Vocal individuality of large-tailed nightjar (Caprimulgus macrurus) in Peninsular Malaysia

All four nightjar species resident in Peninsular Malaysia are vocally distinct, yet they remain little studied. Conventional field methods based on visual cues to study diurnal species may be impractical for nightjars. Alternatively, aural survey can potentially be applied on nightjars provided that individuality in their vocalisations can be proven. Our study aimed to determine the vocal individuality of the common, large-tailed nightjar (Caprimulgus macrurus) in oil palm smallholdings and an isolated forest patch located in Selangor, Peninsular Malaysia. From the call recordings obtained from 22 individuals, results of the Kruskal-Wallis analysis revealed significant differences in all the nine vocal parameters (call length, interquartile range bandwidth, low, high, average, centre and peak frequencies as well as first and third quartile frequencies) measured among individual nightjars (p < 0.001) regardless of study sites. Discriminant Function Analysis showed that more than 94.5% of original grouped cases were correctly classified. This implied that the majority of vocalizations can be assigned to individual birds based on the parameters measured. This study demonstrated the occurrence of vocal individuality in the large-tailed nightjar and such a finding pertaining to distinct vocalisations at the individual level will compensate for the limited access to visual cues in field surveys, as with the case for all nocturnal birds.     

Habitat use of nightjar (Caprimulgus europaeus) in an Austrian pine forest

The Steinfeld in Lower Austria supports a population of European Nightjar (Caprimulgus europaeus) which was extensively studied during 1997 and 1998. The study area encompassed a pine forest of 20 km². The population densities of 1.05 and 1.25 territories/km², respectively, lies within the range found in central European populations. Annual monitoring until 2001 has shown the population to be stable. To gain an insight into habitat use of the species, various habitat-related parameters were measured inside and outside the territories, namely structure of trees, density of trees, structure of undergrowth vegetation and structure of clearings. Discriminant analysis was applied to assess the factors responsible for habitat choice of the Nightjar population. The findings showed that the Nightjars territories were frequently centered on a large clearing with an area of at least 0.7 ha. Clearings less than 50 m wide were not colonized. The requirement for a minimum width of a clearing in addition to a minimum area probably relates to better hunting conditions. Nightjars prefer trees where the lower edge of the crown is on average 4.38 m higher than at control points so that males can churr from dead branches immediately below the canopy. Such trees were found on the edge of clearings in the forest, and the edge of a clearing thus had a pronounced effect on the quality of a territory. In contrast to reports in the literature, neither the proportion of bare patches of ground nor the average height of undergrowth vegetation was found to be decisive for territory selection.     

Ultrastructure of the spermatid of Caprimulgus europaeus Linnaeus 1758, the European nightjar (Aves; Caprimulgidae), with phylogenetic implications

The sperm of Caprimulgus europaeus is typical of other nonpasserines in many respects. Features shared with Paleognathae and Galloanserae are the conical acrosome, shorter than the nucleus; the presence of a perforatorium and endonuclear canal; the presence of a proximal as well as distal centriole; the elongate midpiece with mitochondria grouped around a central axis (here maximally six mitochondria in approximately 10 tiers); and the presence of a fibrous or amorphous sheath around the principal piece of the axoneme. A major (apomorphic) difference from paleognaths and galloanserans is the short distal centriole, the midpiece being penetrated for most of its length by the axoneme and for only a very short proximal portion by the centriole. Nonpasserines differ from paleognaths in that the latter have a transversely ribbed fibrous sheath, whereas in nonpasserines it is amorphous, as in Caprimulgus, or absent. The absence of an annulus is an apomorphic feature of Caprimulgus, apodiform, psittaciform, gruiform, and passerine sperm, homoplastic in at least some of these. In contrast to passerines, in Caprimulgus the cytoplasmic microtubules in the spermatid are restricted to a transient longitudinal manchette. The structure of the spermatid and spermatozoon is consistent with placement of the Caprimulgidae near the Psittacidae, but is less supportive of close proximity to the Apodidae, from DNA-DNA hybridization and some other analyses.     

