Predictive Model of Habitat Suitability for the Marbled Murrelet in Western Washington

Abstract: The marbled murrelet (Brachyramphus marmoratus) is a small Pacific seabird with a breeding range that extends from the Aleutian Islands to central California. Throughout most of its breeding range, it uses mature and old-growth coniferous forests as nesting habitat. Although most murrelets seem to nest within 60 km of the coast, occupied nesting habitat has been identified as far as 84 km from the ocean in Washington state. Due to the extensive inland distances within which birds are known to breed, the area requiring surveys to identify breeding sites can be enormous. Therefore, the standard 2-year survey protocol can be expensive and time-consuming for forest management agencies and companies to administer. We developed a logistic regression model to determine whether a suite of forest structural characteristics could be used to reliably predict occupancy of a forest patch by marbled murrelets. We tested the performance of the final model using cross-validation procedures and a sample of independent sites. We used 50 sites surveyed for marbled murrelets to estimate the model, and 48 independent sites were available to test model performance. All 50 sites were on private forestland owned by Rayonier located in the western lowlands of Olympic Peninsula within the Sitka spruce and western hemlock transition zones. We sampled forest habitat at each site, and we collected information on 15 explanatory variables. The best-fitting logistic regression model contained variables that measured number of canopy layers (P<0.001, approx. F test) and mistletoe (Arceuthobium sp.) abundance (P = 0.031, approx. F test). The model misclassified 2 of 33 (94% correct) unoccupied sites as occupied using a classification cut-off (c) of c=0.25. In the other direction, under cross-validation the final model misclassified 2 of 17 (88% correct) occupied sites as unoccupied. On a test of the model against an independent sample, using a classification cut-off value of c = 0.25, the final model correctly classified 36 of 48 sites (75% correct). The final model misclassified 3 of 31 occupied sites as unoccupied (90% correct). Use of predictive models could greatly reduce the amount of forest that requires surveys by screening out those sites with little probability of use and by focusing remaining effort on higher probability sites, resulting in a higher likelihood of identifying occupied sites and thereby more efficiently conserving marbled murrelet nesting habitat.     

Northern Goshawk Habitat: an Intersection of Science,Management, and Conservation

Abstract: We responded to the claim by Greenwald et al. (2005) that the management recommendations for the northern goshawk in the Southwestern United States (MRNG; Reynolds et al. 1992), a food web-based conservation plan that incorporated both northern goshawk (Accipiter gentilis) and multiple prey habitats, may be inadequate to protect goshawks. Greenwald et al. (2005) based this claim on their review of 12 telemetry studies of goshawk habitat selection and 5 nontelemetry studies of the effects of vegetation structure at the home range scale on goshawk nest occupancy and reproduction that appeared after the 1992 publication of the MRNG. Greenwald et al. (2005) summarized their review as showing that 1) goshawks were habitat specialists limited to forests with mature and old-growth structures including large trees, high canopy cover, multiple canopy layering, and abundant woody debris; 2) habitats were not selected on the basis of prey abundance and, therefore, managing for prey habitats diluted goshawk habitats; and 3) selection for openings, edges, and habitat diversity was inconclusive. Our review found that when the studies' respective authors pooled their radiotagged goshawks there were weak to strong selections for old forest structures. However, the studies also documented extensive variation in use of vegetation types and structures by individual goshawks; some avoided openings, edges, young forests, and old forests, whereas others selected for these characteristics. Additionally, by virtue of their wide geographic distribution, the studies showed that the focal populations themselves occurred in a variety of forest types, some with large structural differences. We found no evidence in Greenwald's et al. (2005) review that the MRNG are inadequate to protect goshawks. Rather, the studies reviewed by Greenwald et al. (2005), as well as many studies they missed, supported the MRNG. The suggestion of inadequacy by Greenwald et al. (2005) appeared rooted in misunderstandings of goshawk habitats described in the MRNG, a discounting of the extent of variation in vegetation structural and seral stages used by goshawks, a limited understanding of the extent to which prey limits goshawks, a failure to recognize the dynamic nature of forests, and an incomplete review of the literature. We believe the MRNG are adequate because they maximize the sustainable amount of mature and old forests in goshawk home ranges and specify the kinds and intermixtures of prey habitats within home ranges. Implementation of MRNG should reduce the likelihood that the availability of vegetation structures suited to goshawk nesting and foraging, as well as abundance and availability of prey, will limit goshawk nest occupancy and reproduction.     

