青海北部高寒草甸雀形目鸟类繁殖生态学的研究进展

从鸟巢特征、巢址选择、窝卵数、育幼行为、雏鸟生长发育、繁殖生产力以及繁殖对策等方面,对青藏高原高寒草甸雀形目鸟类繁殖生态学进行了综合分析与评述。高寒草甸雀形目鸟类受适合繁殖季节长度、食物资源和捕食压力的影响,或选择逐步投资对策,或选择一次投资对策;每个种群的常见窝卵数就是最适窝卵数;雏鸟的发育模式相对固定,不存在补偿性生长,但是生长期长度是可变化的。①研究亲-子通讯行为的进化和稳定性,提出适应高寒草甸雀形目鸟类的亲-子间的通讯行为假设;②建立在巢环境特征变化梯度(开放到封闭)上的生命表,找出决定适合度的生命表参数(繁殖率和存活率)的因果关系;③测定在巢环境特征变化梯度上的生态领域变化将是未来研究的3个方向。     

高寒草甸十种雀形目鸟类繁殖生物学的研究

本文主要将作者1976年至1980年收集的高寒草甸10种常见的小型雀形目鸟类的繁殖特性作一概述,并对繁殖参数和影响繁殖的某些因素作一初步分析。此外,有关鸟类繁殖的许多指标,如种群中参加繁殖的雌体比例、繁殖期、产卵数、成活率等都是估测通过鸟类群落能量流的重要参数。因此,有关繁殖指标的数据将按估测能量流的要求处理(Wiens,1974),以供高寒草甸鸟类能量流的估测作为参考。     

高寒草甸植物群落中物种丰富度与生产力的关系研究

 以物种组成较为复杂的青藏高原东部地区典革高寒草甸植物群落为背景,从不同的时间和空间尺度水平研究了植物群落中物种丰富度与生产力（地上部生物量）关系的基本模式。结果表明：1）总体而言,高寒草甸植物群落中物种丰富度与生产力的关系呈对数线性增加关系,这实际上是空间和时间尺度放大时在时间和空间尺度的相互作用下高寒草甸植物群落中物种丰富度与生产力关系的一种总体模式;2）随着研究的时间和空间尺度的改变,物种丰富度与生产力的关系会发生一些相应的变化,但空间尺度比时间尺度对物种丰富度与生产力的关系造成的影响更为显著,这可能     

不同生境下珠芽蓼（蓼科）的繁殖策略比较

在青藏高原横断山区以海拔相同的高山流石滩和高寒草甸中的珠芽蓼（Polygonum viviparum）居群为研究对象,探讨该物种在不同生境条件下的繁殖策略以及无性繁殖和有性繁殖间的关系。结果发现,流石滩居群的珠芽蓼植株高度和珠芽数量显著低于高寒草甸居群,而珠芽和花总数量、花数量和每个花序上的花比例却显著高于高寒草甸居群。研究结果表明珠芽蓼在环境更为恶劣的高山流石滩生境中增加了对繁殖器官和花资源的投资,说明在高山植物中繁殖优先于营养生长,且有性繁殖比无性繁殖具有更为重要的作用。而对每个植株上花数量和珠芽数量的统计结果表明,两者呈显著的负相关关系,进一步证明了同一植株内无性繁殖和有性繁殖的权衡关系。     

青藏高原高寒草甸生态系统的恢复能力

近年来,青藏高原高寒草甸生态系统呈现退化的趋势.本文利用中国科学院海北高寒草甸生态系统定位站多年观测的长时间序列数据,采用定量方法度量高寒草甸自然生态系统的恢复能力,评估该系统的持久性,并结合系统现状提出避免系统崩溃的对策.结果表明,高寒草甸净初级生产力的动态行为以对降水和气温的即时直接响应为主.无论是净初级生产力对自身的"记忆"程度,还是主要气候因子对初级生产力的"滞后"作用,均比较微弱,说明高寒草甸生态系统有较强的恢复能力,即有较强的持久能力.与世界其他地区草地生态系统恢复能力度量结果相比较,高寒草甸生态系统显示较强的恢复能力.科学地利用高寒草地资源,积极恢复治理退化草地,是维持脆弱的高寒草甸生态系统持久的关键.     