Migration strategies and annual space‐use in an Afro‐Palaearctic aerial insectivore – the European nightjar Caprimulgus europaeus

Obligate insectivorous birds breeding in high latitudes travel thousands of kilometres during annual movements to track the local seasonal peaks of food abundance in a continuously fluctuating resource landscape. Avian migrants use an array of strategies when conducting these movements depending on e.g. morphology, life history traits and environmental factors encountered en route. Here we used geolocators to derive data on the annual space‐use, temporal pattern and migratory strategies in an Afro‐Palaearctic aerial insectivorous bird species – the European nightjar Caprimulgus europaeus. More specifically, we aimed to test a set of hypothesises pertaining to the migration of a population of nightjars breeding in south‐eastern Sweden. We found that the birds wintered across the central and western parts of the southern tropical Africa almost entirely outside the currently described wintering range of the species. The nightjars performed a narrow loop migration across Sahara, with spring Sahel stopovers significantly to the west of autumn stops indicative to an adaptive response to winds during migration. To our surprise, the migration speed was faster in the autumn (119 km d^{? 1}) than in the spring (99 km d^{? 1}), possibly due to the prevailing wind regimes over the Sahara. The estimated flight fraction in both autumn (14%) and spring (12%) was almost exactly as the theoretically predicted 1:7 time relationship between flights and stopovers for small birds. The temporal patterns within the annual cycle indicate that individuals follow alternative spatiotemporal schedules that converge towards the breeding season. The positive relationship between the spatially and temporally distant winter departure and breeding arrival suggests that individuals´ temporal fine‐tuning to breeding may be constrained, leading to potential negative fitness consequences.     

Study on the foraging behaviour of the European nightjar Caprimulgus europaeus reveals the need for a change in conservation strategy in Belgium

Effective nature conservation requires coherent actions based on the best available evidence concerning protected species. Recent studies have suggested that European nightjars Caprimulgus europaeus forage outside their recognized breeding habitats, yet, for Flanders (northern Belgium) information on nightjar foraging behaviour and key foraging habitats is lacking. To assess whether the foraging ecology of nightjars in Flanders is similar to that observed in other parts of Europe, we studied the crepuscular behaviour of this species in Bosland (northeastern Flanders) during a five‐year radio telemetry study. Tracking of 48 individuals within a coniferous forest was standardized and home ranges were calculated using a kernel density estimator (fixed kernel). Habitat use was investigated by comparing kernel placement to available habitat. Average maximal foraging distance was 2603 ± 1094 m and home ranges extended up to 691 ha. We identified the key foraging habitats to be extensively‐cultivated grasslands and recreational areas, areas that were previously assumed unsuitable for Belgian nightjars. Our results indicate the importance of foraging sites outside the breeding territory, confirming the findings of previous studies performed elsewhere in Europe. Incorporating our findings into future conservation plans could, therefore, lead to improved efficiency of EU conservation measures, designed for the protection of this bird species in Flanders.     

Comparison of the two rupicolous nightjars: the Afrotropical Freckled Nightjar Caprimulgus tristigma and the Neotropical Blackish Nightjar C. nigrescens

The Freckled Nightjar Caprimulgus tristigma and the Blackish Nightjar C. nigrescens are widespread and common within their rupicolous habitat, in the Afrotropics and Neotropics respectively, and may therefore be considered as successful in their adaptation to this habitat, a niche that has not been exploited by any other nightjar species. However, apart from a plumage pattern that matches a rocky substrate, their known life histories provide no common factors to explain this adaptive success. The factors that they do share are common to most other nightjars. While they nest and roost on rocks, their breeding biology is remarkably different. The contrasts and lack of convergence are surprising, and suggest that these two species are not as closely related as their current congeneric status implies. This is supported by recent molecular studies that place the African and South American Caprimulgus species in different well-supported clades.     

Voice-printing of the Nightjar, Caprimulgus europaeus

The usual way of analysing bird-song is by use of a conagraph, which produces a plot of frequency as a function of time, for perods of up to about 2.5 s. This method is fully described by Catchpole (1979), Jellis (1977) and Thorpe (1961). In the present work, a Brüel and Kjaer Narrow Band Spectrum Analyser was used to analyse up to two minutes of bird-song. This instrument produces a fast Fourier analysis of the input in the form of a spectrum of sound pressure level against frequency. Studies of seven Nightjars. Caprimulgus europaeus . show that each individual produces its own characteristic voice spectrum enabling individual birds to be identified with much greater ease than from a sonagram.     

