Detectability and Response Rates of Ferruginous Pygmy-Owls

Abstract: Survey techniques that are both reliable and efficient are necessary to accurately estimate population parameters, especially for rare species. Cactus ferruginous pygmy-owls (Glaucidium brasilianum cactorum; hereafter pygmy-owls) have declined in southwestern North America and are surveyed often to comply with federal law. We studied owl responses to broadcasted calls to quantify how detectability and response rates (owls/station/transect) vary with environmental, spatial, temporal, and weather-related factors. We surveyed owls along 392 transects (1,113 km) throughout Sonora, Mexico, including a subset of 14 transects (47.2 km) that we surveyed repeatedly to assess factors that affected response rates. We challenged 17 adults and 23 juveniles that were radiomarked, adults attending 50 occupied nests, and adults attending 6 groups of radiomarked juveniles to respond to broadcasted calls to assess factors that affected detectability. Across Sonora, response time averaged 2.6 ± 0.1 minutes (xM ± SE, n = 520), with 99 ± 0.4% of owls detected in ≤8 minutes; response distance averaged 251 ± 7 m, with 91 ± 1% of owls detected at ≤400 m. Response time decreased by an average of 4 ± 2% and response distance decreased by 12 ± 3 m with each half-month period from early courtship through brooding (P ≤ 0.035). Response time averaged 39 ± 24% faster during morning than midday at occupied nests. Detectability was 1.0 ± 0.0 when surveyors were 100 m from occupied nests and decreased to 0.78 ± 0.10 when surveyors were 500 m from occupied nests. Detectability was higher during incubation, brooding, and natal dispersal (0.89 ± 0.05-1.0 ± 0.0) than during fledgling-dependency (0.50 ± 0.20-0.67 ± 0.19). Response rates of males did not vary from early courtship to brooding (P = 0.84), yet those of females decreased systematically to zero across the same period (P < 0.001). Because detectability of pygmy-owls remains consistently high during nesting, response rates generated from carefully designed surveys can provide reliable estimates of occupancy and abundance.     

Size Bias in Visual Searches and Trapping of Brown Treesnakes on Guam

ABSTRACT The accidental introduction of the brown treesnake (BTS; Boiga irregularis) to the island of Guam after World War II set off a chain of bird, bat, and lizard extirpations. Fortunately, many of the eliminated species have the potential to be restored following population reduction or eradication of the snake. The primary operational tool for population reduction is an effective snake trap, but areas subjected to long-term trapping continue to support BTS, suggesting that some adult snakes are refractory to trapping. We closed a 5-ha area to BTS emigration and immigration and surveyed the population using trapping and visual surveys to determine whether a refractory stratum of adult snakes existed and if trapping was effective for snakes of all sizes. Our surveys included 101 trapping occasions and 109 visual surveys over 309 days, resulting in 2,522 detections of 122 individuals. We detected 44 of 45 supplemented snakes by this intensive sampling effort, which also revealed that trapping was fully effective for snakes >900 mm in snout—vent length (SVL), partially effective for snakes 700–900 mm SVL, and totally ineffective for smaller juveniles (350–700 mm SVL). Visual searching was effective for snakes of all sizes. As BTS mature at approximately 950-1, 050 mm SVL, continuous trapping should suffice to eliminate recruitment in the absence of immigration. Immigration or inadequate effort is most likely responsible for the persistence of BTS in areas subject to long-term trapping. Thus, current efforts to capture trap-refractory adult snakes with alternate control tools are less likely to be successful than immigration barriers alone or in combination with elevated capture effort.     

Gut content and stable isotope analyses provide complementary understanding of ontogenetic dietary shifts and trophic relationships among fishes in a tropical river

1. Despite widespread recognition of the role of body size in fish trophic ecology, little attention has been focused on this issue in isotopic studies, particularly in tropical systems. 2. We used analyses of stomach contents and stable isotopes to examine size‐related shifts in diet in a terapontid fish assemblage in the Australian wet–dry tropics. Stomach content analysis identified substantial ontogenetic dietary shifts in all species, corresponding to changes in body size–isotope trajectories for two species. Shifts away from relatively specialised diets of heavily ¹³C‐depleted insect larvae to consumption of a range of items across multiple basal carbon sources appeared to be the proximate cause of observed isotopic changes. 3. Allochthonous organic matter in the form of C3 riparian vegetation was particularly important to smaller terapontids before larger fish shifted to a broad range of dietary items and similarly broad range of basal carbon sources. 4. While there was general agreement between δ¹³C and stomach content analysis, there was minimal concurrence between the latter and δ¹⁵N isotopic derivation of estimates of trophic position. Due to factors such as omnivory, isotopically overlapping basal sources and uncertainties about rates of isotopic fractionation in both predator and prey species, stomach content analysis provides an essential complement to isotopic methodologies in tropical systems. 5. Given that basal sources supporting any individual species can change markedly with ontogeny, consideration of intraspecific, size‐related variation is necessary in isotopic studies of food web structure.     

