We used North American Breeding Bird Survey data (1966-91) to estimate distribution, relative abundance, and population trends of quails. Population trends in grassland/shrub birds sympatric with northern bobwhite (Colinus virginianus) were also examined. Northern bobwhite and scaled quail (Callipepl,a squamata) populations have declined since 1966. Rates of decline for these quails have increased during the past decade. California quail (C. califomica), Gambel's quail (C. gambelii), and mountain quail (Oreortyx pictus) populations have been stable over the long-term (1966-91). However, the short-term (1982-91) trend for California quail is positive, whereas Gambel's quail appear to be declining. Patterns in trends indicate similar factors may be negatively affecting breeding populations of grassland/shrub birds throughout the bobwhite's range. We discuss plausible hypotheses to explain population trends and recommend future action.
The majority of pollinating insects are generalists whose lifetimes overlap flowering periods of many potentially suitable plant species. Such generality is instrumental in allowing exotic plant species to invade pollination networks. The particulars of how existing networks change in response to an invasive plant over the course of its phenology are not well characterized, but may shed light on the probability of long-term effects on plant-pollinator interactions and the stability of network structure. Here we describe changes in network topology and modular structure of infested and non-infested networks during the flowering season of the generalist non-native flowering plant, Cirsium arvense in mixed-grass prairie at Badlands National Park, South Dakota, USA. Objectives were to compare network-level effects of infestation as they propagate over the season in infested and non-infested (with respect to C. arvense) networks. We characterized plant-pollinator networks on 5 non-infested and 7 infested 1-ha plots during 4 sample periods that collectively covered the length of C. arvense flowering period. Two other abundantly-flowering invasive plants were present during this time: Melilotus officinalis had highly variable floral abundance in both C. arvense-infested and non-infested plots and Convolvulus arvensis, which occurred almost exclusively in infested plots and peaked early in the season. Modularity, including roles of individual species, and network topology were assessed for each sample period as well as in pooled infested and non-infested networks. Differences in modularity and network metrics between infested and non-infested networks were limited to the third and fourth sample periods, during flower senescence of C. arvense and the other invasive species; generality of pollinators rose concurrently, suggesting rewiring of the network and a lag effect of earlier floral abundance. Modularity was lower and number of connectors higher in infested networks, whether they were assessed in individual sample periods or pooled into infested and non-infested networks over the entire blooming period of C. arvense. Connectors typically did not reside within the same modules as C. arvense, suggesting that effects of the other invasive plants may also influence the modularity results, and that effects of infestation extend to co-flowering native plants. We conclude that the presence of abundantly flowering invasive species is associated with greater network stability due to decreased modularity, but whether this is advantageous for the associated native plant-pollinator communities depends on the nature of perturbations they experience.
Gretchen Lebuhn,∗ ¶ Sam Droege,† Edward F. Connor,∗ Barbara Gemmill-Herren,‡ Simon G. Potts,§ Robert L. Minckley,∗∗ Robert P. Jean,†† Emanuel Kula,‡‡ David W. Roubik,§§ Karen W. Wright,∗∗∗ Gordon Frankie,††† and Frank Parker‡‡‡ ∗Department of Biology, San Francisco State University, San Francisco, CA 94132, U.S.A. †USGS Patuxent Wildlife Research Center, 12100 Beech Forest Road, Laurel, MD 20708-4039, U.S.A. ‡Food and Agriculture Organization of the United Nations, viale delle Terme di Caracalla, Rome 00100, Italy §Centre for Agri-Environmental Research (CAER), School of Agriculture, Policy and Development, University of Reading, RG6 6AR, United Kingdom ∗∗Department of Biology, University of Rochester, Rochester, NY 14627, U.S.A. ††Department of Sciences and Mathematics, Saint Mary-of-the-Woods College, St. Mary of the Woods, IN 47876, U.S.A. ‡‡Faculty of Forestry and Wood Technology, Mendel University of Agriculture and Forestry, Zemědělska 3 CZ-61300 Brno 420 545 134 127, Czech Republic §§Smithsonian Tropical Research Institute, Box 0843–03092 Balboa Ancon, Republic of Panama ∗∗∗Sevilleta LTER, Department of Biology 167 Castetter Hall, MSC03 20201, University of New Mexico, Albuquerque, NM 87131-0001, U.S.A. †††Dept of Environmental Science, Policy, & Management, University of California, Berkeley, CA 94720, U.S.A. ‡‡‡USDA-ARS Bee Biology and Systematics Lab, Utah State University, Logan, UT 84322, U.S.A.
