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91.
In general, reproductive output in long-lived bird species increases in older compared to younger individuals. Therefore, experienced mates should be advantageous for first-time breeders. To examine requirements and consequences of experienced pair mates we investigated the first pair bonds of common terns, Sterna hirundo, recruiting to their natal colony. We found that male recruits were usually the same age as their mates, whereas female recruits were usually the younger member of the pair. In order to acquire experienced mates, it was necessary for males to arrive early in the year of recruitment. Mates with 2 or more years of breeding experience were only attainable by male recruits characterised by greater body mass and age. Female recruits arrived more than 1 week later than their experienced mates and significantly later in the season than male recruits paired with experienced females. In general, females first bred at a younger age than males, and neither the female recruits body mass nor their age was related to the level of experience of their first mate. These sex-specific differences in obtaining an experienced mate did not result in different levels of reproductive success between the sexes. Male and female recruits with mates with 2 or more years breeding experience benefited from having experienced mates: they had greater reproductive success. First-time breeders paired with mates with only 1 year of breeding experience did not differ from pairs where both members were breeding for the first time in terms of reproductive success, but clutches were larger. Our results illustrate not only different prerequisites for males and females, but also males need for experienced mates. Delayed male breeding (postponing breeding for another year), supposed to be a negative trait, and high body mass, supposed to be a trait of superior individual quality, can be combined in some individuals, improving reproductive success and showing that breeding common terns use a range of tactics to begin reproduction.Communicated by F. Trillmich  相似文献   
92.
In many bird species, the female alone incubates the eggs, but the male provides her with some food during the incubation period. In cooperatively breeding species, helpers might be expected to assist the breeding male in provisioning the female, but their contribution has been generally ignored. Here, I show that in the green woodhoopoe, Phoeniculus purpureus, the breeding male and helpers of both sexes bring food to the incubating female. The helpers did not increase the overall amount of provisioning the female received: groups of all sizes delivered a similar amount of food per hour. Helpers did, however, reduce the workload of the breeding male. Male and female helpers provisioned incubating females equally, as expected in a species where both sexes are likely to derive equal benefits from their helping behaviours. Female nest attendance was positively related to the level of group provisioning, but only in the short term. Thus, the female-nutrition hypothesis, which suggests that incubation feeding can provide an important source of energy to the breeding female, is supported in the green woodhoopoe.Communicated by I. Hartley  相似文献   
93.
畜禽养殖场排放物病原微生物危险性调查   总被引:5,自引:0,他引:5  
以粪大肠菌群和沙门菌为指标,采集江苏省内10家不同养殖类型畜禽养殖场的排放物及其周边水、土样共37个进行观察与计数,同时分析排放污水中大肠杆菌的耐药性以及禽畜排泄物对土壤和水体耐药细菌数的影响.结果表明:调查的10家养殖场中有9家粪便未经无害化处理直接排放到水体或施于农田,且排放物的粪大肠菌群数全部严重超标,沙门菌检出率达19%,施新鲜粪肥的土壤中粪大肠菌群数(MPN,最大可能数)在105 g-1以上,水体中分离出的大肠杆菌表现出多重耐药性,抗生素抗性细菌总数也远高于未施新鲜粪肥的土壤及水体.  相似文献   
94.
In this study we examined parentage within broods of the cooperatively breeding noisy miner using multi-locus DNA profiling. Previous studies of noisy miners described them as highly promiscuous, leading to the suggestion that promiscuous mating behaviour was a tactic used by females to recruit males as provisioners to their nests (Dow 1978). At our study site in south-east Queensland, Australia, we found that both multiple and extra-group paternity (i.e. a female mating with a male outside the group of male provisioners at her nest) were rare. In nests where multiple paternity was possible (i.e. clutch size > 1) 97% of 31 broods were sired by only a single male. Overall, 96.5% of all nestlings (n = 85) were the result of monogamous matings. Also, at the vast majority of nests, the male that sired the nestlings was also the main provisioner among all male nest attendants. Our results show that the mating system of the noisy miner can no longer be considered cooperative polyandry (Brown 1987) but is clearly genetic monogamy. We discuss the implications of this finding for understanding the complex social system of this species.  相似文献   
95.