Phylogenetic revision of the North American Asidini (Coleoptera: Tenebrionidae)

The asidine darkling beetles (Coleoptera: Tenebrionidae: Asidini) are a morphologically diverse tribe of flightless tenebrionids found in many arid and sub‐arid habitats around the world. The 260 currently described North American species are contained in 27 genera, all of which are restricted to the western half of the continent. Evolutionary relationships within and between the North American Asidini (Coleoptera: Tenebrionidae) genera were reconstructed using partial sequences of mitochondrial cytochrome c oxidase I (COI) (660 bp) and nuclear ribosomal 28S (D2 region) (492 bp), and 100 phenotypic characters for 50 North American asidine species, representing 20 of the 27 currently described genera and 1 new genus. Species from two additional tenebrionid tribes (Branchini and Coniontini) and the South American asidine genus Cardigenius were chosen as outgroups. Analyses were performed using maximum parsimony and Bayesian inference methods. Clade support was inferred based on the posterior probability distribution of tree topologies, nonparametric bootstrap analysis, and partitioned Bremer support indices. The generic classification of the North American Asidini is revised based on the results, with ten genera recognized. Seven current genera: Craniotus LeConte, Heterasida Casey, Litasida Casey, Microschatia Solier, Pelecyphorus Solier, Philolithus Lacordaire, Stenomorpha Solier, are redescribed, and Ardamimicus Smith gen.n ., Ferveoventer Smith gen.n . and Micrasida Smith gen.n . are described, including Ardamimicus cognatoi Smith sp.n ., Ferveoventer browni Smith sp.n . and Micrasida obrienorum Smith sp.n . Twenty current genera are treated as subgenera pending further analyses: Philolithus Lacordaire with subgenera Glyptasida Casey, Gonasida Casey, Herthasida Wilke and Tisamenes Champion; Pelecyphorus Solier, with subgenera: Astrotus LeConte, Parasida Casey (= Plesiasida nom.n ), Poliorcetes Champion, Sicharbas Champion, Stenosides Solier, Ucalegon Champion and Zaleucus Champion, and Stenomorpha Solier with subgenera Asidina Casey, Asidopsis Casey, Bothrasida Casey, Megasida Casey, Notiasida Casey, Platasida Casey, Pycnomorpha Motschulsky, Stethasida Casey and Trichiasida Casey; all stat.rev .     

Of glaciers and refugia: a decade of study sheds new light on the phylogeography of northwestern North America

Glacial cycles have played a dominant role in shaping the genetic structure and distribution of biota in northwestern North America. The two major ice age refugia of Beringia and the Pacific Northwest were connected by major mountain chains and bordered by the Pacific Ocean. As a result, numerous refugial options were available for the regions taxa during glacial advances. We reviewed the importance of glaciations and refugia in shaping northwestern North America’s phylogeographic history. We also tested whether ecological variables were associated with refugial history. The recurrent phylogeographic patterns that emerged were the following: (i) additional complexity, i.e. refugia within refugia, in both Beringia and the Pacific Northwest; and (ii) strong evidence for cryptic refugia in the Alexander Archipelago and Haida Gwaii, the Canadian Arctic and within the ice‐sheets. Species with contemporary ranges that covered multiple refugia, or those with high dispersal ability, were significantly more likely to have resided in multiple refugia. Most of the shared phylogeographic patterns can be attributed to multiple refugial locales during the last glacial maximum or major physiographic barriers like rivers and glaciers. However, some of the observed patterns are much older and appear connected to the orogeny of the Cascade‐Sierra chain or allopatric differentiation during historic glacial advances. The emergent patterns from this review suggest we should refine the classic Beringian‐southern refugial paradigm for northwestern North American biota and highlight the ecological and evolutionary consequences of colonization from multiple refugia.     

