长江江豚对人工投食适应过程的观察

作者于1989,1992,2001 和2003 年,从长江铜陵江段共捕获24 头长江江豚,在长江干流水域中,用不同的围养方式做摄食行为的观察,累计88 d。结果表明,野外捕获的长江江豚对人工投喂有3 种适应行为:(1)拒食行为;(2)警戒行为;(3)摄食行为。长江江豚的平均拒食天数为2.4 d,其中成年江豚拒食达3 d,而未成年江豚仅拒食1.5 d,两者差异极为显著(P < 0.01)。在冬季和春季圈养试验中,长江江豚的日食量随时间呈上升趋势,冬春季差异显著(P <0.01)。第2 周后江豚警戒行为所用时间不足3 min,但持续时间较长。根据冬季观察,7 周后长江江豚在40 min 内所摄取的食量不足体重的7% ,推测其摄食行为仍处在适应调整阶段。     

半自然水域中长江江豚春季昼间活动节律的观察

2004年2~4月,采用岸边定点和流动观察的方法对生活在半自然夹江水域中的5头长江江豚(Neophocaena phocaenoides asiaeorientalis)昼间活动节律进行了初步研究。结果表明,成年长江江豚春季昼间行为表现为摄食所占比例最多,为62.5%;其次是玩耍、移动和休息,分别为16.4%、10.7%和8.6%;其他行为最少,为1.8%。摄食高峰在8:30~16:30时,玩耍和移动也主要发生在该时段,休息存在1个高峰期。主要原因是人工投喂和在春季中午前后鱼群活动剧烈,长江江豚主要活动是摄食行为,而休息行为多发生在早晨和傍晚。     

长江中下游江豚种群现状评价

作者根据近年在长江中下游对江豚进行考察的资料和收集到的标本,系统分析评价了长江中下游江豚的种群现状,主要结果如下:1.长江江豚上至宜昌(距河口1669公里),下至长江口,以及洞庭湖、鄱阳湖均有分布。分布型式是沿长江纵向呈集群性分布,横向呈趋岸性分布;2.长江中下游江豚种群数量估计为2700头。其数量冬季最高,夏季最低。夏季的SPUE值仅为冬季的48.7％—58.6％;3.长江中下游江豚群体以1—5头最为常见,占88％;4.理论推算长江中下游每年新产生个体为539头,年出生率为20％;5.通过分析比较长江中下游和中国沿海以及日本Inland Sea江豚种群数量变动趋势,推测长江中下游江豚很可能进行“江—海”、“海—江”长距离大规模的迁移,这种迁移与生殖有关。     

铜陵淡水豚国家级自然保护区半自然水域鱼类群落结构研究

2021年5月采用多网目复合刺网和抛网相结合的方法,对铜陵淡水豚国家级自然保护区半自然水域夹江鱼类群落进行了调查。共采集到鱼类30种,隶属于5目7科27属。相对重要性指数显示鲢（Hypophthalmichthys molitrix）、贝氏?（Hemiculter bleekeri）、似鳊（Pseudobrama simoni）、团头鲂（Megalobrama amblycephala）、鳊（Parabramis pekinensis）和翘嘴鲌（Culter alburnus）为群落优势种。与长江江豚（Neophocaena asiaeorientalis）争夺饵料资源的凶猛性鱼类比例达到2.4%,体长分布显示夹江中存在大量长江江豚无法摄食的大个体鱼类（17.5%）。夹江鱼类群落的Shannon-Weiner指数、Simpson指数、Margalef指数和Pielou均匀度指数依次分别为1.955~2.181,0.794~0.820,2.952~3.856和0.705~0.730。空间生态位宽度指数、平均拥挤度和生态位重叠指数表明,夹江优势种鱼类可能存在较为激烈的种间竞争。建议清理鳡（Elopichthys bambusa）、翘嘴鲌、达氏鲌（Culter dabryi）和乌鳢（Channa argus）等凶猛性鱼类及其他与长江江豚争夺饵料的鱼类,及时捕捞全长超过25 cm的鱼类,补充投放鲢、似鳊、银鲴（Xenocypris argentea）等长江江豚偏好摄食鱼类。     

白鱀豚饲养的研究

饲养池水使用自来水是切实可行的。水温在冬季不低于4℃,夏季不超过33℃。白暨豚以淡水鱼类为食,其日食量一般占体重的10—11%,炎夏减到8—9%,寒冬可增到12%。豢养四年的淇淇,其体长和体重增长的关系式为:y=-237.4 2.2x。饲养的关键有二:一是水质,经常洗池换水以保持水质清洁;二是食物,饲料鱼要挑选健康、新鲜,无污染的鱼类,喂前进行消毒,每天还要给以维生素类药品,以作营养补充。     