Summary Analyses of flower‐visitor interaction networks allow application of community‐level information to conservation problems, but management recommendations that ensue from such analyses are not well characterized. Results of modularity analyses, which detect groups of species (modules) that interact more with each other than with species outside their module, may be particularly applicable to management concerns. We conducted modularity analyses of networks surrounding a rare endemic annual plant, Eriogonum visheri, at Badlands National Park, USA, in 2010 and 2011. Plant species visited were determined by pollen on insect bodies and by flower species upon which insects were captured. Roles within modules (network hub, module hub, connector and peripheral, in decreasing order of network structural importance) were determined for each species. Relationships demonstrated by the modularity analysis, in concert with knowledge of pollen species carried by insects, allowed us to infer effects of two invasive species on E. visheri. Sharing a module increased risk of interspecific pollen transfer to E. visheri. Control of invasive Salsola tragus, which shared a module with E. visheri, is therefore a prudent management objective, but lack of control of invasive Melilotus officinalis, which occupied a different module, is unlikely to negatively affect pollination of E. visheri. Eriogonum pauciflorum may occupy a key position in this network, supporting insects from the E. visheri module when E. visheri is less abundant. Year‐to‐year variation in species' roles suggests management decisions must be based on observations over several years. Information on pollen deposition on stigmas would greatly strengthen inferences made from the modularity analysis. Synthesis and applications: Assessing the consequences of pollination, whether at the community or individual level, is inherently time‐consuming. A trade‐off exists: rather than an estimate of fitness effects, the network approach provides a broad understanding of the relationships among insect visitors and other plant species that may affect the focal rare plant. Knowledge of such relationships allows managers to detect, target and prioritize control of only the important subset of invasive species present and identify other species that may augment a rare species' population stability, such as E. pauciflorum in our study.
Recently there has been considerable concern about declines in bee communities in agricultural and natural habitats. The value of pollination to agriculture, provided primarily by bees, is >$200 billion/year worldwide, and in natural ecosystems it is thought to be even greater. However, no monitoring program exists to accurately detect declines in abundance of insect pollinators; thus, it is difficult to quantify the status of bee communities or estimate the extent of declines. We used data from 11 multiyear studies of bee communities to devise a program to monitor pollinators at regional, national, or international scales. In these studies, 7 different methods for sampling bees were used and bees were sampled on 3 different continents. We estimated that a monitoring program with 200-250 sampling locations each sampled twice over 5 years would provide sufficient power to detect small (2-5%) annual declines in the number of species and in total abundance and would cost U.S.$2,000,000. To detect declines as small as 1% annually over the same period would require >300 sampling locations. Given the role of pollinators in food security and ecosystem function, we recommend establishment of integrated regional and international monitoring programs to detect changes in pollinator communities.
The status of wild bees, the major group of pollinators in most biomes, has gained recognition as an important ecological and economic issue. Insufficient baseline data and taxonomic expertise for this understudied group has hindered efforts to assess the conservation status of the majority of wild bee species. To more objectively address their current conservation status, we drew upon museum collections and the expertise of melittologists (biologists studying non-Apis bees) to compile a complete list of bee species for eastern North America, discriminating those which have and have not been detected during the past 20 years. The vast majority (95% of about 770 eastern North American bee species) have been found again, at least once since 1990. The remaining 37 species were rarely collected before 1990 as well. Some may truly be at risk (or lost). Others are undoubtedly data deficient due to inadequate knowledge of their biology or hosts, or the geographic regions and local habitats where they occur. Distributional and ecological patterns among these missing species are discussed. Most were recorded in the region only from peripheral areas or areas known to be undersampled by recent collectors, such as the southeastern United States. Others are characterized by specialized life histories or they cannot be identified routinely in the absence of taxonomic revisions. Clearly, most eastern North American bee species have persisted until recent times, with no evidence of widespread recent extinctions. An absence of well-documented global extinctions of bee species does not warrant complacency regarding pollinator conservation, as our qualitative method does not lend itself to documenting range contractions, range fragmentation, or declines in abundance and species richness in local bee communities.
