家燕和金腰燕的卵胚胎心率比较

胚胎心率是衡量胚胎新陈代谢速率的重要指标。鸟类的胚胎心率随新陈代谢的增加而呈上升趋势。对早成性鸟类的种间比较发现,胚胎心率平均值随卵重量的增大而减小,卵体积小的种类具有相对较高的胚胎心率。国内有关野生鸟类胚胎心率的研究较少。2014年5~8月,在黑龙江扎龙国家级自然保护区,利用红外胚胎心率测量仪对两种近缘鸟类家燕(Hirundo rustica,n=14)和金腰燕(Cecropis daurica,n=14)的卵胚胎心率及其变化进行了测量与比较。两种燕均在孵卵的第2天开始出现胚胎心率,并随胚龄增加心率呈上升趋势,但在第8天及第11~14天家燕的胚胎心率显著低于金腰燕(第8天:z=﹣2.602,P=0.009;第11天:z=﹣2.497,P=0.013;第12天:z=﹣2.354,P=0.019;第13天:z=3.424,P=0.001;第14天:z=﹣3.380,P=0.001)。家燕卵胚胎日均增长心率(19.0±3.1)次/min,金腰燕卵胚胎日均增长心率(16.1±3.4)次/min,二者差异不显著(z=﹣1.792,P=0.073)。两种燕的胚胎心率与卵容量和卵重均不存在显著相关性[家燕:卵容量(1.73±0.09)cm3,r=0.192,P=0.511;卵重(1.74±0.09)g,r=0.128,P=0.663。金腰燕:卵容量(1.74±0.08)cm3,r=0.040,P=0.891;卵重(1.51±0.09)g,r=0.054,P=0.855]。这可能表明,卵大小和卵重量对家燕与金腰燕的胚胎心率均影响不明显。     

哈尔滨家燕mandschurica亚种繁殖生态特征

许多鸟种因具有较强的适应性而分布广泛,例如家燕(Hirundo rustica)。在不同纬度地区研究其繁殖生态学特征有助于了解家燕对不同环境的适应。家燕mandschurica亚种在国内仅分布于黑龙江省,且该亚种的繁殖资料少有报道,为此,于2016和2017年每年的4至10月,在哈尔滨对其繁殖生态特征开展研究,并与国内目前已发表的家燕gutturalis亚种繁殖生态特征进行对比。家燕mandschurica亚种4月底或5月初迁来哈尔滨,9月下旬或10月初南迁;窝卵数为4～6枚(n=19);卵长径(18.7±1.4)mm(15.9～22.5 mm)、卵短径(13.0±0.5)mm(12.2～14.2 mm),卵重(1.6±0.1)g(1.3～1.9 g),n=35;孵卵期为(16±2)d(14～18 d,n=19);育雏期为(17±1)d(16～18 d,n=6)。雏鸟的体长、翅长及尾羽长的生长曲线能与Logistic较好地拟合;体重、嘴峰和跗跖在5日龄左右生长最快,体长和翅长在7日龄左右增长最快,雏鸟的生长模式符合能量分配假说。与我国南方的家燕gutturalis亚种相比,在哈尔滨繁殖的mandschurica亚种的卵更小、更轻,二者孵卵期相似,但后者育雏期更短。这或许与不同地区食物丰富度及亲鸟喂食策略有关。     

Wait Until Dark? Daily Activity Patterns and Nest Predation by Snakes

Predation involves costs and benefits, so predators should employ tactics that reduce their risk of injury or death and that increase their success at capturing prey. One potential way that predators could decrease risk and increase benefits is by attacking prey at night when risks may be reduced and prey more vulnerable. Because some snakes are facultatively nocturnal and prey on bird nests during the day and night, they are ideal for assessing the costs and benefits of diurnal vs. nocturnal predation. We used automated radiotelemetry and cameras to investigate predation on nesting birds by two species of snakes, one diurnal and the other facultatively nocturnal. We predicted that snakes preying on nests at night should experience less parental nest defence and capture more adults and nestlings. Rat snakes (Pantherophis obsoletus) were relatively inactive at night (23–36% activity) but nearly always preyed on nests after dark (80% of nest predations). Conversely, racers (Coluber constrictor) were exclusively diurnal and preyed on nests during the times of day they were most active. These results are consistent with rat snakes strategically using their capacity for facultative nocturnal activity to prey on nests at night. The likely benefit is reduced nest defence because birds defended their nests less vigourously at night. Consistent with nocturnal predation being safer, rat snake predation events lasted three times longer at night than during the day (26 vs. 8 min). Nocturnal nest predation did not make nests more profitable by increasing the likelihood of capturing adults or removing premature fledging of nestlings. The disconnect between rat snake activity and timing of nest predation seems most consistent with rat snakes locating prey during the day using visual cues but waiting until dark to prey on nests when predation is safer, although designing a direct test of this hypothesis will be challenging.     

