Correlation between two components of parental investment: nest defence intensity and nestling provisioning effort of willow tits

Nest defence intensity and nestling provisioning effort of female willow tits (Parus montanus) were significantly correlated at the end of nestling period: well-fed young were defended most intensely. Increased effort was rewarded, since broods with the highest female per-offspring provisioning rates were the most likely to produce local recruits. This suggests that the feeding ability is an important cue for parental investment decisions, at least in a species like the willow tit which has adopted the clutch adjustment strategy. Thus, the most valuable broods would not necessarily be the largest ones, but the ones in which the original number of young could be fed most adequately. However, no associations were found between the level of parental effort and offspring weight, size or condition, nor did the broods producing recruits differ from other broods in timing of breeding or number and size of offspring. The female behaviour may suggest that they invest the most time, energy and risk in the young whose chances of joining the winter flock are the best. The first well-fed young also gain an advantage of prior residency in joining the flock. The first to join normally obtain higher social status, and hence better winter survival, than latecomers. The corresponding patterns in male parental investment behaviour were weak or absent, which suggested that the male effort was affected by the female behaviour. Males seemed to invest in nestling provisioning in such a way as to supplement the female effort. During nest defence action males also seemed to invest in protection of females against predation.     

鸬鹚雏鸟的生长发育

对青海省青海湖国家级自然保护区内鸬鹚（Phalacrocorax carbo)雏鸟的生长发育进行了观察和研究。结果表明,在发育过程中,鸬鹚雏鸟跗足迹和嘴峰的发育早于翅和尾;通过体长与其它各生长指标的相对生长指数的计算。得出跗足迹和翅长的生长比体长快,嘴峰和尾长的生长比体长慢,另外,根据各生长指标特性的变化,将整个生长期划分为0-9日龄,10-23日龄,24-33日龄和34-离巢出飞4个生长阶段。     

窝雏数处理对两种雀形目幼鸟生长的影响

基于 1 997～ 1 999年野外实验 ,对高寒草甸小云雀和黄嘴朱顶雀两种雀形目鸟的窝雏数进行增减处理。结果表明 ,对照组的幼鸟生长率和离巢体重都大于增加组 ,说明窝雏数增加后 ,幼鸟质量下降。随着窝雏数增加 ,这两种幼鸟生长率显著下降 (小云雀 :r =-0 965 ,P =0 0 3 5 <0 0 5 ;朱顶雀 :r =-0 82 8,P =0 0 2 2 <0 0 5 )。窝雏数改变对小云雀幼鸟出飞重影响不显著 (r =-0 41 8,P =0 5 2 8>0 0 5 ) ,而对黄嘴朱顶雀有显著的影响 (r=-0 90 1 ,P =0 0 1 4<0 0 5 )。     

松鸦的繁殖生态

在安徽合肥紫蓬山区,对松鸦的繁殖生态进行了观察,并研究了雏鸟的生长发育特征。结果表明,松鸦4月初开始营巢,巢筑在阔叶树或针叶树主干顶端枝杈处,巢呈碗状,由细树枝、须根、苔藓和草编织而成。4月中下旬开始产卵,平均每窝产5枚卵,孵化期16－17d,育雏期19d。体重、嘴峰、翅、跗跖、尾、飞羽及飞羽羽缨等形态学参数适合用Logistic曲线方程拟合,对应的拟合方程分别为：W＝120／[1 e^-0.329(t-8.1)]、L=23/[1 e^-0.2011(t-4.5)]、L=107/[1 e^-0.334(t-9.1)]、L=40/[1 e^-0.293(t-4.5)]、L=49/[1 e^-0.377(t-13.7)]、L=76/[1 e^-0.462(t-12.4)]、L=49/[1 e^-0.544(t-17.8)]。曲线的增长率和拐点的参数分析表明,与飞行密切相关的器官在雏鸟发育的后期仍有较大程度的增长,而与取食相关的器官在雏鸟早期就有较大程度的发育。     