Climate change has been of high interest to both the scientific community and the public at large since the phenomenon was first suggested. Subsequently, and with growing evidence of its impending ramifications, numerous studies have attempted to illuminate climate change impacts on bird migration. Migration is a key event in the annual cycle in the reproductive success of birds, and changes in migration in response to climate may indicate that species populations are at risk. Previous studies report earlier arrival dates in response to climate change in many bird species, although specific mechanisms are often difficult to explain at broad spatial and temporal scales. Using a newly revived dataset of historical migration cards for over 870 species and spanning 90 years throughout North America, we are developing an historical baseline of bird arrival dates to compare with contemporary records. Here we chronicle the history and reemergence of the North American Bird Phenology Program. We present two case studies illustrating how data from this program has been used to model historical arrival dates of Ruby-Throated Hummingbird (Archilochus colubris) and Purple Martin (Progne subis) throughout eastern North America. Our results show the importance of considering spatial and temporal variability in understanding patterns of bird spring arrivals.
Abstract The status of wild bees, the major group of pollinators in most biomes, has gained recognition as an important ecological and economic issue. Insufficient baseline data and taxonomic expertise for this understudied group has hindered efforts to assess the conservation status of the majority of wild bee species. To more objectively address their current conservation status, we drew upon museum collections and the expertise of melittologists (biologists studying non-Apis bees) to compile a complete list of bee species for eastern North America, discriminating those which have and have not been detected during the past 20 years. The vast majority (95% of about 770 eastern North American bee species) have been found again, at least once since 1990. The remaining 37 species were rarely collected before 1990 as well. Some may truly be at risk (or lost). Others are undoubtedly data deficient due to inadequate knowledge of their biology or hosts, or the geographic regions and local habitats where they occur. Distributional and ecological patterns among these missing species are discussed. Most were recorded in the region only from peripheral areas or areas known to be undersampled by recent collectors, such as the southeastern United States. Others are characterized by specialized life histories or they cannot be identified routinely in the absence of taxonomic revisions. Clearly, most eastern North American bee species have persisted until recent times, with no evidence of widespread recent extinctions. An absence of well-documented global extinctions of bee species does not warrant complacency regarding pollinator conservation, as our qualitative method does not lend itself to documenting range contractions, range fragmentation, or declines in abundance and species richness in local bee communities.
We provide diagnostic morphological characters to help distinguish males and females of the following species of Nomada: N. augustiana Mitchell, N. bethunei Cockerell, N. fervida Smith, N. fragariae Mitchell, N. lehighensis Cockerell, N. texana Cresson, and N. tiftonensis Cockerell. Based on morphological and DNA barcoding evidence we newly synonymize the following species: N. heligbrodtii Cresson (under N. texana), N. indusata Mitchell (under N. augustiana), N. kingstonensis Mitchell (under N. lehighensis), N. pseudops Cockerell (under N. bethunei), and N. wisconsinensis Graenicher (under N. fervida). We provide full descriptions of the female of N. fragariae and the male of N. lehighensis, both of which were not previously known, and newly designate the lectotype of N. wisconsinensis. We additionally provide comments on the distribution, flight times, and host associations for the treated species.