Diversification of coordination patterns during feeding behaviour in cheiline wrasses

Successful fish feeding often requires the coordination of several complex motor and sensory systems to ensure that food is accurately detected, approached, acquired, and consumed. In the present study, we address feeding behaviour as a coordinated set of multiple, facultatively independent, anatomical systems. We sought to determine whether the patterns of interaction between trophic, locomotor, and oculomotor systems are associated with changes in morphology and ecology within a closely-related, but trophically divergent, group of fishes. We present a quantitative kinematic analysis of skull motion, locomotor behaviour, and oculomotor responses during feeding to assess coordination in three functional systems directly involved in feeding. We use coordination profiles to depict the feeding behaviours of three carnivorous coral reef fishes of the tribe Cheilinini in the family Labridae (the wrasses): Cheilinus fasciatus (a slow-swimming predator of benthic invertebrates), Epibulus insidiator (a slow-stalking predator with extraordinary jaw protrusion), and Oxycheilinus digrammus (a fast-attack predator). Differences were detected in several variables relating to jaw, body, fin, and eye movements. Overall patterns of coordination were more similar between E. insidiator and O. digrammus , which are capable of capturing elusive prey, than between C. fasciatus and E. insidiator , which are the two most closely-related species among the three. Evidence for the evolution of coordination patterns among cheiline fishes suggests that the sensory-motor systems involved in processing stimuli and coordinating a physical response during feeding have changed considerably, even among closely-related species.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 289–308.     

Morphological Transformation of Rat Embryo Cells by the Combined Action of 3-Methylcholanthrene and Rauscher Leukaemia Virus

RAT embryo cells infected with either CF-1 or Rauscher C-type RNA murine leukaemia virus, when treated with diethylnitrosamine (DENA), undergo morphological transformation and become aneuploid¹. Untreated cells and cells treated with either virus or chemical alone do not transform. We describe here a similar effect of 3-methylcholanthrene (3 MC) on rat cells infected with Rauscher leukaemia virus.     

Response of Brown Treesnakes to Reduction of Their Rodent Prey

ABSTRACT Trapping brown treesnakes (Boiga irregularis; BTS) with live-mouse (Mus domesticus) lures is the principal control technique for this invasive species on Guam. Lure-based trapping is also used on other islands as a precaution against undetected arrivals and in response to verified BTS sightings. However, the effectiveness of lure-based trapping on other islands is questionable, as it has yielded no BTS despite other evidence of their presence. Some evidence suggests that high rodent numbers may interfere with BTS control. To test the relationship between rodent abundance and snake trappability, we conducted a controlled, replicated field experiment incorporating a rodenticide treatment during a BTS mark-recapture study. Using open population modeling in Program MARK, we estimated BTS apparent survival and recapture probabilities. Rodent reduction increased BTS recapture probabilities by 52–65% in 2002 and 22–36% in 2003, and it decreased apparent survival by < 1% both years. This appears to be the first published instance of manipulating wild prey to influence snake behavior. Rodent reduction may enhance detection and control of BTS with traps on Guam and other islands. It may also amplify the effectiveness of oral toxicants against BTS.     

What determines conditionality in ant–Hemiptera interactions? Hemiptera habitat preference and the role of local ant activity

Abstract.  1. This paper describes spatial variation in density of a mutualist Hemiptera, and attempts to elucidate an understanding of the spatial variation in conditionality of its mutualism with ants.
2. Aggregations of the membracid treehopper, Campylenchia sp., occurred more frequently, and with higher number of individuals, in isolated trees as compared with their occurrence in the same tree species in wooded patches.
3. Using treehopper aggregations as the level of replication, there was a habitat × ant presence interaction associated with colony survival time. However, when the median survival time of all aggregations within each tree was used, only an additive effect of both habitat type and ant presence were apparent. This suggests that treehopper aggregations in some isolated trees experienced more benefit from ant presence than other trees.
4. The ant:treehopper ratio averaged over each tree was correlated with effect of ant presence on survivorship (survival time without ants/survival time with ants). Therefore, conditionality in the ant–membracid mutualism appears related to ant attendance level at the scale of individual trees.
5. Ant attendance at treehopper aggregations in isolated and matorral trees did not differ, and therefore there is no clear mechanism by which ants create the contrast in treehopper densities between the two habitat types.
6. The main force shaping initial treehopper densities in the two habitats is likely plant quality. Results suggest that growing situation (or more specifically plant health) is likely a good predictor of membracid density, while general ant activity within a tree is the best indicator of interaction strength.