Arterial blood pressure during voluntary diving in the tufted duck,Aythya fuligula

Arterial blood pressure was monitored in voluntarily diving tufted ducks. Mean arterial blood pressure while diving increased during the pre-dive tachycardia, fell to resting levels on submersion, then gradually increased before peaking on surfacing. Estimated total peripheral resistance fell during the pre-dive and post-dive tachycardia, presumably to allow the oxygen stores to be loaded and replenished respectively and/or for carbon dioxide levels to be reduced. Changes in mean arterial blood pressure and total peripheral resistance suggest that peripheral vasoconstriction occurs in some vascular beds during a dive. An increase in arterial blood pressure (and therefore perfusion pressure) may be employed to increase blood flow and oxygen delivery to the active leg muscles.Abbreviations ecg Electrocardiogram, f _H, heart rate - MABP mean arterial blood pressure - P _b blood pressure(s) - TPR total peripheral resistance - V _b cardiac output     

西伯利亚鲟卵黄脂磷蛋白的分离纯化及性质

卵黄是鱼类胚胎发生期的主要营养物质,卵黄的含量和质量对于早期幼体维持生命和生长发育至关重要.本研究采用Sephacryl S-300凝胶过滤层析法和蛋白质电泳技术分离纯化西伯利亚鲟(Acipenser baerii)卵黄脂磷蛋白(lipovitellin,Lv),层析洗脱共得到7个蛋白峰.对每个峰进行SDS-PAGE电泳及油红O、甲基绿和Schiff试剂特异染色,峰b蛋白均呈阳性,表明峰b蛋白为西伯利亚鲟卵中的一种卵黄脂磷蛋白,SDS-PAGE电泳分析表明,其由3个亚基构成,相对分子质量分别为30.6 ku、40.8 ku和76.7 ku.对西伯利亚鲟Lv氨基酸组成进行分析,证明是一种含有相对较多天冬氨酸、赖氨酸、谷氨酸、丝氨酸、缬氨酸和亮氨酸的蛋白,并且所含鲜味氨基酸含量比其他鱼偏高.     

Abundance and feeding of wintering and migrating aquatic birds in two sampling areas of Lake Balaton in 1983–1985

The investigation was carried out at two sampling areas in Lake Balaton (surface area 600 km²), of which one was hypertrophic and the other was mesotrophic. Species diversity was higher in the hypertrophic area, primarily due to a higher number of Anatid species. Contents of crops, gizzards, and intestines were analysed in 321 of the 361 birds collected. Diet was similar in certain species (Aythya fuligula, A. f. ferina, Anas querquedula) despite differences in the trophic state of their habitats. However, in other species (Anas p. platyrhyncha, Aythya nyroca, Bucephala c. clangula), percentage distribution of food items more or less reflected the food resources of the two areas in the digestive tracts. I concluded that the former species are highly selective in their feeding.     

Use of saltwater and freshwater habitats by wintering redheads in southern Texas

Behavioral data were gathered for redheads (Aythya americana Eyton) using saltwater and freshwater habitats in southern Texas, the northern portion of their major wintering range, in 1989–90. Saltwater and freshwater habitats were used for different purposes by wintering redheads. Approximately 41% of all redheads in saltwater habitats were feeding, while only 0.1% of redheads in freshwater habitats were feeding. Redheads in saltwater habitats drank infrequently (0.3%), but 7.5% of redheads in freshwater wetlands were drinking. Only 23 courting activities were observed, but all occurred in freshwater wetlands. This study showed that redheads depend on saltwater habitats for feeding, which confirmed similar results from recent studies of redheads in the central and southern portions of the Laguna Madre in southern Texas. This study also showed that redheads depend on freshwater wetlands as sources of drinking water. This concurred with data on redhead behavior in the central portion of the Laguna Madre in Texas, but not for redheads wintering in the southern part of the Laguna Madre. Both habitats, saltwater and freshwater, must be considered as integral components of the redhead winter range throughout southern Texas.     

Effects of weather and tides on feeding and flock positions of wintering redheads in the Chandeleur Sound,Louisiana

We studied the effects of weather and tides on percent feeding and flock positions of wintering redheads (Aythya americana Eyton) in the Chandeleur Sound, Louisiana, USA. Flock scans (n = 750) were made on 55 flocks from November through March of 1988–1989. The percent of the flock that was feeding was negatively correlated with time of day, temperature, water level, and distance of the flock from shore, and was positively correlated with wind velocity, flock size, fetch, and wave height; birds also fed more in early winter and during northerly winds. Flocks were closer to land earlier in the winter on cloudy, rainy, and windy days when waves were high, and those flocks were smaller than flocks farther from shore. Conditions associated with reduced fetch by flocks included later time of day, smaller waves, warmer air temperatures, northerly wind shifts, stronger winds, increasing cloud cover, and rain. Redheads minimized energy expenditure by foraging during low tides and in shallow water closer to shore; they increased feeding and reduced fetch during times of high thermoregulatory demands.     