乌鲁木齐市不同生境繁殖期的鸟类群落多样性及功能集团分析

2016—2019年对乌鲁木齐市7种生境(高寒草甸、针叶林-灌丛、草原、农田、荒漠、湿地和城市公园)的繁殖期鸟类进行实地调查。共记录鸟类178种,隶属19目45科,其中雀形目Passeriformes最具代表性,共86种(占48.3%);居留型以夏候鸟和留鸟为主,共153种(占86.0%);分布型以古北型为主,共82种(占46.1%);珍稀濒危和重点保护物种共33种(占18.5%)。鸟类群落物种数及个体数最多的为湿地生境,荒漠、针叶林-灌丛生境次之,各生境物种数(H=30.628,P0.001)存在显著性差异。湿地生境鸟类的Shannon-Wiener多样性指数最高,高寒草甸生境的最低;草原生境的Pielou均匀度指数最高,高寒草甸生境的最低;高寒草甸生境的Simpson优势度指数最高,草原生境的最低;针叶林-灌丛生境的物种丰富度指数最高,荒漠生境的最低。草原与针叶林-灌丛生境之间的Sorensen相似性系数最高(0.59),高寒草甸与荒漠之间的最低(0)。湿地生境鸟类群落的捕食集团以食虫性为主,其他生境以杂食性为主。湿地生境中鸟类营地面巢的居多,高寒草甸生境中鸟类营洞巢的居多,其他生境中鸟类营编织巢的居多。上述结果表明,乌鲁木齐市周围的湿地生境应该得到优先保护。     

鸟类群落对若尔盖高原湿地退化梯度的响应

鸟类是湿地生态系统重要的一类环境指示生物,研究其群落特征对湿地退化的响应,有助于揭示湿地生态系统结构和功能的变化、探讨对湿地状况进行有效监测和评价的方法。以若尔盖湿地国家级自然保护区花湖、兰州大学高寒草甸与湿地生态系统定位研究站（阿孜站）为研究区域,2018年5、2019年5月采用样线法对区域中4种高原湿地退化梯度,即典型湿地（Ⅰ型）、季节性湿地（Ⅱ型）、中度退化湿地（Ⅲ型）和重度退化湿地（Ⅳ型）的繁殖鸟类群落进行调查研究。研究时段共记录到繁殖鸟类8目14科41种,其中花湖繁殖鸟类39种,阿孜站繁殖鸟类21种。数据分析显示,随着高原湿地退化演替序列,两地的鸟类群落物种数和多样性指数均逐步减小,群落优势度不断增大;Ⅲ型和Ⅳ型群落相似性系数最高,Ⅰ型和Ⅳ型间群落相似性最低,表明鸟类群落随湿地退化发生明显改变,仅与毗邻的退化梯度群落组成相似。研究区域Ⅰ型生境中,水禽类占绝对优势,以红脚鹬（Tringa totanus）为优势种;Ⅱ型中长嘴百灵（Melanocorypha maxima）为群落中优势种;小云雀（Alauda gulgula）和角百灵（Eremophila alpestris）为Ⅲ型群落中的优势种;群落中优势种团为雪雀（Montifringilla spp.）和地山雀（Pseudopodoces humilis）时,标志着湿地已经重度退化（Ⅳ型）。鸟类群落优势种的转变是鸟类营巢环境要求与湿地退化中环境的改变相适应的结果。本研究尝试性的提出如何利用鸟类对高原湿地退化状态进行监测和评价。     