Abstract:  In contemporary fragmented landscapes, edges are commonplace, and understanding the effects of edge environments is thus essential for the conservation of forest communities. The reproductive output of forest passerines is often reduced close to forest edges. Possible explanations include overcrowding by conspecifics, elevated rates of predation, and the occurrence of lower-quality habitat and/or individuals at forest edges. We attempted to separate these processes by examining edge effects in the absence of nest predation and by effectively controlling for differences in breeding density and the quality of habitats and individuals. We used an edge distance index (EDI), which accounts for the number and distribution of edges in close proximity to a breeding location, to help explain variation in breeding density, nesting success, and reproductive traits of 8308 pairs of Great Tits ( Parus major ) breeding between 1965 and 2005, in Wytham, near Oxford, United Kingdom. Results from linear mixed modeling confirmed higher breeding density and a higher proportion of immigrant individuals at forest edges. Nevertheless, independently of these effects, we also found that birds laying later, with smaller clutches but larger eggs, were typical of edge environments. The number of offspring recruited to the breeding offspring per breeding attempt was also reduced at edges, both directly and mediated through changes in clutch size and laying date. Edge effects on life histories were detectable within individual females and up to 500 m from the woodland edge. Woodland edges are increasingly common in contemporary fragmented landscapes. Therefore these results, which suggest a pervasive effect of edges on reproduction, are of considerable importance to the management and conservation of forest communities.  相似文献   
96.
本文介绍了地震动物试验场建立、动物观测、数据处理和饲养管理等方面的工作,为动物习性异常与地震关系的研究积累了可贵的观测资料,对于动物的行为异常预报地震具有一定的参考价值。  相似文献   
97.
闽东南特色农业生态模式研究   总被引:12,自引:3,他引:12  
基于闽东南的资源优势,把发展亚热带水果作为特色农业。由于生态环境脆弱,必须寻求特色农业生产的最佳模式。本研究设计果农草牧复合系统作为特色农业的生态模式。试验表明:生态模式与传统模式相比,泥沙流失量仅是传统模式的26.3%和48.4%,0~20cm土层的有机质含量增加3.8g/kg和5.5g/kg。土地单位面积能量总产出是传统模式的5.1倍。本生态模式显示生产良好循环,取得有效的生态和经济效益,并有很好的发展前景。  相似文献   
98.
畜禽养殖废弃物及农业氮磷流失造成的环境面源污染已经成为太湖流域湖泊和水体污染的主要来源之一.通过现场勘查、文献查阅、实地调研等方法,对以太仓为代表的江苏太湖流域畜禽养殖及农业氮磷流失造成的农村生态环境污染问题进行了分析,研究提出了污染防治示范区构建的指导思想、基本原则、技术路径、技术及模式创新点,用五大发展新理念指导污染防治示范区构建,创新畜禽养殖废弃物及农业氮磷污染防治的产业化模式、区域分散畜禽粪便收集服务的社会化体系、覆盖农业氮磷污染防治全程的可控化技术体系.  相似文献   
99.
Global amphibian declines are one of the biggest challenges currently facing the conservation community, and captive breeding is one way to address this crisis. Using information from the International Species Information System zoo network, we examined trends in global zoo amphibian holdings across species, zoo region, and species geographical region of origin from 1994 to 2014. These trends were compared before and after the 2004 Global Amphibian Assessment to assess whether any changes occurred and whether zoo amphibian conservation effort had increased. The numbers of globally threatened species (GTS) and their proportional representation in global zoo holdings increased and this rate of increase was significantly greater after 2004. North American, European, and Oceanian GTS were best represented in zoos globally, and proportions of Oceanian GTS held increased the most since 2004. South American and Asian GTS had the lowest proportional representation in zoos. At a regional zoo level, European zoos held the lowest proportions of GTS, and this proportion did not increase after 2004. Since 1994, the number of species held in viable populations has increased, and these species are distributed among more institutions. However, as of 2014, zoos held 6.2% of globally threatened amphibians, a much smaller figure than for other vertebrate groups and one that falls considerably short of the number of species for which ex situ management may be desirable. Although the increased effort zoos have put into amphibian conservation over the past 20 years is encouraging, more focus is needed on ex situ conservation priority species. This includes building expertise and capacity in countries that hold them and tracking existing conservation efforts if the evidence‐based approach to amphibian conservation planning at a global level is to be further developed.  相似文献   
100.
Abstract:  Stochastic variation of sex ratio has long been appreciated as a potential factor driving small populations to extinction, but it is not the only source of sex-ratio bias in small populations. We examined whether some consequences of sex allocation could affect extinction risk in small populations of size-dimorphic birds such as eagles. We report variations in sex ratio at fledging from a long-term study of a declining population of Spanish Imperial Eagles ( Aquila adalberti ). Nestling sex-ratio deviation apparently was mediated by age of breeders, whereas territory quality had no obvious effect. Adult–adult pairs produced the same proportion of both sexes in high- or low-density situations, but pairs with at least one member in nonadult plumage class produced more males. As the population declined over a period of years, the proportion of breeders with immature plumage increased; consequently, the proportion of fledgling males increased. However, when population density was high, the proportion of breeders with immature plumage decreased and more female offspring were produced. This relationship between population density, composition of breeder age, and fledgling sex ratios allowed us to make predictions of extinction risk due to nonstochastic deviations of sex ratio in small, declining populations. In the study population, on the basis of the Vortex simulation results, an estimated reduction of 42.5% in predicted mean time to extinction was attributed solely to biased sex ratio.  相似文献   
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