A Demographic model for ring-necked ducks breeding in Minnesota

Population models can provide insights into how perturbations of demographic vital rates influence population growth rates (λ) and help prioritize efforts to achieve management goals. Although population models have been developed for numerous duck species, this tool has not been developed for ring-necked ducks (Aythya collaris). Ring-necked ducks are a late-nesting species that may not be surveyed well by the May Waterfowl Survey, which is timed optimally for earlier nesting ducks like the mallard (Anas platyrhynchos). Information specific to ring-necked ducks would help identify important influences on the rate of population growth and the direction of population change. We used data from our own research during 2008–2012, long-term (1975–2016) survey data from northcentral Minnesota, USA, vital rate estimates from the literature, and long-term (1987–2016) banding data to develop a population model for ring-necked ducks. We estimated annual survival and recovery rates of after-hatching-year and hatching-year female ring-necked ducks in Minnesota. Survey results and our matrix models indicated that ring-necked ducks are declining in the forested portion of Minnesota. Thus, we examined a boom-or-bust simulation scenario that might maintain a population through periodic occurrence of exceptional reproductive years in conjunction with high hatching-year survival. Our results indicated that long-term persistence is only expected in this population if reproductive output doubled at the same time that hatching-year survival was at its highest value, or if the population is maintained through immigration. Sensitivity analysis indicated that unit changes in 30-day brood survival will produce the most change in λ in the parameter space observed, although elasticity analysis indicated that proportional changes in annual survival of adult females will produce the largest proportional changes in λ. Management to improve brood survival to increase λ might include improving the habitat quality of brood-rearing lakes, especially those with more open water and less nesting habitat than those used for nesting. Our findings might also help explain disparities between annual breeding waterfowl surveys, which indicate stable or increasing populations, and hunter experiences in the fall. In Minnesota, hunter experiences have not matched expectations based on historical fall numbers and this could occur if regional production declined and fewer young birds were available for harvest. Our findings highlight the need for further study to inform management in this rapidly changing region. © 2019 The Wildlife Society.     

三种鲟科鱼类和两种鲑科鱼类卵黄免疫球蛋白性质的比较

从施氏鲟(Acipenser schrencki)、小体鲟(Acipenser ruthenus)、西伯利亚鲟(Acipenser baeri)、哲罗鲑(Hucho taimen)和金鳟(Oncorhynchus mykiss)五种鱼类卵黄中分离、纯化Ig,并对其分子结构进行了初步研究。结果表明:五种鱼类卵中Ig的分子量分别为施氏鲟524kD、小体鲟468kD、西伯利亚鲟475kD、哲罗鲑为490kD,金鳟498kD,其Ig重链的相对分子量相同,约为97kD。轻链的相对分子量各不相同,施氏鲟为27kD,小体鲟28.5kD,西伯利亚鲟30kD,哲罗鲑28.5kD和金鳟16kD。其中西伯利亚鲟、施氏鲟和小体鲟Ig等电点约为5.85,哲罗鲑和金鳟的Ig等电点约为6.55,其蛋白质结构上具有一定的相似性,且均为糖蛋白     

Moulting diving ducks and their food supply

Numbers of moulting diving ducks at Myvatn, north Iceland, were monitored over a period of 25 years; aquatic insects (Chironomidae and Simuliidae), a major food resource, were monitored with window traps for 23 years. The response of the duck populations to changes in the food situation during the moulting period varied between species. Histrionicus histrionicus and Melanitta nigra invariably go to the sea to moult. Three species (Aythya fuligula, Clangula hyemalis and Mergus serrator) have shown long term variation in moult migration habits. Aythya marila and Bucephala islandica stay for moulting, their numbers supplemented by birds from elsewhere. A. marila is a generalist feeder and therefore at low risk of starving, the strategy of Bucephala islandica is to move within the water system where the food situation tends to alternate between the lake and the river. Numbers of Bucephala islandica males moulting on Lake Myvatn were strongly and positively correlated with chironomid numbers and those moulting on the river Laxá with Simulium vittatum, the main food resource there. We did not find convincing evidence that numbers of moulting A. marila and C. hyemalis responded to variation in the food supply during the study period. This applied also to A. fuligula in the South Basin of Myvatn, but numbers in the North Basin were positively associated with chironomid numbers. M. serrator moulting on Myvatn showed negative correlations with the chironomids, perhaps reflecting a negative association between chironomids and its main food, Gasterosteus aculeatus. Apart from safety considerations for a flightless bird, the choice of a moulting site is apparently influenced by the local food conditions on one hand and by the opportunities and risks involved in migrating to distant moulting sites with an unknown food situation on the other hand.     

Ovarian follicle dynamics of female Greater Scaup during egg production

ABSTRACT.   Studies of female waterfowl nutrient reserve use during egg production require a precise understanding of ovarian follicle dynamics to correctly interpret breeding status, and, therefore, derive proper inference. Concerns over numerical declines of North American scaup have increased the need to better understand the role of female condition in reproductive performance. We quantified ovarian follicle dynamics of female Greater Scaup ( Aythya marila ) breeding on the Yukon–Kuskokwim Delta, Alaska, using a method that accounts for within day variation in follicle size. We considered several models for describing changes in follicle growth with the best supported model estimating the duration of rapid follicle growth (RFG) to be 5.20 ± 0.52 days (±95% confidence intervals) for each developing follicle. Average diameter and dry mass of preovulatory follicles were estimated to be 9.36 mm and 0.26 g, respectively, at the onset of RFG, and these follicle characteristics were 41.47 mm and 15.57 g, respectively, at ovulation. The average diameter of postovulatory follicles immediately following ovulation was estimated to be 17.35 mm, regressing quickly over several days. In addition, we derived predictive equations using diameter and dry mass to estimate the number of days before, and after, ovulation for pre- and postovulatory follicles, as well as an equation to estimate dry mass of damaged follicles. Our results allow precise definition of RFG and nest initiation dates, clutch size, and the daily energetic and nutritional demands of egg production at the individual level. This study provides the necessary foundation for additional work on Greater Scaup reproductive energetics and physiology, and offers an approach for quantifying ovarian follicle dynamics in other species.