Bowl and pan traps are now commonly used to capture bees (Hymenoptera: Apiformes) for research and surveys.Studies of how arrangement and spacing of bowl traps affect captures of bees are needed to increase the efficiency of this capture technique.We present results from seven studies of bowl traps placed in trapping webs, grids, and transects in four North American ecoregions (Mid-Atlantic, Coastal California, Chihuahuan Desert, and Columbia Plateau).Over 6000 specimens from 31 bee genera were captured and analysed across the studies.Based on the results from trapping webs and distance tests, the per bowl capture rate of bees does not plateau until bowls are spaced 3-5 m apart.Minor clumping of bee captures within transects was detected, with 26 of 56 transects having index of dispersion values that conform to a clumped distribution and 39 transects having positive Green's index values, 13 with zero, and only four negative. However, degree of clumping was slight with an average value of only 0.06 (the index ranges from -1 to 1) with only five values > 0.15. Similarly, runs tests were significant for only 5.9% of the transects.Results indicate that (i) capture rates are unaffected by short distances between bowls within transects and (ii) that bowls and transects should be dispersed throughout a study site.
We studied the calling patterns of common true katydids (Pterophylla camellifolia) from sound recordings made during August through October 2007 in an oak-hickory forest in western Maryland. Nightly patterns of calling frequency were determined using 1-s samples spaced five min apart. The relationship between calling frequency (i.e., the number of twelve 1-second samples per hour in which singing occurred) and time of night, date, and weather variables, was modeled using logistic regression. Model predictability was high (73% of variance explained), with temperature and two rainfall-related variables having the most influence on calling frequency. This species of katydid exhibits a highly predictable degree of consistency in calling frequency, and consequently is well suited for use in ecological, distributional and status surveys.
Historical and recent records of both plants and insects are synthesized for uplands along the eastern edge of Maryland's Patuxent River from the edge of the Piedmont south to Jug Bay. This strip is characterized by deep sandy soils found in the Evesboro and Galestown sandy loams soil series. Within this narrow strip there exists a unique flora and fauna adapted to open dry sandy soils and occurring in small remnant patches associated with old sand mining operations and scattered protected areas. We illustrate the uniqueness of these sites using four groups: vascular plants, tenebrionid beetles (Coleoptera: Tenebrionidae), tiger beetles (Coleoptera: Cicindelidae), and bees (Hymenoptera: Apoidea: Anthophila). Within each of these groups, rare species were detected whose populations were locally restricted to this soil type and whose nearest known populations were often hundreds of kilometers away. In addition to documenting the direct conservation importance of these small sandy openings along the Patuxent, we contrast the lack of any indication from vertebrate inventories that this region is unique. The combination of plant and insect inventories appears to be a better means of clarifying a site's importance than does any survey of a single taxonomic group.
Large-scale insect collecting efforts that are facilitated by the use of pan traps result in large numbers of specimens being collected. Storage of these specimens can be problematic if space and equipment are limited. In this study, we investigated the effects of various preservatives (alcohol solutions and DMSO) on the amount and quality of DNA extracted from bees (specifically Halictidae, Apidae, and Andrenidae). In addition, we examined the amount and quality of DNA obtained from bee specimens killed and stored at -80 degrees C and from specimens stored for up to 24 years in ethanol. DNA quality was measured in terms of how well it could be PCR-amplified using a set of mitochondrial primers that are commonly used in insect molecular systematics. Overall the best methods of preservation were ultra-cold freezing and dimethyl sulfoxide, but these are both expensive and in the case of ultra-cold freezing, somewhat impractical for field entomologists. Additionally, dimethyl sulfoxide was shown to have adverse effects on morphological characters that are typically used for identification to the level of species. We therefore recommend that the best alternative is 95% ethanol, as it preserves bee specimens well for both morphological and molecular studies.
Breeding bird populations were sampled between 1954 and 1963, and 1990 and 2000 in ill old-growth forest, the Natural Area of Hungtington Wildlife Forest (HWF), in the Adirondack, Mountains of New York. Trends were compared with data from regional North American Breeding Bird Surveys (BBS) and from a forest plot at Hubbard Brook Experimental Forest, New Hampshire. Trends for 22 species in the HWF Natural Area were negative, eight were positive, and one was zero; 20 were significant. Fifteen of 17 long-distance migrants declined, whereas 7 of 14 short-distance migrants and permanent residents declined. Most (74%) HWF Natural Area species, despite differences in sampling periods and local habitat features, matched in sign of trend when compared to Adirondack BBS routes, 61% matched northeastern BBS routes, and 71% matched eastern United States BBS routes, while 66% matched Hubbard Brook species. The agreement in Population trends Suggests that forest interior birds, especially long-distance migrants, are affected more by regional than local factors. The analysis indicated that bird trends generated from BBS routes may not be as biased toward roads as previously suggested.