Flow-related patterns in abundance and composition of the fish fauna of a degraded Australian lowland river

1. A 7‐year study was conducted in three hydrologically distinct sections within the highly regulated, lowland Campaspe River to investigate the influence of hydrology on temporal and spatial patterns in fish composition, abundance and recruitment. One section had 6 months, one section 2 months and one section no months of increased flow due to storage releases. The fish fauna of the less regulated, nearby Broken River served as a reference to which that of the Campaspe River was compared for the last 3 years of the study to allow insight into the relative effects of hydrology, barriers to movement and other environmental characteristics. The study included one high‐flow year, a moderate‐flow year and five low‐flow years. 2. A total of 16 fish species – 10 native and six alien – were caught in the Campaspe River, although of the native species, only three are considered to have self‐sustaining populations. The remaining species are either itinerants or a result of stocking. Alien species comprised approximately 64% of the total biomass of all fish caught. 3. Overall composition of the fish fauna did not differ significantly by year, but did by section of river. Species richness and the abundance of most of the dominant species also differed significantly by river section, but there was little inter‐annual variation in the abundance of any species, except for European perch and for common carp; the latter showing an increase in abundance following a high‐flow event during the spring of 2000 as a result of recruitment. 4. Overall faunal composition was not influenced by hydrology. However, multiple regression indicated that species richness, abundance of the dominant species and abundance of young‐of‐year (YOY) of golden perch, European perch and common carp all were influenced significantly by hydrological variables. The nature of the relationships was dependent on river section and hydrological season (‘winter’ or ‘spring/summer’). Of note was the result that the total abundance of fish and that of YOY common carp were significantly positively related to the number of spells above the threshold for movement upstream through the lower two weirs in the Campaspe River. Only one significant relationship between hydrological and fish‐related variables was found for the upper river section, whereas seven and five were found for the lower and middle sections respectively. 5. Comparisons with fish collected in the Broken River over 3 years suggest that the fauna of the Broken River is in a more natural state than that of the Campaspe River. Since the two rivers do not differ substantially in water quality, and since both contain significant weirs, which act as barriers to movement of fish, flow regulation is most likely to be the major reason for the poor state of the fauna in the Campaspe River.     

Anthropogenic causes of the western Steller sea lion Eumetopias jubatus population decline and their threat to recovery

• 1 The western Steller sea lion Eumetopias jubatus population has experienced a chronic decline since the 1960s. The causes are likely multifactorial and a combination of anthropogenic and natural factors. A draft revised recovery plan for the Steller sea lion has been published by the US National Marine Fisheries Service, listing both anthropogenic and natural factors that may have contributed to the observed decline or which may be a threat to the recovery of the western Steller sea lion population. The purpose of this review is to consider the anthropogenic threats to this stock.
• 2 Anthropogenic sources of mortality include fisheries competition resulting in nutritional stress, mortality incidental to commercial fisheries (i.e. fisheries by‐catch), subsistence hunts, legal and illegal shooting, commercial hunts, anthropogenic‐related contamination, and research‐induced mortalities.
• 3 We present evidence that the following anthropogenic factors likely contributed to the decline of the western Steller sea lion population over the last 40 years: (i) mortality incidental to commercial fisheries (i.e. by‐catch); (ii) commercial hunting of western Steller sea lions; and (iii) legal and illegal shooting; whereas the subsistence hunts for western Steller sea lions and mortality incidental to research were not likely to be contributors to the observed decline.
• 4 Further, we present evidence that the following can be excluded as significant anthropogenic threats to the recovery of the western Steller sea lion population: (i) mortality incidental to commercial fishing; (ii) legal and illegal shooting; (iii) commercial hunts of Steller sea lions; (iv) subsistence hunting; and (v) mortality incidental to research.
• 5 Competition with fisheries resulting in nutritional stress, and the potential impacts of contaminants, are two anthropogenic factors that should continue to be a priority for the various organizations currently doing research on this population.

     

Characterization of polymorphic microsatellites in the castration parasite plant‐ant Allomerus octoarticulatus cf. demerarae (Formicidae: Myrmicinae)

Fifteen microsatellite loci were isolated from the Peruvian tropical plant‐ant Allomerus octoarticulatus cf. demerarae (Hymenoptera: Myrmicinae) and their polymorphism was characterized. High levels of within‐population variation were observed at most loci, with number of alleles ranging from one to 21, and heterozygosity from 0 to 1 per population sample. Cross‐species amplification of these loci was also tested in one other species of the ant genus Allomerus (Allomerus decemarticulatus), displaying similar life history.     

Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis and Oestrus ovis

Abstract. Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis De Geer (Diptera: Gasterophilidae) and Oestrus ovis (L.) were studied by scanning electron microscopy. Two types of trichoid sensilla, two types of coeloconic sensilla and a pit sensillum were present on the thoracic and abdominal segments of G. intestinalis larvae. Sensilla on larvae of O. ovis were similar although only one type of trichoid sensillum was present. Total number of sensilla were higher for O. ovis than for G. intestinalis (248 v . 214). Variation in numbers of sensilla is consistent with the concept that increasing numbers of sensilla are associated with increasingly complex searching behaviour required to locate suitable habitats for development.     