高寒草地类型和海拔对濒危藏药独一味生长繁殖特征的影响

为探讨高寒草地类型和海拔对独一味(Lamiophlomis rotata)生长与繁殖特征的影响,在玛曲三种草地类型和三个海拔梯度下进行随机样方调查和样品收集,并对独一味的生长和繁殖特征指标进行测定。结果表明:(1)不同草地类型中,独一味地上部特征表现为高寒沼泽化草甸高寒山坡草甸高寒灌丛草甸,地下部特征表现为高寒沼泽化草甸高寒灌丛草甸高寒山坡草甸;(2)独一味生长繁殖特征随着海拔的升高而下降;(3)不同草地类型和海拔下,独一味有性繁殖结构的投入与植株大小间存在显著的正相关性,而无性繁殖投入与植株大小间不存在相关性;(4)不同草地类型和海拔下,独一味两种繁殖方式间不存在相关性。综上结果表明:独一味资源分配方式受到草地类型影响,是与环境长期适应后的结果;有性繁殖的发生需要植株一定量的营养生长积累,而无性繁殖投入可能是植株固有特性,与植株大小无关;根茎芽无性繁殖可能发生在地上部破坏之后而非主动行为,两种繁殖方式间的无相关性是否会受到除草地类型和海拔以外的其他因素影响还有待进一步研究。     

青海省海北地区高寒草甸鸟类群落结构的季节变化

本研究地区,高寒草甸鸟类群落由22种鸟组成,它们隶属于2目9科,其中留鸟11种,迁徙鸟8种。在当地繁殖的鸟19种,冬候鸟2种。各项鸟类群落指标呈现明显季节变化,一般从早春开始上升,到夏季达到高峰,然后逐渐下降至隆冬的最低点。     

降水量变化对藏北高寒草地养分限制的影响

生态系统净初级生产养分限制的模式是现代生态学关注的重要问题。养分的可利用性是草原生态系统生产力动态变化的关键决定因素, 但土壤养分可利用性与整个生态系统中养分限制之间的关系尚不清楚。该研究通过在藏北降水梯度上4种类型高寒草地(从东到西依次是高寒草甸、高寒草甸草原、高寒草原和高寒荒漠草原)设置氮磷养分添加试验, 系统研究氮磷养分添加对不同类型高寒草地的影响, 并探讨降水梯度上高寒草地的氮磷限制模式。结果表明: (1)氮磷添加对不同高寒草地的影响存在差异: 氮添加显著提高了高寒草甸和高寒草甸草原地上生产力, 而对高寒草原和高寒荒漠草原无影响; 单独磷添加对4种高寒草地均无显著影响, 而氮磷添加对4种高寒草地地上生产力均有促进作用。(2)通过计算氮磷共同限制指数发现: 随着降水量减少, 高寒草地氮限制指数从1.18逐渐降低到0.52-0.64, 养分限制模式从氮限制过渡到氮磷共同限制; 磷限制指数在高寒草甸草原和高寒草原为负值, 说明单独磷添加对高寒草甸的生产力有负向作用, 高寒草甸主要受氮限制; 高寒草甸草原介于氮限制与氮磷限制之间, 受到氮磷共同限制, 单独磷添加有负向作用; 高寒荒漠草原受到氮磷共同限制。研究表明, 高寒草地氮磷限制模式存在环境梯度上的递变规律, 随着降水量减少, 高寒草地养分限制模式从氮限制逐渐过渡到氮磷共同限制。由此推断, 未来气候变化条件下氮沉降增加对不同类型高寒草地的影响可能存在差异。同时, 利用养分添加恢复不同类型退化高寒草地时也应将氮磷限制模式的差异考虑进去。     

Annual and seasonal reproductive trends in the Lesser Spotted Woodpecker Dendrocopos minor

Annual and seasonal variation in reproductive timing and performance were studied in a population of the Lesser Spotted Woodpecker Dendrocopos minor over 10 years in southern Sweden. The median laying date of the first egg varied by up to 17 days between years, being generally larger than the variation of laying dates within years. Neither clutch size, brood size in successful nests, fledging success in successful nests nor mean nestling weight differed significantly between years. There was no trend for mean clutch size to vary between early and late years. In spite of a more than threefold variation in population size, no reproductive variable demonstrated an apparent density-dependence. Within the season, clutch size declined steeply with increasing clutch initiation date, whereas fledging success and nesting success did not, leading to a trend in brood size almost identical to the trend in clutch size. The survival prospects of fledged young declined with increasing clutch initiation date, and it is argued that the clutch size laid is a strategic adjustment to laying date. Out of 124 breeding attempts, 34% did not produce fledged young. In 9% of the breeding attempts, pairs laid no eggs. At least 20% of the breeding attempts failed after egg-laying. The most common cause of breeding failure was loss of the breeding partner followed by nest abandonment (40% of the failures). Only 16–28% of the failures were due to predation on the nest. Most complete failures, and also partial losses from nests, occurred at the early breeding stages. It is argued that the early nestling phase may be a critical stage, which the woodpeckers adjust to coincide with the seasonal food peak, explaining the strikingly late breeding season compared with other non-migrant species.     