An effective approach to species conservation involves efforts to prevent species from becoming threatened with extinction before they become listed as endangered. Standardized monitoring efforts provide the data necessary to estimate population trajectories of many species so that management agencies can identify declining species before they reach the point of endangerment. Species that occur in tidal saltmarshes in North America are under sampled by existing broad-scale monitoring programs. We summarize existing local and regional survey efforts for saltmarsh birds and propose a standardized continental protocol for assessing the status and population trends of birds that breed in saltmarshes in North America. The objective of this proposed survey effort is to create a series of interconnected monitoring efforts that will provide information on the status and the changes in status of terrestrial birds living in saltmarsh systems of North America. We describe detailed fi eld protocols for standardized surveys of saltmarsh birds across North America. We recommend morning point-count surveys with an initial 5-min passive period followed by a period of call broadcast. Surveyors record all individual birds detected (regardless of distance) for all species that are associated with saltmarshes and estimate the distance to each individual bird detected. We provide recommendations for standardizing distance between adjacent survey points, how repeat detections across points are recorded, daily and seasonal timing of surveys, timing of surveys relative to tidal cycles, number of replicate surveys per year, and focal species for this standardized survey effort. Recommended survey protocols include methods that allow estimation of various components of detection probability so that stronger inferences can be made based on trends in count data. We explain why the various survey recommendations are made so that potential participants understand the rationale for various aspects of the survey protocols. We also provide sample data forms and an example of how to fi ll out a data form. These protocols build upon the Standardized North American Marsh-Bird Monitoring Protocols by encouraging those interested in saltmarsh passerines (and other saltmarsh birds) to conduct surveys using a standardized protocol similar to that being used for secretive marsh birds. Standardization of this sort will allow data from surveys focusing on saltmarsh passerines to be easily pooled with data from surveys focusing on secretive marsh birds. Implementing these standardized surveys in saltmarshes across North America will help document regional and continental patterns in distribution and abundance of all birds associated with tidal marshes.
Globally, tidal marshes are found in small pockets or narrow bands totaling only approximately 45,000 square kilometers. The combination of salinity, low floristic and structural complexity, and regular tidal inundation, as well as unpredictable catastrophic flooding, provides a unique selective environment that shapes local adaptations, including those that are morphological, physiological, demographic, and behavioral. Although tidal marshes support a low diversity of nonaquatic vertebrate species, a high proportion of these inhabitants, at least along North American coastlines, are restricted to or have subspecies restricted to tidal marshes. Tidal marshes and their endemic fauna face broad threats from a variety of human-caused environmental changes. Future research should focus on global inventories, intercontinental comparative work, and investigation to determine why almost all presently described endemic taxa appear to be found in North America.
The land area covered by powerline easements in the United States exceeds the area of almost all national parks, including Yellowstone. In parts of Europe and the US, electric companies have altered their land management practices from periodic mowing to extraction of tall vegetation combined with the use of selective herbicides. To investigate whether this alternate management practice might produce higher quality habitat for native bees, we compared the bee fauna collected in unmowed powerline corridors and in nearby mowed grassy fields at the Patuxent Wildlife Research Center (MD). Powerline sites had more spatially and numerically rare species and a richer bee community than the grassy fields, although the difference was less pronounced than we expected. Powerline sites also had more parasitic species and more cavity-nesting bees. Bee communities changed progressively through the season, but differences between the site types were persistent. The surrounding, non-grassland landscape likely has a strong influence on the bee species collected at the grassland sites, as some bees may be foraging in the grasslands but nesting elsewhere. Improving habitat for native bees will help ameliorate the loss of pollination services caused by the collapse of wild and managed honeybee populations. This study suggests that powerline strips have the potential to provide five million acres of bee-friendly habitat in the US if utilities more generally adopt appropriate management practices.