Dependence of the Post-Illumination Burst of CO2 on Temperature, Light, CO2, and O2 Concentration in Wheat (Triticum aestivum)

The effect of environmental factors on the post-illumination burst of CO₂ (PIB) and O₂ inhibition of apparent photosynthesis (APS) in wheat (Triticum aestivum L.) was studied in an open gas exchange system utilizing the mathematics of non-steady-state systems. Two components of inhibition by O₂ are suggested: one is caused by photorespiration as measured from the maximum rate of the PIB, and the second is direct inhibition as taken as APS_2%O2— (APS_x%O2+ PIB_x%O2) where X is the oxygen concentration. A primary PIB which occurred from 16–28 s after the darkening of the foliage was attributed to photorespiration. No primary PIB was observed at 2% O₂. At a CO₂ concentration of 100 μ/1 in the atmosphere (about 2.5 μM based on leaf intercellular concentration) and at 30°C and 145 nE/cm² nE/cm²·s, APS decreased curve-linearly with increasing O₂ and reached an O₂ compensation point of 560 μM (48% by volume), above which there was a net loss of CO₂ in the light. The PIB increased with increasing O₂ and became saturated at about 500 μM O₂ but decreased above 900 μM O₂. Direct inhibition of photosynthesis by O₂ increased with increasing O₂ concentration. Decreasing CO₂ concentration had an effect on the magnitude of the PIB similar to that of increasing O₂. At 30°C and 21% O₂, the PIB increased with decreasing CO₂ down to the CO₂ compensation point (I) of 1.4 μM (47 μM/l). Below Γ, both PIB and CO₂ evolution into the air in the light (at 21% O₂) increased and then decreased at CO₂ below 0.8 μM. The ratio of the PIB to APS_{2% o} O₂ increased linearly with increasing O₂/CO₂ ratio where O₂ was held constant at 21% and CO₂ was varied from 1.4 to 8.5 μM, while direct inhibition of photosynthesis expressed as a proportion of APS_2%O2 remained constant over this range. At low CO₂ concentration photorespiration as estimated by the PIB is the major part of O₂ photosynthesis, while at atmospheric CO₂ levels, direct inhibition is the major component. The PIB and APS at 2% and 21% O₂ increased hyperbolically with increasing irradiance and all became light-saturated at about 65 nE/cm₂ s. The percentage total O₂ inhibition of photosynthesis remained constant with increasing irradiance as did the relative contribution of direct O₂ inhibition or photorespiration (PIB) to total O₂ inhibition. The PIB and APS at 21% O₂ had similar temperature optima of 30°C when experimental conditions were adjusted to provide a constant internal O₂/CO₂ solubility ratio at varying temperatures. However, with a constant external CO₂ concentration, the temperature optimum for the PIB shifted upward to 35°C while that for APS at 21% O₂ remained at 30°C, which may be due to an increased O₂/CO₂ concentration in the leaf with increasing temperature.     

The systematic relationships of the snake genus Anomochilus

Phylogenetic analysis of 38 skeletal characters, 12 muscular characters and 15 visceral characters in 17 major snake clades plus Anomochilus suggests that Anomochilus is the sister taxon of all other living alethinophidian snakes. However, skeletal, muscular and visceral character sets analysed separately or in pairs give four groups of nonconcordant tree topologies. Based on the cladogram derived from the total evidence, two families are erected to prevent the existing family Uropeltidae from becoming paraphyletic: Anomochilidae, for the Malaysian and Indonesian genus Anomochilus , and Cylindrophiidae, for the Sri Lankan, Southeast Asian and Indonesian genus Cylindrophis and the Upper Eocene fossil Eoanilius.     

The influence of host distribution, sex, and size on the level of parasitism by Itoplectis conquisitor (Hymenoptera: Ichneumonidae)

Abstract. 1. Parasitism of the bagworm, Thyridopteryx ephemeraeformis Haw. (Lepidoptera: Psychidae), on red cedar was studied at Manassas, Va., U.S.A.
2. Fifteen parasitoids, five of which were hyperparasitoids, attacked the pupal stage of the bagworm. The Ichneumonid Itoplectis conquisitor alone accounted for 58% of the parasitized bagworms.
3. Parasitism by I conquisitor (Say) was inversely related to host size, but independent of host distribution within a tree. Male bagworms experienced disproportionately higher levels of parasitism than females. We conclude that it is small size that renders bagworms susceptible to parasitism rather than sex per se.
4. Ovipositor lengths of I.conquisitor were insufficient to penetrate the larger bagworm hosts (>57 mm); and in fact, as bagworm size increased, the proportion of the I.conquisitor population capable of penetrating the pupa declined abruptly. We suggest that the mechanical difficulties with oviposition, and perhaps the defensive capabilities of larger hosts, are responsible for the relationship between host size and per cent parasitism.
5. I.conquisitor could be an important selective agent for bagworm size at pupation, but it is not likely to act as a significant control agent of population density.