Primate Torpor:Regulation of Stress-activated Protein Kinases During Daily Torpor in the Gray Mouse Lemur,Microcebus murinus

Very few selected species of primates are known to be capable of entering torpor. This exciting discovery means that the ability to enter a natural state of dormancy is an ancestral trait among primate...     

哺乳动物的蛰眠: 类型、物种分布与模式

哺乳动物的蛰眠(包括冬眠、夏眠和日蛰眠等)是最具吸引力的生命现象之一,是动物应对寒冷、食物
短缺、干旱等不良环境条件的适应策略之一。冬眠生理学(生态学) 研究具有重要的理论和实际意义。国际学
术界在该领域发展比较迅速,国内发展相对缓慢。本文从哺乳动物蛰眠的季节和持续时间、蛰眠期间所利用能
量的来源和贮存方式、启动蛰眠的信号来源等方面综述了哺乳动物蛰眠的类型;介绍了蛰眠的哺乳动物物种的
系统学分布;并对温带或北极动物的冬眠和冬眠阵及其各阶段的体温和代谢率变化特征、日温剧烈波动环境下
的冬眠特征以及日眠和日眠阵等方面进行了概括介绍,以期能促进国内相关领域的发展。     

Torpor in birds: taxonomy, energetics, and ecology

Recent reports on patterns and occurrence of torpor and other natural hypothermic states in birds have prompted a revision of many longstanding opinions. For instance, a larger assortment of birds covering a wider range of body mass than previously recognized uses energy-conserving mechanisms in the face of abundant food supplies. Thus, although acute energetic stress triggers the occurrence of hypometabolic states in many birds, energy deficits can no longer be regarded as the sole stimulus for avian torpor. Additionally, the phenology of this phenomenon (phases, duration, depth) shows more interspecific variation than previously appreciated, and traditional concepts of the phases of torpor are not always adequate. Hence, inclusive definitions of torpor based on physiological and/or behavioral criteria have become more difficult to formulate. However, average nighttime body temperature, which is highly consistent throughout the class Aves (38.54 degrees +/- 0.96 degrees C, n = 202), provides a convenient reference for detecting natural hypothermic states. Of the putative ecological factors associated with avian torpor, food specialization seems a prime candidate as an ultimate factor in the occurrence of this state in birds. With few exceptions, all of these animals capable of torpor are either frugivorous, nectarivorous, or insectivorous, suggesting a correlation between thermoregulatory pattern and predictability of food supply. To date, no clear answer exists as to whether the variety of thermoregulatory patterns evident in birds involves discrete mechanisms or merely steps in a physiological continuum. However, I suggest that the occurrence of differences in torpor patterns among closely related species (e.g., within families) favors the latter interpretation.     

Moult in adult Fiery-necked Nightjars Caprimulgus pectoralis ringed on Ranelia Farm,Cashel, Zimbabwe

Nothing has been published on the moult of the Fiery-necked Nightjar Caprimulgus pectoralis in Zimbabwe. However, most of the birds handled on Ranelia Farm, Cashel, during a study of nightjar breeding biology over four seasons, were examined for moult. Fiery-necked Nightjars were examined on over 70 occasions. Their annual moult occurs between late October and early March, commencing with the primaries, which moult descendantly. The secondaries, which moult ascendantly, follow after P5 has been shed, and so do the rectrices, which moult centrifugally, but R5 precedes R4. Body moult, which starts about the time that R1 is shed, progresses from the head across the neck to the rest of the dorsal plumage, and then over the throat and flanks to the ventral surface. The rictal bristles moult descendantly in time with the primaries. Several birds, some with primary moult scores as high as 18, had commenced moult while still tending young from the first brood, or incubating the eggs of a second, or replacement, clutch. The moult season overlaps the breeding season by about two months.     