Do seasonal patterns of rat snake (Pantherophis obsoletus) and black racer (Coluber constrictor) activity predict avian nest predation?

Avian nest success often varies seasonally and because predation is the primary cause of nest failure, seasonal variation in predator activity has been hypothesized to explain seasonal variation in nest success. Despite the fact that nest predator communities are often diverse, recent evidence from studies of snakes that are nest predators has lent some support to the link between snake activity and nest predation. However, the strength of the relationship has varied among studies. Explaining this variation is difficult, because none of these studies directly identified nest predators, the link between predator activity and nest survival was inferred. To address this knowledge gap, we examined seasonal variation in daily survival rates of 463 bird nests (of 17 bird species) and used cameras to document predator identity at 137 nests. We simultaneously quantified seasonal activity patterns of two local snake species (N = 30 individuals) using manual (2136 snake locations) and automated (89,165 movements detected) radiotelemetry. Rat snakes (Pantherophis obsoletus), the dominant snake predator at the site (~28% of observed nest predations), were most active in late May and early June, a pattern reported elsewhere for this species. When analyzing all monitored nests, we found no link between nest predation and seasonal activity of rat snakes. When analyzing only nests with known predator identities (filmed nests), however, we found that rat snakes were more likely to prey on nests during periods when they were moving the greatest distances. Similarly, analyses of all monitored nests indicated that nest survival was not linked to racer activity patterns, but racer‐specific predation (N = 17 nests) of filmed nests was higher when racers were moving the greatest distances. Our results suggest that the activity of predators may be associated with higher predation rates by those predators, but that those effects can be difficult to detect when nest predator communities are diverse and predator identities are not known. Additionally, our results suggest that hand‐tracking of snakes provides a reliable indicator of predator activity that may be more indicative of foraging behavior than movement frequency provided by automated telemetry systems.     

海南睑虎种群密度调查研究

关于睑虎属Goniurosaurus物种的研究主要集中在新种描述和系统进化等方面,对种群密度量化的研究较少。为研究海南吊罗山国家级自然保护区海南睑虎Goniurosaurus hainanensis种群的资源现状,2019年7—9月,在保护区内选取2个不同海拔梯度的样区(A样区551～688 m和B样区289～448 m),采用标记重捕法对该物种的种群密度进行了调查,并分别采用Schnabel法和Lincoln指数法进行种群密度估算。结果显示:采用Schnabel法估算的种群密度A样区为501只/hm²,B样区为1 999只/hm²;采用Lincoln指数法估算的种群密度A样区为583只/hm²,B样区为1 403只/hm²。结果表明:该物种的种群密度随海拔升高呈下降趋势。     

AN INTRAPERITONEAL RADIO TRANSMITTER FOR SEA OTTERS

A small intraperitoneal radio transmitter was developed and used successfully in California sea otters. The transmitter weighs about 120 g and has an internal antenna. Thirty-five implanted transmitters were located for an average of 526 d. The carcasses of five animals that died were recovered; there were no complications associated with the transmitters in these individuals. Reproductive performance of the adult females with implanted transmitters appeared normal. The main advantages of this transmitter are its reliability and long life. It has enabled the collection of significant new information on California sea otters.     

澜沧江漫湾电站水库地区爬行动物多样性研究

漫湾电站水库地区有爬行动物４６种,隶属３目１０科３７属。特点是：（１）特种多样性很丰富,为中国扑行类种娄１１．８９％,为云南的３０．４６％,是云南省和全国爬行类很丰富的地区;（２）东洋界种类占绝对优势（９７．８３％）,没有古北界种类,古北东洋两界广布种仅１种;（３）西南区与华南区种类分别为２０及１９种;华中区及华中华南两区广布种很少;（５）特有种多,在我国主要产于云南有８种,占１７．３９％,其中云     

Segregation in the African wintering ranges of English and Swiss Swallow Hirundo rustica populations: a stable isotope study

Capsule Stable isotope analysis of Swallow feathers, grown in Africa, revealed significant differences between populations breeding in Switzerland and England.

Aims To investigate the extent to which Swallow populations breeding in Switzerland and England are separated on their African wintering grounds.

Methods Swallows were caught at breeding colonies, biometric measurements were taken and feathers, grown in Africa, were collected. Feathers were combusted in a Carlo Erba C/N/S analyser and the δ¹³C and δ¹⁵N signatures were measured using a mass spectrometer.

Results The δ¹³C signatures of Swiss birds were significantly more depleted than those of birds from England. The δ¹⁵N signatures did not differ between the two populations.

Conclusion Birds from Switzerland and England probably winter in geographically distinct parts of Africa. The Swiss birds probably feed on prey that are more reliant on C₃ vegetation, from woodlands, than the prey of English birds, which are more reliant on C₄ vegetation, from grasslands.