保护需要科技支撑 人工繁殖

<正>2005年7月5日.人工饲养条件下第一头江豚在武汉白鱀豚馆繁殖成功。除了就地保护和迁地保护之外,建立一定规模的饲养群体并开展人工繁殖研究是保护长江江豚这一濒危物种的另外一种重要保护策略。自1996年开始.中国科学院水生生物研究所白鱀豚馆先后从长江石首、嘉鱼和城陵矶江段引入3头江豚(2雌1雄)并取得     

长江天鹅洲故道江豚的集群规模及其时空分布

2 0 0 1年 5月至 2 0 0 2年 4月 ,选择使用岸上定点观察、流动观察和水上流动观察 3种观察方式 ,对长江天鹅洲故道内约 2 0头江豚的集群状况进行了一个周年的监测 ,共观察到江豚集群 5 88次。结果表明 :天鹅洲故道内江豚以集群的方式迁移和活动 ,集群规模从 2— 2 0头不等 ,一般分成 2个 9— 11头规模的亚群体 ,2个亚群体活动范围相对独立 ,其活动主要为D区和H区。每个亚群体又常分成规模较小的核心群体 ,其中 3头集群最多。一年中春、秋和冬季江豚集群状况基本相同 ,而夏季有所差别。天鹅洲故道江豚集群在白天期间有 3个高峰期 ,主要发生在9:0 0— 11:30 ;12 :30— 16 :15和 17:15— 18:0 0 ;正午时间 ,江豚的集群活动处于相对低谷。江豚集群相对集中在天鹅洲故道D、E、F、G和H区域 ,占 70 % ,江豚在上下区域集群相对较少。根据江豚集群规模在天鹅洲故道的时空分布规律 ,作者对长江天鹅洲保护区江豚群体的保护与管理提出了科学的合理化建议。     

野生与豢养长江江豚血清氨基酸含量比较

应用高效液相色谱(HPLC)技术,首次测定了湖北石首长江天鹅州白豚自然保护区野生长江江豚(Neophocaena phocaenoides asiaeorientalis)和中国科学院水生生物研究所白豚馆人工饲养的长江江豚血清中17种氨基酸的含量.结果表明,除了脯氨酸Pro、蛋氨酸Met和组氨酸His外,人工饲养江豚血清中其余14种氨基酸(天门冬氨酸Asp、谷氨酸Glu、丝氨酸Ser、精氨酸Arg、甘氨酸Gly、苏氨酸Thr、丙氨酸Ala、异亮氨酸Ile、亮氨酸Leu、苯丙氨酸Phe、缬氨酸Val、赖氨酸Lys、酪氨酸Tyr、胱氨酸Cys)的含量显著高于野生长江江豚血清中相应氨基酸的含量.野生江豚和人工饲养江豚的血清氨基酸含量均没有显著的性别差异.野生江豚性成熟个体与未成熟个体之间血清氨基酸含量也没有显著性的差异.在所检测的17种氨基酸中,豢养江豚Glu含量最高,其次为Asp和Lys.野生江豚同样是Glu最高,其次是Lys和Asp.豢养和野生江豚都是Met含量最低.野生和豢养江豚必需氨基酸(EAA)和非必需氨基酸(NEAA)之间的比率分别是0.83和0.92,具有极显著的差异(p <0.01).     

湖口至南京段长江江豚种群现状评估

对湖口至南京段长江江豚的考察资料进行分析。结果表明：1、研究长江江豚不同的生态行为,能提高野外计数的准确性;2、长江江豚大规模集群（10头以上）发生在特定的江段,近年来出现的机率在下降;3、湖口至南京段长江江豚数量为1054头,其中小孤山至湖口段种群密度最高;4、湖口至南京段支流中分布的长江江豚约占该江段种群数量的9.3%。     

鄱阳湖及其支流长江江豚种群数量及分布

在1997 年11 月至1998 年11 月的134 d 中, 大致按一年四季, 分4 次对鄱阳湖及其主要支流中的长江江豚种群数量、数量的季节变动、分布、行为、江豚栖息地环境、人类活动对江豚的影响进行了考察。江豚的分布主要集中在鄱阳湖湖区, 赣江、信江、抚河等主要支流的中下游和支流入湖的湖口附近。冬、春、秋3 个季节鄱阳湖水系长江江豚种群数量的估计值分别为91 头、431 头和260头。即, 鄱阳湖江豚的种群数量约为100～400 头,其种群数量随季节、水位、鱼类资源的变化而呈现出相应的变化。     

