Critical Assessment of Claims Regarding Management of Feral Cats by Trap–Neuter–Return

Abstract:  Many jurisdictions have adopted programs to manage feral cats by trap–neuter–return (TNR), in which cats are trapped and sterilized, then returned to the environment to be fed and cared for by volunteer caretakers. Most conservation biologists probably do not realize the extent and growth of this practice and that the goal of some leading TNR advocates is that cats ultimately be recognized and treated as "protected wildlife." We compared the arguments put forth in support of TNR by many feral cat advocates with the scientific literature. Advocates promoting TNR often claim that feral cats harm wildlife only on islands and not on continents; fill a natural or realized niche; do not contribute to the decline of native species; and are insignificant vectors or reservoirs of disease. Advocates also frequently make claims about the effectiveness of TNR, including claims that colonies of feral cats are eventually eliminated by TNR and that managed colonies resist invasion by other cats. The scientific literature contradicts each of these claims. TNR of feral cats is primarily viewed and regulated as an animal welfare issue, but it should be seen as an environmental issue, and decisions to implement it should receive formal environmental assessment. Conservation scientists have a role to play by conducting additional research on the effects of feral cats on wildlife and by communicating sound scientific information about this problem to policy makers.     

蠕虫污泥减量效果及其影响因素分析

研究了蠕虫生长在活性污泥法中试系统的污泥减量效果及其对出水水质的影响 ,同时对蠕虫生长的影响因素进行了初步分析 .结果表明 ,除了初始的20d之外 ,整个试验过程中均有蠕虫出现 ,其中红斑瓢体虫(Aeolosomahemprichicii)和仙女虫(Naiselinguis)交替占据优势地位 ,但红斑瓢体虫占据主导地位的时间长于仙女虫 ,而吻盲虫 (Pristinaaequiseta)只是偶尔存在 .蠕虫连续保持高密度生长 (曝气池中蠕虫总密度大于 30条 /mg)长达 172d .高密度下的蠕虫生长不仅能显著降低污泥产率 ,而且能明显提高污泥的沉降性能 .蠕虫密度越高 ,出水水质越差 .仙女虫比红斑瓢体虫具有更大的污泥减量能力 ,并且前者对出水水质的影响也大于后者 .蠕虫生长不影响硝化过程 ,但当仙女虫占优势时 ,蠕虫生长会导致出水PO3₄^3--P浓度的升高 .蠕虫生长影响因素的分析表明 ,只有污泥龄对 2种蠕虫的生长没有影响 ,但温度和水力停留时间均能显著影响它们的生长 .     

Mechanical defence in seeds to avoid predation by a granivorous ant

Harvester ants have traditionally been considered as seed predators that negatively affect plants. In some cases, however, they can also act as positive seed dispersers. During field observations, we noted that a portion of Psoralea bituminosa seeds that were collected and carried to the nest by the granivorous harvester ant Messor barbarus were discarded intact in refuse piles outside the nest. We analyzed and compared the physical characteristics of size, mass and toughness in P. bituminosa seeds from two different origins: intact seeds found in the ant's refuse piles and seeds collected directly from the plants. Seeds from refuse piles were similar in width but lighter and tougher than seeds from the plant. Our results point to a mechanical defence based on seed toughness to avoid predation by M. barbarus and suggest that an elevated proportion (~69%) of the seeds produced by P. bituminosa could be too tough to be consumed by this ant. These transported but uneaten seeds could benefit by being moved far from the mother plant and this could act as a selective evolutionary pressure towards tough seeds.     

几种捕食性微小动物对铜绿微囊藻及孟氏浮游蓝丝藻生长的抑制作用

为了探索治理蓝藻水华的方法,利用大型湖泊模拟装置,研究了几种捕食性微小动物(僧帽触口虫、红眼轮虫、红斑飘体虫、多刺裸腹溞以及点滴虫等)对铜绿微囊藻及孟氏浮游蓝丝藻生长的抑制作用以及人造根对微小动物的作用.结果表明,僧帽触口虫有较强的生存能力,对孟氏浮游蓝丝藻的控制有明显作用;点滴虫对铜绿微囊藻有很强的捕食能力,可以有效控制其生长;点滴虫与僧帽触口虫的联合应用,对控制蓝藻水华有重要作用;人造根系有利于微小动物的生长,其对点滴虫的作用小于对僧帽触口虫的作用.     

