A synopsis of suggested approaches to address potential competitive interactions between Barred Owls (<Emphasis Type="Italic">Strix varia</Emphasis>) and Spotted Owls (<Emphasis Type="Italic">S. occidentalis</Emphasis>)

The conservation of Spotted Owl (Strix occidentalis) populations has been one of the most controversial and visible issues in United States conservation history. Coincident with declines in Spotted Owl populations over the last three decades has been the invasion of Barred Owls (Strix varia) throughout the range of the Northern Spotted Owl (S. o. caurina) and into the range of the California Spotted Owl (S. o. occidentalis). This invasion has confused the reasons behind recent Spotted Owl declines because anecdotal and correlative information strongly suggests that Barred Owls are a new factor influencing the declines. There is great uncertainty about all aspects of the invasion, and this has sparked discussion about appropriate management and research responses regarding the effects of this invasion on Spotted Owls. We present a set of possible responses to address the issue, and we discuss the relative merits of these with regard to their efficacy given the current state of knowledge. We recommend that research specifically aimed at learning more about the interspecific relationships of these two owls throughout the range of sympatry should begin immediately. Approaches that seem unlikely to be useful in the short-term either because they do not facilitate knowledge acquisition, are relatively costly, or would be technically less feasible, should not be considered viable at this time. We believe the consequences of the invasion are potentially dire for the Spotted Owl and that research and management actions, including the use of adaptive management, are required to inform the near- and long-term decision-making process for conservation of Spotted Owls.     

Dietary protein hydrolysate and trypsin inhibitor effects on digestive capacities and performances during early-stages of spotted wolffish: suggested mechanisms

Growth rate is dependent upon adequate provision of amino acids especially in newly-hatched fish which experience very high growth rate. The replacement of a fraction of protein content by partially hydrolyzed (pre-digested) proteins was carried out and the digestive capacities and performances of larval/juvenile spotted wolffish (Anarhichas minor) were measured. The goal of this study was to verify whether the scope for growth is principally dictated by the proteolytic capacity of the digestive system by examining the effect of protein hydrolysates (PH) and trypsin inhibitor dietary inclusion on protein digestion/assimilation capacities, growth and survival. Four experimental diets were examined: C (control) I (supplemented with 750 mg/kg soybean trypsin inhibitor (SBTI)) H (supplemented with 20% PH) and HI (supplemented with 20% PH and 750 mg/kg SBTI). Protein hydrolysate supplementation gave significantly higher body mass than control at day 15 post-hatching. Unexpectedly, at day 30 and 60, fish administered diet HI (containing trypsin inhibitor) were heavier than the other groups. Suggested mechanisms are presented and discussed. The main conclusions of this study are that wolffish larval stage lasts roughly 15 days and that juvenile growth is linked to proteolytic capacity, but also very likely to absorption capacity of peptides and amino acids.     

Biometry based ageing of nestling Indian Spotted Owlets ( Athene brama brama)

Biometric analysis helps in sex differentiation, understanding development and for studies of avian biology such as foraging ecology, evolutionary ecology, and survivorship. We suggest that biometry can also be a reliable, practical and inexpensive tool to determine the age of nestlings in the field by non-invasive methods. As an example we studied the biometry of wing, culmen, talon, tarsus and body mass of nestling southern Indian Spotted Owlets (Athene brama brama). Based on the growth pattern analysis using logistic growth model, discriminant analysis and CHAID (Chi-squared Automatic Interaction Detection) based decision tree, we show that biometry of nestling Spotted Owlets is an easy, reliable and inexpensive method to determine nestling age and to assess growth rate and relative nutritional status. These biometric parameters also allow us to predict their ability to initiate first flight from the nest site. This method is described here for the first time and we postulate that such charts can be devised for other avian species as well, so as to assist conservation biologists and bird rescuers.     

农田林网条件下大斑啄木鸟夏季和冬季日间行为模式

2005年7月至2008年1月,利用目标动物取样法对内蒙古乌拉特前旗地区农田林网中大斑啄木鸟(Picoides major)夏季和冬季的日间行为模式进行了分析.结果发现,大斑啄木鸟不同行为的活动次数差异极为显著,主要活动是觅食啄食;夏季具午间休息习性,日间行为节律明显,而冬季没有午休习性,日问行为节律不明显;不同性别大斑啄木鸟之间的日间行为差异不显著,但大斑啄木鸟在不同季节的日间行为差异极为显著,夏季活动时间明显长于冬季.     

New techniques and findings in the study of a candidate allelochemical implicated in invasion success

Allelopathy has been hypothesized to promote the success of invasive plants. Support for the role of allelopathy in invasions has emerged from research on the candidate allelochemical (?)‐catechin, which is secreted by spotted knapweed. Here we describe new methods to quantify catechin in liquid and soil. With a new technique, we assayed catechin production by individual plants in liquid media and found levels up to two orders of magnitude less than previously reported. An acetone/water solution provided consistent recovery of catechin from soil, with percent recovery depending upon soil type. We evaluated soils from two spotted knapweed sites in Montana, USA, but found no measurable catechin. Idaho fescue, a native species reportedly sensitive to catechin, only exhibited slightly reduced growth at concentrations 10 times higher than previously reported to cause 100% mortality. Our results emphasize that more research is required to clarify the role of catechin in the invasion of spotted knapweed.     

