artifi ciales manejados para maximizar la producción de ganado, madera, u otros productos. Con un claro entendimiento de los requerimientos de habitat de aves de pastizal y los procesos que originalmente moldearon sus habitats seria posible mantener sus poblaciones en terrenos manejados como ranchos ganaderos, granjas, y plantaciones de pino. El manejo apropiado de tierras privadas será critico para la preservación adecuada de areas de habitat de anidacion, migración e invernacion para aves de pastizal y savana. CONSERVATION OF GRASSLAND BIRDS 3 al. 1997), and the channeling of more primary production toward food or fi ber. In a broad sense, intensifi cation would include conversion of rangeland to cropland, and the shift to the use of exotic grasses and forbs in pastures and hay meadows. A suite of factors associated with agricultural intensifi cation tend to degrade grassland bird habitat: these include increased use of pesticides, removal of natural fi eld edges, spring plowing, land drainage, replacement of mixed farms with farms dominated by one crop, harvesting or mowing earlier in the season when birds are still nesting, and higher stocking rates for livestock (Newton 1998). Murphy (2003) showed that population changes in grassland birds in eastern and central North America between 1980 and 1998 were highly correlated with changes in agricultural land use in their breeding areas. The most important factor was loss of rangeland, which was associated with negative population trends for 12 species of grassland birds. Rangeland is used for livestock production, but it generally is not managed as intensively as cropland or pasture and it is dominated by native species of plants, providing habitat for a diverse group of grassland birds (Peterjohn 2003). In the Midwest, population declines in several species of grassland birds are highly correlated with declines in the combined area of pasture and hay meadow (Herkert et al. 1996). Our goal is to provide recommendations for halting and reversing the decline in grassland birds. In some cases, this may be accomplished by restoring natural grasslands, but in other cases it is more realistic to try to promote farming and ranching methods that make the land both economically productive and biologically diverse. In either case, it is impo

Energetics of surface‐active terrestrial salamanders in experimentally harvested forest

ABSTRACT Environmental temperatures affect nearly all aspects of ectotherm physiology, including terrestrial salamanders. Therefore, habitat disturbances that alter temperature regimes may interact with physiological processes to affect energy budgets of salamanders or constrain surface activity and possibly lead to changes in population-level parameters. We hypothesized that warmer surface temperatures following harvesting of canopy trees could cause surface-active salamanders to expend more energy for metabolism, potentially leaving a smaller proportion of the energy budget available for reproduction or storage. From 2006 to 2008, we quantified temperature regimes of salamander refugia in a field experiment replicated at 4 sites that included plots subjected to a timber harvest and plots not manipulated during this time period. At each site, we quantified temperature regimes in regenerating forest stands which, approximately 10 years earlier, experienced a range of harvest intensity from shelterwood to silvicultural clearcut. Further, we compared energetic parameters including 1) calories required to maintain homeostasis across an active season, 2) abundance of available potential energy (i.e., invertebrate prey), and 3) a measure of growth and storage (i.e., body condition index) among silvicultural treatments for surface-active salamanders. For surface-active eastern red-backed salamanders (Plethodon cinereus), mean calories required for maintenance were approximately 33% greater in recently harvested forest compared to unharvested controls, but body condition was inconsistent among treatments, and invertebrate abundances were similar among treatments but differed by study site. In contrast, we did not detect a treatment effect in any energetic metric 8–14 growing seasons after harvesting. Given that surface-active salamanders in recently harvested forest may be forced to restrain behaviors associated with foraging and mating or trade-off growth or reproduction for increased basic maintenance costs, energetics may be an important but overlooked short-term contributor to observed changes in abundances, reproductive demography, or surface activities after timber harvesting. Managing for both the rapid recovery of understory vegetation and retention of large stumps and logs may help mitigate warming of microclimate for salamanders and should be considered further.