Breeding ecology of Styan's Bulbul Pycnonotus taivanus in Taiwan

The breeding ecology of Styan's Bulbul Pycnonotus taivanus , an endemic species in Taiwan, was studied in Kenting, Taiwan. The duration of the breeding season of Styan's Bulbul stretched from March to July in 1983. The average clutch size was 3.3 eggs ( n =34), and hatching success was 60%. The average number of nestlings at hatching was 2.7 per clutch, and 73% of the young fledged. Styan's Bulbuls selected their nest sites among dense vegetation. In the study area, 75% ( n =84) of nests were found in the Indiapoon Beautyleaf tree Calophyllum inophyllum , which had a relative vegetation density of only 33.5%. Factor analysis was used to analyse 13 nest-site characteristics of 63 nests, and five factors accounted for 69% of the variation.     

Sprague's pipit breeding biology and reproductive success in planted and native grasslands

Much of the native grasslands in agricultural regions have been converted to cropland or tilled and seeded with non‐native grasses for livestock production. Several grassland songbird species occupy planted grasslands, but occupancy or density may not be a reliable indicator of habitat quality. I studied the breeding biology of Sprague's pipit Anthus spragueii from 2004 to 2008 in Saskatchewan, Canada. My objective was to determine the extent to which the breeding biology, density and reproductive success of pipits varied in planted and native grasslands. Peak clutch initiation occurred in mid‐ to late‐May in planted and native grassland. Peak pipit density also occurred in May, but density drastically declined over the breeding season in planted grassland. Clutch size varied among years and declined over the breeding season, but was similar in planted (4.7  0.1 SE) and native grasslands (4.5  0.1 SE). Daily nest survival rates varied with age of the nest and date, but the relationships differed in the two habitats and was likely a result of lower nestling survival in planted grassland compared to native grassland. The number of young fledged per nest increased as the season progressed and tended to be greater in native (1.2  0.1 SE) than planted (0.9  0.2 SE) grasslands. Seasonal productivity was much greater in native grassland. Only three nests were initiated after May in planted grassland and all were unsuccessful, whereas pipit young fledged at higher rates from nests initiated in native grassland in June and July than planted grassland nests initiated in May. The number of fledged young from successful nests did not vary strongly with habitat, date or year. This research indicates that planted grasslands attract pipits at the beginning of the breeding season, but habitat suitability and reproductive success substantially declines as the breeding season progresses compared to that found in native grassland.     

Density-dependent decline of breeding success in an introduced, increasing mute swan Cygus olor population

An increasing population of the mute swan Cygnus olor , was studied from its very establishment in 1976 until 1998. As the number of pairs increased, there was a decline in all production parameters, including the average number of clutches per pair, the average number of broods per clutch, and the average number of fledged young per brood. In a multiple regression analysis covering the whole breeding season, the number of pairs and the average number of clutches per pair explained 71% of the variation in the average number of fledglings per pair. During the brood season, the average number of fledglings per brood was an additionally important parameter in explaining fledgling production. Habitat quality seemed to affect breeding: in places occupied earlier more cygnets fledged from a clutch than in habitats inhabited later. The decreased production of young very likely reflects density-dependent effects on reproduction. This density dependence seems to operate on the breeding grounds, since winter harshness did not affect breeding success. Density-dependent processes started acting already when pairs were beginning to nest, and continued during the brood period. Density dependence has apparently not been detected at the pair stage in earlier studies of bird populations.     