Biometry based ageing of nestling Indian Spotted Owlets ( Athene brama brama)

Biometric analysis helps in sex differentiation, understanding development and for studies of avian biology such as foraging ecology, evolutionary ecology, and survivorship. We suggest that biometry can also be a reliable, practical and inexpensive tool to determine the age of nestlings in the field by non-invasive methods. As an example we studied the biometry of wing, culmen, talon, tarsus and body mass of nestling southern Indian Spotted Owlets (Athene brama brama). Based on the growth pattern analysis using logistic growth model, discriminant analysis and CHAID (Chi-squared Automatic Interaction Detection) based decision tree, we show that biometry of nestling Spotted Owlets is an easy, reliable and inexpensive method to determine nestling age and to assess growth rate and relative nutritional status. These biometric parameters also allow us to predict their ability to initiate first flight from the nest site. This method is described here for the first time and we postulate that such charts can be devised for other avian species as well, so as to assist conservation biologists and bird rescuers.     

Sex differences in DHEA and estradiol during development in a wild songbird: Jugular versus brachial plasma

Sexual differentiation of the brain has traditionally been thought to be driven by gonadal hormones, particularly testosterone (T). Recent studies in songbirds and other species have indicated that non-gonadal sex steroids may also be important. For example, dehydroepiandrosterone (DHEA) - a sex steroid precursor that can be synthesized in the adrenal glands and/or brain - can be converted into active sex steroids, such as 17β-estradiol (E₂), within the brain. Here, we examine plasma DHEA and E₂ levels in wild developing European starlings (Sturnus vulgaris), from hatch (P0) to fledging (P20). Blood samples were collected from either the brachial vein (n = 143) or the jugular vein (n = 129). In songbirds, jugular plasma is enriched with neurally-synthesized steroids and, therefore, jugular plasma is an indirect measure of the neural steroidal milieu. Interestingly, brachial DHEA levels were higher in males than females at P4. In contrast, jugular DHEA levels were higher in females than males at P0 and P10. Brachial E₂ levels were higher in males than females at P6. Surprisingly, jugular E₂ levels were not high and showed no sex differences. Also, we calculated the difference between brachial and jugular steroid levels. At several ages, jugular steroid levels were lower than brachial levels, particularly in males, suggesting greater neural metabolism of circulating DHEA and E₂ in males than females. At a few ages, jugular steroid levels were higher than brachial levels, suggesting neural secretion of DHEA or E₂ into the general circulation. Taken together, these data suggest that DHEA may play a role in brain sexual differentiation in songbirds.     

Reproductive success and nestling diet in the Lesser Spotted Woodpecker ( Picoides minor ): the early bird gets the caterpillar

Populations of Lesser Spotted Woodpecker (Picoides minor) are decreasing in size, necessitating management strategies. However, data on the reproductive biology of this species are scarce. The aim of this study was to investigate the influence of timing of breeding and nestling diet on the reproductive success of the Lesser Spotted Woodpecker and thereby contribute to an understanding of the determinants influencing its reproductive success. During 6 study years between 1996–2003, we investigated various variables of reproductive success in a Lesser Spotted Woodpecker population in the Taunus low mountain range, Germany. We observed nestling feeding at breeding holes to assess the composition of nestling diet and how it changes during the season. Clutch size, number of fledglings as well as body mass of the nestlings declined with the start of egg laying. Pairs composed of individuals that had breed together in previous years started egg laying earlier than newly established pairs. Nestling diet consisted mainly of aphids, caterpillars, craneflies and wood-living larvae. The composition changed considerably within the breeding season in both early and late broods. However, early broods were provided with caterpillars more frequently, whereas late broods received wood-dwelling larvae more often. Our results suggest that Lesser Spotted Woodpeckers time their breeding so as to coincide with the early nestling stage with the highest availability of caterpillars, since this is the time of highest energy demand. Moreover, food availability declines during the breeding season, and the decline in reproductive performance seems to be an effect of this development.     