Home Range and Habitat Selection of Bog Turtles in Southwestern Virginia

Bog turtle (Clemmys muhlenbergii). populations are believed to be declining, in part, because of habitat loss. However, a detailed understanding of the specific habitat requirements for bog turtles is lacking. We used radiotelemetry on adult bog turtles to examine home range size (M: n = 13; F: n = 12) and habitat selection (M: n = 12; F: n = 17) at 3 sites in southwestern Virginia from May 1995 to December 1996. Home range size did not differ between males and females, as calculated via minimum convex polygon (MCP) analysis (P = 0.785) or cluster analysis (P = 0.722) during the 20-month study period. Habitat selection also did not differ by sex (P = 0.441). Mean 95% home range area pooled across sexes was 0.52 ha via MCP analysis and 0.15 ha via cluster analysis. We located bog turtles in areas closer to patches of shallow water, in deeper mud (21 cm) and water (9 cm), and in taller (55 cm), denser vegetation than expected if selection was random. Bog turtles selected wet meadow, smooth alder (Alnus serrulata) edge, and bulrush (Scirpus spp.) vegetation types more than expected randomly, and avoided dry meadow vegetation and streams. This species selects multiple microhabitats within wetlands and is restricted to small home ranges. Future bog turtle habitat conservation in southwestern Virginia should identify occupied wetlands containing the habitat components we describe, quantify management practices aimed at slowing succession and habitat loss, and reduce threats that may affect wetland hydrology.

Movements and Activity of Bog Turtles (Clemmys muhlenbergii) in Southwestern Virginia

We radio-tracked 35 adult bog turtles (Clemmys muhlenbergii) at four study sites in south- western Virginia (May 1995 to December 1996) to assess the scale and frequency of movement within and between wetlands and to identify the potential for population isolation. Net movements between subse- quent locations recorded during 1995 (N = 18) and 1996 (N = 27) averaged 17 m and 18 m for females and 16 m and 23 m for males, respectively, and did not differ with respect to sex for either year. Net distances underestimated true bog turtle activity (measured by threadspooling) by a factor of 6.5. The length of time between net distance measurements (1-9 d) did not influence the resulting distance measured, suggesting that relatively short time intervals may not need to be considered when calculating activity estimates. Sev- enty-five percent of all net movements were 100 m. Large-scale movements between wetlands were observed infrequently. Information regarding distance, timing, and proximate cues for movement is essential to further understanding of the behavior and ecology of turtles. Dispersal, al- though poorly studied, has profound implications for social behavior, genetic structure, and persistence of populations. If successful dispersal is limited to infrequent, large-scale movements, future wetland loss may serve to isolate some populations of bog turtles. Further study of the importance long-distance movements play in maintaining populations is needed to aid future conservation strategies in southwestern Virginia.

Brood parasitism by brown-headed cowbirds on brown thrashers : Frequency and rates of rejection

Rates of brood parasitism by Brown-headed Cowbirds Molothrus ater on nests of Brown Thrashers Toxostoma rufum in south-central North Dakota ranged from 3% to 18% from 1984-1986. The average observed rate of parasitism, 12%, was higher than typically reported for Brown Thrashers. We conducted an experiment to determine if these high observed rates of parasitism were a result of unusually high rates of parasitism by cowbirds or unusually low rates of rejection by thrashers. Brown Thrashers removed 58% of experimentally-placed cowbird eggs. This rate of rejection is significantly lower than that previously reported for Brown Thrashers and for other rejector species. We conclude that thrashers in this area are parasitized at a high rate, but that low rates of rejection are at least partially responsible for the high observed rate of parasitism. These results suggest that the classification of Brown Thrashers as a rejector species should be reevaluated and that further study of geographic variation in cowbird host behavior and the role of learning in egg recognition is warranted.

Factors Related to Occupancy of Breeding Wetlands by Flatwoods Salamander Larvae

The flatwoods salamander (Ambystoma cingulatum) was listed as federally threatened in 1999. Alteration of habitat was considered the main threat to the species, especially the loss of habitat for larval flatwoods salamanders that develop in isolated, seasonally flooded wetlands. Our objectives were to evaluate a suite of within-pool factors (i.e., vegetation structure, water level, and an index to presence of fish) that could influence occupancy of breeding wetlands by larval flatwoods salamanders on Eglin Air Force Base in Florida, USA. We dip-netted for larval salamanders from January through March 2003–2006 and we measured a suite of vegetation characteristics in 2006–2007. Further, in 2006 we measured the level of water and relative presence of fish over the salamander breeding season. Site occupancy over the four year period was best described by a model that incorporated high herbaceous vegetation cover and open canopy cover. Detection probability was assessed, but it varied among years and was not included in the model. Our study suggests that managing the breeding habitat of flatwoods salamander for open canopies and dense herbaceous vegetation may contribute to this species’ recovery.