9. LIST OF MEMBERS (as at date of publication)

We studied the breeding ecology of the Chestnut-backed Sparrowlark Eremopterix leucotis over three years between 2008 and 2010. The breeding season was bimodal with a main peak in laying in autumn (March–April) and another smaller peak in spring (September–October). Nest microhabitat analyses showed they prefer nesting in open areas with lots of bare ground (median 67.5%). Nest entrance directions were biased towards the south (mean vector (µ) = 186.44°). The majority of nests (78.2%) had an apron at the nest entrance. The mean clutch size was 1.88 but there was geographic variation in clutch size between northern and southern races of the species. The mean incubation and nestling periods were 10.33 d (range 10–11 d) and 9.20 d (range 8–10 d), respectively. The results suggest that parental contributions during incubation are almost equal, but females made significantly more food deliveries during the nestling period compared to males. The diet of nestlings comprised mainly of invertebrates (50.2%), seeds (34.4%) and unidentified food items (15.4%). Breeding success was low, averaging 16.1% (range 8.1–20.6%), and the average number of fledged young per pair was 0.36 ± 0.71. Replacement broods were common and we also recorded repeat brooding attempts.     

The Impact of Increased Food Availability on Reproduction in a Long-Distance Migratory Songbird: Implications for Environmental Change?

Many populations of migratory songbirds are declining or shifting in distribution. This is likely due to environmental changes that alter factors such as food availability that may have an impact on survival and/or breeding success. We tested the impact of experimentally supplemented food on the breeding success over three years of northern wheatears (Oenanthe oenanthe), a species in decline over much of Europe. The number of offspring fledged over the season was higher for food-supplemented birds than for control birds. The mechanisms for this effect were that food supplementation advanced breeding date, which, together with increased resources, allowed further breeding attempts. While food supplementation did not increase the clutch size, hatching success or number of chicks fledged per breeding attempt, it did increase chick size in one year of the study. The increased breeding success was greater for males than females; males could attempt to rear simultaneous broods with multiple females as well as attempting second broods, whereas females could only increase their breeding effort via second broods. Multiple brooding is rare in the study population, but this study demonstrates the potential for changes in food availability to affect wheatear breeding productivity, primarily via phenotypic flexibility in the number of breeding attempts. Our results have implications for our understanding of how wheatears may respond to natural changes in food availability due to climate changes or changes in habitat management.     

Breeding success and chronology of Wood Storks Mycteria americana in northern and central Florida, U.S.A.

The breeding success and chronology of Wood Storks Mycteria americana were studied at eight colonies in northern and central Florida during 1981–1985. Mean ± s.d. clutch size for all colony-years was 3.07 ± 0.56 (n = 2694 nests), with three-egg clutches (72%) most frequent. Mean clutch size among all colonies and years ranged from 2.73 ± 0.55 to 3.41 ± 0.61. Many colonies exhibited significant negative trends in clutch size with, hatching date because of a proportional decrease in four-egg clutches later in the season. Mean colony clutch size was not correlated with nest numbers, nesting density or mean hatching date within most years. Mean ± s.d. number of fledglings for all colonies and years was 1.29 ± 1.16 fledglings per nest (n = 2812 nests). Mean annual fledging rates in colonies ranged from 0 (colony failed) to 2.66 fledglings per nest. Most breeding failure occurred prior to egg hatching, and the second highest mortality occurred between hatching and 2 weeks of age. Four-egg clutches fledged more storks than three-egg clutches, which in turn were more successful than two-egg clutches. However, all clutch sizes showed similar fledgling per egg rates. The seasonal decline in productivity was associated proportionally with smaller clutch sizes later in the breeding season. An increase in mean hatching date was correlated with an increase in latitude. There was greater within-year breeding synchrony among colonies than interyear breeding synchrony within each colony. Breeding synchrony was not correlated with mean hatching date, latitude, longitude, nest numbers or nesting density.     