北京十渡自然保护区越冬黑鹳的种群生态调查

为了解黑鹳在北京地区越冬的生态特点,于2004年1月至2007年3月采用直接观察法对北京市拒马河自然保护区越冬黑鹳的数量、栖息地选择和取食规律进行了观察。结果表明拒马河流域已成为北京地区越冬黑鹳稳定的栖息地,种群数量超过20只。越冬聚群从11月开始,分群时间为次年2月。取食地相对集中,取食活动在越冬初期以上午和中午为主,中期以下午为主,末期则分为早晚两个时段。干旱和人为活动导致的适宜取食地减少是影响黑鹳生存的主要因素。     

Size‐specific effects of bighead carp predation across the zooplankton size spectra

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Comparative studies on the feeding selectivity of silver carp Hypophthalmichthys molitrix and bighead carp Aristichthys nobilis

Silver carp and bighead carp exhibited size-selection for food particles in aquarium experiments, but did not select their preferred species of plankton actively when they were distributed evenly in the water. They also possessed the capacity of selection for feeding area. The removal rates (% g⁻¹ fish weight) of silver carp for smaller plankton (phytoplankton) were higher than those of bighead carp. The removal rates by the latter for bigger plankton (zooplankton) were higher than those of silver carp, but for plankton about 70 μm dia. the rates by the two species were almost equal.     

Variations in independent areas of activity of captive Yangtze finless porpoises, <Emphasis Type="Italic">Neophocaena phocaenoides asiaeorientalis</Emphasis>, during the acclimation period after wild capture

The acclimation process of Yangtze finless porpoises to a limited holding pool after their introduction to this new captive environment is presented. One male (#1) and two female (#2, #3) finless porpoises, newly captured from two different sections of China’s Yangtze River, were observed in an indoor holding pool with an area of 155 m² from January 1997 to January 1998 (animal #3 was removed from the pool in mid-February 1997). Three separate areas in the pool were predefined. Time spent in each of the areas was individually monitored two or three sessions a week using the focal sampling method. In total, 71.3 h of observations (316 sessions) were recorded, with an average observation time each month of about 2.4 h (10 sessions) for each porpoise. The percentage of time spent in each area per month was calculated for each porpoise, and the variations in the percentage of time spent in each area was compared. Results indicated that independent areas of activity existed among porpoises during the early stages of captivity. However, over time, the frequent approaches of the female to the male caused these areas to fade away, resulting in almost equal use of the entire pool area by the newly formed group. The existence of the independent areas of activity during the early months of captivity indicates that newly introduced individuals from different wild subgroups may need separate areas for activities. However, further studies with more animals are needed to draw more general conclusions about the individual areas of activity of this subspecies when in captivity.     

Effects of feeding time constraints on body mass regulation and energy expenditure in wintering dunlin (Calidris alpina)

We examined the effects of time-restricted feeding on regulationof body mass and activity energy expenditure in captive winteringdunlin (Calidris alpina) held in outdoor aviaries at TomalesBay, California. In the first of two experiments, we comparedbirds under 24 h : 24 h (fasting : ad libitum feeding) foodrestriction with controls under continuous ad libitum feeding. In the second experiment, we compared birds under 24 h : 6 h: 12 h : 6 h (fasting : ad libitum : fasting : ad libitum)food restriction with birds under 24 h : 24 h food restriction.We estimated total energy expended on activities from dailymass balance using an additive model based on measures of grossenergy intake, thermoregulation, basal metabolism, and a sensitivity analysis of gross utilization efficiency and energy densityof reserve body tissue. Dunlin under 24 h : 24 h food restrictionovercompensated for body mass lost while fasting, increasingtheir body mass relative to controls fed ad libitum. Dunlinunder 24 h : 6 h : 12 h : 6 h food restriction were unable to recover body mass lost during the first fasting day. Whenallowed to feed, food-restricted birds reduced the amount ofenergy spent on being active and increased food intake andenergy storage relative to controls, but when forced to fast,they increased their activity energy expenditure. These patterns suggest winter body mass regulation consistent with the behaviorsof free-living dunlin in winter.     