Spatial Interactions between Two Species of Frogs: Rana okaloosae and R. clamitans clamitans

Abstract Rana okaloosae is endemic to northwestern Florida and is sympatric with R. clamitans clamitans, its closest relative and possibly its main interspecific competitor. We evaluated the movements, dynamic interactions, and nearest neighbor distances of male R. okaloosae and R. c. clamitans in Okaloosa County, Florida. Mean minimum daily distances moved and maximum daily distances moved were greater for R. c. clamitans than R. okaloosae. Dynamic interactions tended to be positive and suggested that there were positive associations between individuals of the two species. Further, nearest neighbor analyses suggested that calling males of both species were positioned in a clumped distribution on any single night. The intraspecific and interspecific interactions of these species were complex and suggested that these species may have selected similar calling locations and appeared not to exclude either conspecifics or heterospecifics.

Effects of Repeated-Stand Entries on Terrestrial Salamanders and their Habitat

Abstract In recent years, silivicultural methods have shifted away from clearcut harvesting towards greater retention of overstory trees through part or all of a rotation. However, little is known about the effects of partial harvesting on wildlife populations. Thus, we examined effects of high-leave shelterwood management on terrestrial salamanders prior to and after an initial harvest and a subsequent overstory removal harvest (ORH) 13 years later. On an experimental research site in southwestern Virginia, we compared changes in salamander captures in this plot to a clearcut and control plot 1994–1996 and 2007–2009. Compared to contemporaneous estimates from an unharvested control, salamander captures were lower on shelterwood and clearcut plots 2-years after the initial harvest (1996) and lower on the shelterwood plot 1- and 2-years after the ORH (2008, 2009). Captures of the most common species, Plethodon cinereus (Eastern Red-backed Salamanders), followed similar trends with fewer captures in both harvested plots 2-years after the initial harvest (1996), but only the ORH differed from the control 2-years after the second partial harvest (2009). Abundance of woody debris was greater in the shelterwood following the ORH but was more decayed in the control plot. The regenerating clearcut (14 years post-harvest) had deeper leaf litter and denser understory vegetation than the ORH. These data are some of the first available describing effects of multiple harvest entries on terrestrial salamanders and suggest cumulative negative impacts on salamanders may occur from partial harvesting systems. More long-term monitoring of salamander populations is justified in silvicultural systems with multiple entries within a rotation.

Hindcasting Historical Breeding Conditions for an Endangered Salamander in Ephemeral Wetlands of the Southeastern USA: Implications of Climate Change

The hydroperiod of ephemeral wetlands is often the most important characteristic determining amphibian breeding success, especially for species with long development times. In mesic and wet pine flatwoods of the southeastern United States, ephemeral wetlands were a common landscape feature. Reticulated flatwoods salamanders (Ambystoma bishopi), a federally endangered species, depend exclusively on ephemeral wetlands and require at least 11 weeks to successfully metamorphose into terrestrial adults. We empirically modeled hydroperiod of 17 A. bishopi breeding wetlands by combining downscaled historical climate-model data with a recent 9-year record (2006–2014) of observed water levels. Empirical models were subsequently used to reconstruct wetland hydrologic conditions from 1896–2014 using the downscaled historical climate datasets. Reconstructed hydroperiods for the 17 wetlands were highly variable through time but were frequently unfavorable for A. bishopi reproduction (e.g., only 61% of years, using a conservative estimate of development time [12 weeks], were conducive to larval development and metamorphosis). Using change-point analysis, we identified significant shifts in average hydroperiod over the last century in all 17 wetlands. Mean hydroperiods were shorter in recent years than at any other point since 1896, and thus less suitable for A. bishopi reproduction. We suggest that climate change will continue to impact the reproductive success of flatwoods salamanders and other ephemeral wetland breeders by reducing the number of years these wetlands have suitable hydroperiods. Consequently, we emphasize the importance of conservation and management for mitigating other forms of habitat degradation, especially maintenance of high quality breeding sites where reproduction can occur during appropriate environmental conditions.