Distribution of Insect Attacks in Biological Control of Weeds: Infestation of Centaurea virgata Flowerheads by a Gall Fly

The success of biological control efforts to reduce weed density through release of insects may depend as much on the distribution of insect attacks among individual plants or plant parts as on the mean level of infestation. We used an index of dispersion to describe the distribution of Urophora quadrifasciata (Diptera: Tephritidae) galls among squarrose knapweed (Centaurea virgata) flowerheads at 18 west central Utah sites in the first 5 years following introduction of the biological control agent. Two thirds of the samples showed a significantly aggregated distribution of galls among flowerheads. Statistical analysis showed that site and year accounted for relatively small proportions of the variance in the index of dispersion. The degree of gall aggregation among flowerheads was positively correlated with the mean flowerhead quality (mean number of seeds per flowerhead; P = 0.013) and tended to be negatively correlated with the mean fly density per flowerhead at a site in a given year (P = 0.097). Our data suggest that higher quality flowerheads, and possibly higher quality plants, are preferentially attacked by U. quadrifasciata and therefore are more heavily subject to reduced reproductive potential through biological control. However, an aggregated distribution of fly attacks may undercut the potential of the fly to reduce seed production by the weed population as a whole. Understanding both the distribution of insect attacks among individual plants and the behavioral mechanisms producing such distribution patterns is important to the biological control of weeds.     

Testing biological control agent compatibility: Cyphocleonus achates and Larinus minutus on diffuse knapweed

While weed biological control success is typically achieved with one agent, multiple agents are invariably introduced. Biological control agents that share a host–plant may interact either directly or indirectly through changes in host–plant quality. Negative interactions could reduce the impacts of the agents on the density of their host–plant while positive interactions (facilitation) could improve biological control success.In the Okanagan Valley of British Columbia, Canada, initial declines in the invasive rangeland weed, diffuse knapweed (Centaurea diffusa) were attributed to the introduction of the weevil Larinus minutus. A second weevil, Cyphocleonus achates has recently become common on diffuse knapweed. We sought to determine if the recent increase of C. achates could threaten the success of L. minutus. We considered whether L. minutus colonisation or performance remained the same when C. achates was present, and whether the two agents acted independently to reduce plant performance.Neither changes in colonisation rates nor competitive interactions were apparent between C. achates and L. minutus. Both insects reduced plant performance and, for all metrics, the reduction in plant performance by one species was independent of the second. The two agents appear to be compatible and both should contribute to the control of diffuse knapweed. To assess how biological control agents interact requires understanding both their competitive interactions and their joint effects on the shared host.     

横斑腹小鸮一新亚种—杂斑腹小鸮(鸮形目:鸱鸮科)

在横断山区鸟类考察过程中,发现采自四川宝兴县硗碛和雅江县八角楼的两号小鴞属标本与原记录的种类有显著差异,经研究认为是横斑腹小鴞(Athene brama)的一新亚种,命名为: 横斑腹小鴞 新亚种—杂斑腹小鴞Athene brama poikila Subsp.nov. 正模标本 雄性成鸟(采集号6079),1964年12月6日,采自四川省宝兴县的硗碛,海拔高度2,200米。标本保存在四川农业大学。     

Spillover of Drosophila suzukii between noncrop and crop areas: implications for pest management

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Genetic differentiation and inferred dynamics of a hybrid zone between Northern Spotted Owls (Strix occidentalis caurina) and California Spotted Owls (S. o. occidentalis) in northern California

Genetic differentiation among Spotted Owl (Strix occidentalis) subspecies has been established in prior studies. These investigations also provided evidence for introgression and hybridization among taxa but were limited by a lack of samples from geographic regions where subspecies came into close contact. We analyzed new sets of samples from Northern Spotted Owls (NSO: S. o. caurina) and California Spotted Owls (CSO: S. o. occidentalis) in northern California using mitochondrial DNA sequences (mtDNA) and 10 nuclear microsatellite loci to obtain a clearer depiction of genetic differentiation and hybridization in the region. Our analyses revealed that a NSO population close to the northern edge of the CSO range in northern California (the NSO Contact Zone population) is highly differentiated relative to other NSO populations throughout the remainder of their range. Phylogenetic analyses identified a unique lineage of mtDNA in the NSO Contact Zone, and Bayesian clustering analyses of the microsatellite data identified the Contact Zone as a third distinct population that is differentiated from CSO and NSO found in the remainder of the subspecies' range. Hybridization between NSO and CSO was readily detected in the NSO Contact Zone, with over 50% of individuals showing evidence of hybrid ancestry. Hybridization was also identified among 14% of CSO samples, which were dispersed across the subspecies' range in the Sierra Nevada Mountains. The asymmetry of hybridization suggested that the hybrid zone may be dynamic and moving. Although evidence of hybridization existed, we identified no F1 generation hybrid individuals. We instead found evidence for F2 or backcrossed individuals among our samples. The absence of F1 hybrids may indicate that (1) our 10 microsatellites were unable to distinguish hybrid types, (2) primary interactions between subspecies are occurring elsewhere on the landscape, or (3) dispersal between the subspecies' ranges is reduced relative to historical levels, potentially as a consequence of recent regional fires.