Vulnerability to severe weather and regulation of body mass of Icelandic and British Redshank Tringa totanus

During severe weather, Redshanks suffer the heaviest mortality amongst all the shorebird species wintering around the North Sea coasts of the British Isles. An earlier study had suggested that this resulted from a failure to accumulate sufficient body fat reserves before mid-winter. Detailed field studies in northeast England between 1993 and 1995 of seasonal changes in body mass, and in estimated lean and fat masses, of two races of Redshank, both of which winter in the same estuary, were accompanied by similar studies of small numbers held in captivity with unlimited food. After differences in body size were allowed for, there were no differences in body composition and its seasonal pattern of change in birds of the Icelandic and British races. Body mass changes in wild birds paralleled those in captives between November and March, and mid-winter levels were not limited by food supply; indeed they were slightly higher in a winter with lower prey densities. It is concluded that Redshanks regulate body mass and, indirectly, fat reserves at levels set by a trade-off between the risks of predation and starvation. Unlike most other shorebird species, they take very small prey in relation to their body size and hence must feed for long periods during each tidal cycle to achieve their daily energy intake needs. Thus they have little scope to extend their feeding time during severe weather, which also forces them to feed on ice-free exposed coastal habitats where wind chill cannot be avoided. Both factors lead to more rapid depletion of fat reserves than in other species which have higher energy intake rates or lower total daily requirements.     

By-catch and drowning in harbour porpoises (<Emphasis Type="Italic">Phocoena phocoena</Emphasis>) stranded on the northern Dutch coast

Stranding data and recorded post-mortem findings were studied for 153 harbour porpoises (Phocoena phocoena), which were collected by the Seal Rehabilitation and Research Centre (SRRC; Pieterburen, The Netherlands) in the period 1984–2006. Special consideration was given to ‘by-catch’ listed as a major cause of death. A distinct increase in the numbers of strandings of porpoises along the Dutch coastline has occurred in the recent years of the studied period. This corresponds to the number of porpoises observed in Dutch waters in the same period. Although strandings occurred throughout the entire year, they were most frequent during the January to July period. By-catch and drowning were noted most frequent in the winter and spring seasons (December–April). By-catch and drowned porpoises were found along the entire Dutch coastline. The numbers of animals per area varied depending on the collection efforts. At post-mortem investigation, three probable causes of death were identified most frequently: pneumonia, emaciation and by-catch/drowning. The by-catch and drowning rate was calculated to vary between 7% and 19%. Overall, the percentages obtained from this study appeared to be in line with those established by others in neighbouring countries. Varying fishing techniques are used in Dutch waters. A careful study of the fishing methods involved and close co-operation with fishermen are required to determine effective measures to reduce the by-catch of porpoises.     

Mate Choice and Hybridization in Lake Malawi Cichlids, Sciaenochromis fryeri and Cynotilapia afra

Lake Malawi is home to hundreds of cichlid species, most of which are endemic to the lake. Several of these species exhibit a remarkably similar behavioural repertoire including territorial and reproductive behaviours. Despite their diverse anatomy and body colouration, hybridization among Malawi cichlids has been observed in captivity and has also been reported to occur in nature. Here, possible factors underlying hybridization between two species, Sciaenochromis fryeri, a large piscivore, and Cynotilapia afra (Jalo reef), a small planktivore biocover grazer, were investigated in captivity. In a series of experiments the size of the territory, the size of the males and the availability of conspecific mates were manipulated. It was found that mate selection in these two species under semi‐natural conditions is dependent not only upon species‐specific cues but also upon the status of the male. Larger male body size and larger territory size was generally preferred by females and when these attributes characterized a heterospecific male they also increased the probability of heterospecific courtship. Given that spawning between the above‐mentioned species resulted in fertile offspring and that their geographical location and habitat overlap in nature, the effect of their mate‐choice strategies on hybridization and speciation is considered.     

Effect of oral diazepam on feeding behavior and activity of Hawai’i ’amakihi (Hemignathus virens)

Feeding behavior and activity during captivity were studied in wild-caught Hawai’i ’amakihi, Hemignathus virens, to evaluate diazepam's hyperphagic and anxiolytic effects. Birds were captured in mist nets, given either oral diazepam (1 mg/kg) or an equivalent volume per weight of lactated Ringer's solution orally, and held in captivity for 6 h. Thirteen-minute focal animal samples were videotaped at the beginning of each hour. Feeding behaviors, grooming and picking events, changes in position, and body weights were recorded. Mean duration of feeding, percentage of time spent feeding, and number of feeding events were significantly higher for treatment birds than for controls, and significantly increased over time. Feeding duration was significantly correlated to weight change. Weight change was not significantly different between groups, but on average treatment birds lost less weight than control birds. No significant differences in grooming behaviors were found between the groups, but there was a session effect of increased grooming over time in both groups. Also, a significant session effect in movement events was apparent, with control birds becoming less active and treatment birds becoming more active over time. Results indicate diazepam increased feeding behaviors and movement in this passerine species during a short period of captivity.