Migration and wintering sites of Pelagic Cormorants determined by satellite telemetry

ABSTRACT Factors affecting winter survival may be key determinants of status and population trends of seabirds, but connections between breeding sites and wintering areas of most populations are poorly known. Pelagic Cormorants (Phalacrocorax pelagicus; N= 6) surgically implanted with satellite transmitters migrated from a breeding colony on Middleton Island, northern Gulf of Alaska, to wintering sites in southeast Alaska and northern British Columbia. Winter locations averaged 920 km (range = 600–1190 km) from the breeding site. Migration flights in fall and spring lasted ≤5 d in four instances. After reaching wintering areas, cormorants settled in narrowly circumscribed inshore locations (～10‐km radius) and remained there throughout the nonbreeding period (September– March). Two juveniles tagged at the breeding colony as fledglings remained at their wintering sites for the duration of the tracking interval (14 and 22 mo, respectively). Most cormorants used multiple sites within their winter ranges for roosting and foraging. Band recoveries show that Pelagic Cormorants in southern British Columbia and Washington disperse locally in winter, rather than migrating like the cormorants in our study. Radio‐tagging and monitoring cormorants and other seabirds from known breeding sites are vital for understanding migratory connectivity and improving conservation strategies for local populations.     

Digital Photography Improves Consistency and Accuracy of Bat Counts in Hibernacula

ABSTRACT The size and distribution of measurement errors associated with major techniques for estimating numbers of hibernating bats are unstudied, although this is the principle method of enumerating several endangered bat species. However, decisions concerning the listing status of a species under the Endangered Species Act require consistent and accurate estimation of population size and trends. Recent advances in digital photography have improved the ability to produce a quantitative record of the numbers of bats in hibernacula. We surveyed clusters of Indiana bats in a hibernaculum and compared results from counts of digital photographs of clusters to results from 4 variations of visual estimation. We counted bats in photographs using Geographic Information System digitization over the photograph. Total counts from 2 sets of photographs varied by <1.5%. Nonphotographic estimation techniques varied from 76% to 142% of counts from photographs for clusters for which estimation (rather than counting) was used. Where feasible, photography can improve status and trend information for species of concern, permitting more timely and specific management actions.     

Floral biology and pollination strategy of seven Tacca species (Taccaceae)

We investigated the floral characteristics, floral biology and floral visitors of the six Bornean Tacca species: T. bibracteata (only floral characteristics), T. borneensis, T. havilandii, T. leontopetaloides, T. palmata and T. reducta, and T. cristata from Peninsular Malaysia. All species are protogynous with pollen strings extruded post flower opening. Blooming of all species started from dawn except for T. leontopetaloides which flowered from dusk. While T. borneensis, T. cristata, T. havilandii, T. leontopetaloides and T. reducta are facultatively autogamic as the pollen/ovule ratios (P/O ratios) were low, T. bibracteata is facultatively xenogamic as its P/O ratio was higher. Four species (T. borneensis, T. cristata, T. havilandii and T. reducta) were tested for autonomous self-pollination but all failed to set fruit. Manual self- and cross-pollination treatments of T. borneensis, T. cristata and T. havilandii showed reduced fruit set and seed set. In contrast, T. reducta was highly self-compatible. The showy bracts and bracteoles of T. borneensis are needed to guarantee pollination success but is not so in the other species investigated. Tacca are pollinated by two pollination guilds of female midges: two species of Forcipomyia (Lasiohelea) and Culicoides hinnoi. The floral biology and mating system of Tacca species indicate that most fruits and seeds were produced in samples resulting from natural pollination.     

Roost sites of chimney swift (Chaetura pelagica) form large‐scale spatial networks

Several biodiversity‐centered metrics exist to quantify the importance of landscape and habitat features for conservation efforts. However, for species whose habitat use is not quantified by these metrics, such as those in urban areas, we need a method to best identify features for targeted conservation efforts. We investigated the use of social network analysis (SNA) to identify and quantify these critical habitat features. We used SNA to identify network existence in chimney swift (Chaetura pelagica) roost usage, quantify the importance of each roost site, and evaluate the impact of the loss of key sites. We identified a network consisting of ten chimney swift roosts in southern Nova Scotia, Canada, and found that 76% of swifts used more than one roost throughout the breeding season. We also isolated three key (most connected) roost sites. We evaluated the effect of loss of these key sites on the network by using a Wilcoxon‐Pratt signed‐rank test and by analyzing the structure of the subsequent network. We found that connections between roosts and the structure of the network were significantly affected by the loss of these key sites. Our results show that SNA is a valuable tool that can identify key sites for targeted conservation efforts for species that may not be included in conservation efforts focused purely on biodiversity.     