The breeding biology of the Common Crossbill Loxia curvirostra in the Central Pyrenees

The breeding biology of the Common Crossbill Loxia curvirostra was studied over ten consecutive years in forests of Mountain Pine Pinus uncinata in the Pyrenees, France. The breeding season lasts from summer to the next spring following the maturation and the opening of the pine cones. Pairs with dependent young were most common in November and March–May. The greatest number of clutches was observed in December and January (53%, n = 30). Average clutch size was 3.43 eggs (sd = ±0.57; n = 30), the number of fledged young was 1.32 per completed clutch (sd = ±1.7; n = 25) and the proportion of breeding attempts that were successful was 27.8% in the winter/spring period (n = 36). The number of successful pairs was found to be positively correlated to the number of cones, and in the winter/spring period negatively correlated to the mean depth of snow. Breeding only failed completely during the year in which the density of birds was highest. In years with a good cone crop, breeding that starts early and continues over a long period appears to be an adaptation which increases productivity in this sedentary population dependent on fluctuating food resources. An irruption by birds from northern Europe in 1990 did not affect the numbers or breeding success of the Pyrenean crossbills.     

Intrapopulation variation in reproduction by female eastern kingbirds Tyrannus tyrannus: the impacts of age, individual performance, and breeding site

I used data from a 13-year study of eastern kingbirds Tyrannus tyrannus from central New York, USA, to evaluate the relative impact of female age and body size on reproduction. I also calculated repeatabilities of reproductive traits for both females and the sites where they bred in an attempt to evaluate the relative contribution of each to intrapopulation variation in reproduction. Female age had a strong influence on timing of breeding (breeding date advanced by one day for each year of life), but was not a significant source of variation for clutch size, egg mass, number of young to hatch or fledge, or total seasonal production. Repeatabilities of breeding date for females and sites were both significant (0.284 and 0.181, respectively), but the only other significant repeatabilities were for female clutch size (0.282) and female egg mass (0.746). Among-year repeatabilities of breeding date for females who bred at two or more sites over their lifetime were as high as those for females that were site faithful. Thus, breeding date was probably affected independently by the female and site. No measure of productivity exhibited a repeatable pattern in comparisons made among females or sites. All reproductive traits were entered as dependent variables in a series of stepwise multiple regression analyses in an attempt to identify female properties (size, lifespan and condition) that might be linked proximately to differences in breeding statistics. I found that (a) large birds tended to breed the earliest, (b) clutch size was independent of female size, condition and lifespan, (c) female body size and egg size were correlated positively, but (d) production of young was independent of all measured female properties. Reproduction appears to be linked more closely to the female than to the site. Body size accounts for a portion of the repeatable portion of breeding date and egg mass, but most of the intrapopulation variation in these and other traits remained unexplained.     

Geographical variation in reproductive investment across avian assemblages in Europe: effects of environmental drivers differ between altricial and precocial species

Reproductive traits provide information about the ways by which available resources are allocated during breeding. We tested for environmental drivers of large scale geographical patterns in assemblage mean clutch size, number of broods and overall reproductive investment per breeding season in European birds. We combined data about geographical distribution with published information about reproductive traits, and calculated mean trait values for avian assemblages occurring in 50 × 50 km grid cells. In total, we employed data from 499 species and 2059 assemblages. As the time available for breeding and the amount of food limit the reproductive effort, we related the geographical variation in reproductive traits to the length of breeding season, normalized difference vegetation index (NDVI) as a surrogate of resource availability, and its seasonality. Geographical patterns in traits may differ between reproductive modes, thus we performed the analyses separately for altricial Passerines (n = 203) and precocial non‐passerine species (n = 164) and controlled for the effect of taxonomy. Large clutches dominated in areas with high NDVI and, in precocial birds, also in areas with high annual seasonality and a long breeding season. High number of broods and high overall reproductive investment dominated in areas with a long breeding season, and high number of broods was found also in areas with low annual seasonality, but only in precocial species. High overall reproductive investment dominated in highly productive areas and also in areas with low annual seasonality in both groups. The increase in reproductive investment is caused mostly by an increase in the number of broods related to the length of season and partly by increase in clutch size related to NDVI. We found a negative correlation between clutch size and the number of broods in Passerines, which might suggest a trade‐off between these traits. Processes behind trait patterns differ between altricial and precocial species.