三种鹭异步孵化与雏鸟生长的比较研究

根据1996～1999年的野外工作和实验饲养,研究了池鹭、白鹭、夜鹭3种鹭的繁殖、雏鸟生长和异步孵化对雏鸟生长的影响.3种鹭于4月上、中旬迁到常山、余杭鹭保护区,9月下旬陆续迁离.孵卵期池鹭为23.0 d(n=26),白鹭23.9 d(n=32),夜鹭25.3 d(n=34);孵化率池鹭为76.32%,自鹭86.96%,夜鹭95.45%,池鹭繁殖力为3.21只,白鹭3.38只,夜鹭3.50只.雏鸟体重增长与成体体形大小呈负相关.幼雏体重增长与孵化顺序相关.在生长早期(≤8 d)全部雏鸟正常发育,之后差异显著.第1和第2孵化雏鸟生长曲线相似,但明显高于第4雏鸟,表明较早孵化者获得食物能力较强,而迟孵出雏鸟有食物不足现象.该3种鹭孵育幼雏能力的最适度估计为3只左右.     

家燕的繁殖生态及雏鸟生长发育

20 0 4年3～1 0月对南充地区家燕(Hirundorustica)的繁殖生态进行了观察,研究了雏鸟生长发育模式。结果表明,家燕2月中旬迁来,9月中旬迁飞。一般年产卵2窝。4月初已见产卵,卵长径(1 9 1 8±0 90 )mm ,短径(1 4 1 8±0 41 )mm ,卵重(2 5 7±0 3 8)g。孵卵期(1 6±1 )d ,育雏期2 2～2 3d。雏鸟体长及外部器官的形态学参数可以用Logistic曲线方程很好地拟合,体长、翅长及1 3日龄前的体重增长曲线均呈“S”型。     

黄腹山鹪莺育雏行为和雏鸟生长

2007年3~9月,在广东省肇庆市江溪村对黄腹山鹪莺(Prinia flaviventris)的育雏行为和雏鸟生长进行了研究。通过取食行为观察、育雏食物分析和雏鸟身体量度的测量来研究黄腹山鹪莺亲鸟繁殖投资和雏鸟的生长规律。研究期间,利用隐蔽帐观察窗进行行为观察,观察距离在5 m以内;在雏鸟身体上用无味彩笔标号以区别雏鸟个体:10日龄前,标记于雏鸟背部,10~12日龄,标记在雏鸟跗跖处;对部分数据进行双变量相关分析,利用Logistic曲线拟合雏鸟形态增长,并比较每个回归方程斜率间的差异。结果显示:1)黄腹山鹪莺育雏由雌雄共同承担,育雏期(11.9±0.4)d(n=7巢)。幼雏出壳后亲鸟早晚暖雏,第7天起亲鸟白天不再暖雏;2)随雏鸟的生长,喂食次数和食物种类逐渐增加,雏鸟日龄与喂食次数极显著相关(r=0.995,P0.01);3)育雏期雏鸟食物皆为动物性食物,以蜘蛛目物种所占比例最大(40.95%),其他包括幼虫及直翅目、鳞翅目、鞘翅目、蜻蜓目等节肢动物;4)Logistic曲线方程中,体重的生长率常数k值最大,与其他k值之间存在显著性差异(P0.05);5)黄腹山鹪莺体重、体长、尾长、翼长、嘴峰、嘴裂、第三根初级飞羽(简称为P3)、跗跖及爪各参数间的相关系数均为0.9以上(P0.01),参数之间在一定程度上可相互代替;6)黄腹山鹪莺雏鸟的发育遵循最重要的功能优先发育的原则,符合能量分配假说。黄腹山鹪莺喂食次数、雏鸟生长速率(k值)相对较高,可能与当地丰富的食物资源有关,也可能是对巢址环境多变的适应。