Histomorphology of the glans penis in Vespertilionidae and Phyllostomidae species (Chiroptera,Mammalia)

The penises of bats are taxonomically distinctive in size and shape. In addition, they are variable in microscopic anatomy, indicating that histomorphological studies of copulatory organs of bats may help understanding their successful reproductive strategies. We studied adult males of 13 species of vespertilionid and phyllostomid bats. Both families exhibited the basic structure of the vascular penis of mammals: the hydrostatic elements of the corpora cavernosa and the corpus spongiosum surrounding the urethra, as well as accessory cavernous tissue. Variation in the position and amount of the tissues were observed in these families. Vespertilionid bats have a small glans penis with abundant accessory cavernous tissue on the prepuce and a highly variable baculum. The baculum varied in size and morphology, even among congeneric species, such as the three Lasiurus species and the two Myotis species. Phyllostomid species possess no bacula, but vascular structures are present to produce penile stiffening, particularly on the glans. Variation in the microscopic anatomy of the phyllostomid prepuce was observed, for example, Artibeus species had accessory cavernous tissue surrounded by a tunica albuginea, but Carollia perspicillata had two bundles of striated musculature and some adipose tissue; abundant pigments were present in the prepuce of most species.     

Predictive Occurrence Models for Bat Species in California

Abstract: The ability to accurately predict the potential occurrence of species of management concern is useful for wildlife managers, particularly for those whose management activities involve large areas where sampling is difficult due to logistical or financial constraints. During the summers of 2002 and 2003, we used mist nets to capture bats (Myotis yumanensis, M. californicus, M. evotis, M. thysanodes, Eptesicus fuscus, Lasionycteris noctivagans, Tadarida brasiliensis, Antrozous pallidus, Lasiurus borealis, and Lasiurus cinereus) in Whiskeytown National Recreation Area in north-central California, USA. We used landscape-scale variables, logistic regression, and Akaike's Information Criterion (AIC_c) to model species distributions and produce spatially discerning predictive occurrence maps. We developed a priori models that we used to determine which landscape-scale variables best discriminated between capture sites and non-capture sites. The odds of capturing a bat were 3.3 greater when total edge increased by 10,000 m, whereas for Yuma myotis (Myotis yumanensis), the odds of predicting presence were 0.2 greater when distance to lakes and ponds decreased by 2,000 m. Elevation was important in predicting the distribution of silver-haired bats (Lasionycteris noctivagans) and big brown bats (Eptesicus fuscus). Increasing elevation by 400 m decreased the odds of capturing a silver-haired bat by 0.1 and a big brown bat by 0.4. Classification accuracy for our models ranged from 80.9% for all bat species combined to 72.3% for Yuma myotis and silver-haired bats. Predictive occurrence models can be valuable to bat conservation efforts because they provide spatial data important for evaluating the effects of management activities on species distributions.     

A comparison of two bat detectors: which is most likely to detect New Zealand’s Chalinolobus tuberculatus?

ABSTRACT

The presence of bat species is commonly determined by placing acoustic bat detectors that record bat echolocation calls in the habitat they are likely to use. Detection rates are affected by variables including type of detection unit used. We compared detection rates of long-tailed bat (Chalinolobus tuberculatus) echolocation calls between two types of automated bat detectors: Wildlife Acoustics SMZC Zero Crossing Bat Recorders (ZC), and Frequency Compression Automated Bat Monitoring units (FC) produced by New Zealand’s Department of Conservation. Units were placed in locations where bats were known to be present, but not all detected bats. The median number of bat passes recorded by FC units over 10 nights was 20 compared with a median of 3 bat passes for ZC units. ZC units also detected bats over significantly fewer nights than FC units. These results suggest FC units are more sensitive and therefore better to use where long-tailed bats are expected to be at low abundance or only present infrequently. Because of inconsistencies in detection rates, we recommend the use of only one model of the detector within a monitoring project. Our data also suggests that surveys should take place over long periods to maximise likelihood of detecting bats, if present.     

Bat boxes in urban bushland are associated with inflated activity of an urban generalist bat,but not an altered community

Bat boxes are often installed as substitute habitats to offset the loss of large, hollow-bearing trees. However, emerging evidence suggests that they are failing to achieve intended conservation outcomes as they only support generalist species. Despite these concerns, the effect of bat boxes on the dynamics of bat communities remains understudied. We assessed the bat community in reserves where bat boxes had been installed in comparison with reserves where they had not using ultrasonic surveys in 16 small bushland reserves throughout Sydney, Australia. Reserves containing bat boxes and those without had comparable species diversity and composition; however, the activity of the dominant species, Gould's wattled bat (Chalinolobus gouldii), was significantly higher at sites with bat boxes. Species that commonly forage in open vegetation, including C. gouldii, were significantly positively associated with sites that had bat boxes. Occupation of boxes by bats was not recorded in the study due to limited information on their locations, so further research is required to understand the direct effects of boxes and the bats that occupy them on the bat community. If bat boxes continue to be recommended as a biodiversity offset, a greater understanding of the potential impact they have on altered competitive relationships and community dynamics is essential.