鼎湖山锥栗种子特征及其对动物取食格局的影响

通过对鼎湖山自然保护区锥栗种子特征的分析及进行种子取食实验，研究探讨了锥栗种子特征对动物取食格局的影响。结果表明，锥栗作为鼎湖山季风常绿阔叶林中的重要建群种之一，其更新困难的主要原因就在于种子扩散前后面临巨大的取食压力。动物对种子取食偏爱同种子大小呈现出一定的相关性，随着种子尺寸增加，取食率有线性增加的趋势。但是，锥栗应对动物取食并非完全被动的，它也发展了一些特有的生活史策略。锥栗种子的颜色与环境凋落物及土壤色相似，可以减少被取食者发现的机率。更重要的是，锥栗种子带刺的总苞有良好的保护作用。具总苞的种子取食的强度，显著低于无总苞的种子（P〈0．01）。     

Differences in Predators of Artificial and Real Songbird Nests: Evidence of Bias in Artificial Nest Studies

Abstract:  In the past two decades, many researchers have used artificial nests to measure relative rates of nest predation. Recent comparisons show that real and artificial nests may not be depredated at the same rates, but no one has examined the mechanisms underlying these patterns. We determined differences in predator-specific predation rates of real and artificial nests. We used video cameras to monitor artificial nests baited with quail and plasticine eggs and Field Sparrow ( Spizella pusilla ) and Indigo Bunting ( Passerina cyanea ) nests in field habitats in central Missouri (U.S.A.). Although daily predation estimates (all predators pooled) were similar between artificial and real nests, predators differed substantially in their depredation of artificial versus real nests. Snakes were the major predator at real nests, and raccoons ( Procyon lotor) were the major predator at artificial nests. We found strong support for models that distinguished predation between two or among three predator groups and between artificial and real nests. There was no snake predation of artificial nests, and the odds of predation of artificial nests was 115–551% (95% confidence interval) and 2–154% of the odds of predation of real nests by mammals and birds, respectively. Artificial nests with plasticine eggs could not be used reliably to identify predators. In several cases plasticine eggs were marked by mice, and raccoons were recorded on video removing the quail egg. Because biases for artificial nests were positive for some predators and negative for other predators (and could be compensating), and potentially existed for all predator groups, conclusions based on artificial nest studies should be suspect even when there is evidence that overall predation rates are similar among real and artificial nests.     

Effect of bombardier beetle spray on a wolf spider: repellency and leg autotomy

Summary. Data are presented on the repellency of the spray of a bombardier beetle (Pheropsophus aequinoctialis) to a lycosid spider (Lycosa ceratiola). The secretion is shown to cause the spider to desist from its assault on the beetle within, on average, 58 ms of onset of the beetle’s secretory emission, a reaction time that is at a par with latencies previously reported for startle, escape, and avoidance reactions of cockroaches, flies, and moths. Spray ejections by the beetle, are shorter in duration (43 ms, on average) than the response time of the spider, an indication that the beetle does indeed pack a formidable “punch” into its ejection. After being hit by a beetle’s spray, L. ceratiola were found occasionally to autotomize one or two of their legs. It is argued, but not proven, that this unusually severe effect from exposure to an arthropodan defensive secretion may be caused by the high temperature of the bombardier beetle spray.     

Can the ratio of aromatic skeletons explain cross-species responses within evolutionarily conserved Ostariophysan alarm cues?: testing the purine-ratio hypothesis

Summary. While the response to damage-released chemical alarm cues within the superorder Ostariophysi appears to be highly conserved across species, it is generally observed that the intensity of response to heterospecific alarm cues decreases with increasing phylogenetic distance. Recent studies have demonstrated that purine-N-oxides function as chemical alarm cues within Ostariophyian fishes and that the nitrogen-oxide functional group is conserved as the chief molecular trigger. According to the purine-ratio hypothesis, these cross-species differences may be due to the relative proportion of different carrier compounds associated with the nitrogen-oxide molecular trigger. To test this hypothesis, we exposed glowlight tetras (Hemigrammus erythrozonus, Characidae, Ostariophysi) to one of five synthetic stimuli (hypoxanthine-3-N-oxide (H3NO), pyridine-N-oxide (PNO) or mixed stimuli of 75 % H3NO-25 % PNO, 50 % H3NO-50 % PNO, or 25 % H3NO-75 % PNO), natural conspecific chemical alarm cue or a distilled water control. We quantified changes in shoal cohesion and vertical area use as species typical indicators of an antipredator response. As predicted, response intensity decreased as the ratio of hypoxanthine-3-N-oxide to pyridine-N-oxide decreased and the strongest response was to natural alarm cue. These results suggest that species-specific carrier compounds may account for the well-documented cross-species differences in the response to heterospecific alarm cues within phylogenetically related taxa.