Torpor and ultradian rhythms require an intact signalling of the sympathetic nervous system

During entrance into torpor heart and respiration rates are greatly reduced in parallel with the reduction of metabolic rate, suggesting an involvement of parasympathetic control. We compared the effect of parasympathetic inhibition with the effect of sympathetic inhibition on spontaneous torpor behaviour in the Djungarian hamster. Hamsters were acclimated to short photoperiod and displayed their standard torpor pattern as observed from T_b records. Parasympathetic inhibition was achieved by a subcutaneous implant of 21-day release pellets with Atropine and the sympathetic noradrenergic pathway was inhibited with a single injection of 6-Hydroxydopamine. Atropine treatment did not affect the occurrence and quality of spontaneous daily torpor at all. However, the reversible sympathetic inhibition by 6-Hydroxydopamine injection resulted in a complete disappearance of torpor for about 6 days. These results conclude that the onset of daily torpor requires an intact noradrenergic signalling of the sympathetic nervous system. We further observed that parasympathetic as well as sympathetic blockade resulted in an immediate abolishment of ultradian rhythms of body temperature. This suggests that the expression of ultradian oscillations in body temperature require a continued interaction of sympathetic and parasympathetic activity.     

Torpor, thermal biology, and energetics in Australian long-eared bats (Nyctophilus)

Previous studies have suggested that Australian long-eared bats (Nyctophilus) differ from northern-hemisphere bats with respect to their thermal physiology and patterns of torpor. To determine whether this is a general trait of Australian bats, we characterised the temporal organisation of torpor and quantified metabolic rates and body temperatures of normothermic and torpid Australian bats (Nyctophilus geoffroyi, 7 g and N. gouldi, 10 g) over a range of air temperatures and in different seasons. The basal metabolic rate of normothermic bats was 1.36 ± 0.17 ml g⁻¹ h⁻¹ (N. geoffroyi) and 1.22 ± 0.13 ml g⁻¹ h⁻¹ (N. gouldi), about 65% of that predicted by allometric equations, and the corresponding body temperature was about 36 °C. Below an air temperature of about 25 °C bats usually remained normothermic for only brief periods and typically entered torpor. Arousal from torpor usually occurred shortly after the beginning of the dark phase and torpor re-entry occurred almost always during the dark phase after normothermic periods of only 111 ± 48 min (N. geoffroyi) and 115 ± 66 min (N. gouldi). At air temperatures below 10 °C, bats remained torpid for more than 1 day. Bats that were measured overnight had steady-state torpor metabolic rates representing only 2.7% (N. geoffroyi) and 4.2% (N. gouldi) of the basal metabolic rate, and their body temperatures fell to minima of 1.4 and 2.3 °C, respectively. In contrast, bats measured entirely during the day, as in previous studies, had torpor metabolic rates that were up to ten times higher than those measured overnight. The steady-state torpor metabolic rate of thermoconforming torpid bats showed an exponential relationship with body temperature (r ² = 0.94), suggesting that temperature effects are important for reduction of metabolic rate below basal levels. However, the 75% reduction of metabolic rate between basal metabolic rate and torpor metabolic rate at a body temperature of 29.3 °C suggests that metabolic inhibition also plays an important role. Torpor metabolic rate showed little or no seasonal change. Our study suggests that Australian Nyctophilus bats have a low basal metabolic rate and that their patterns of torpor are similar to those measured in bats from the northern hemisphere. The low basal metabolic rate and the high proclivity of these bats for using torpor suggest that they are constrained by limited energy availability and that heterothermy plays a key role in their natural biology. Accepted: 22 November 1999     

普通夜鹰的繁殖习性及雏鸟的生长发育

2007年5～6月,对1窝普通夜鹰的繁殖习性及雏鸟的生长发育进行了观察.普通夜鹰育雏期约为18 d.雌、雄性都参与孵卵和育雏.育雏期每天有3个喂食高峰期,分别是晚上20:00～22:00、凌晨0:00~2:00、早上4:00~6:00.育雏过程中,亲鸟的领域性弱,护雏性强.初级飞羽在雏鸟出壳6 d后长出,但生长速度最快.     

Torpor during the reproductive season in a free-ranging subtropical bat, Nyctophilus bifax

During times of energetic stress many small mammals reduce their body temperature and metabolic rate, a state known as torpor. Whereas torpor is effective in energy conservation it also entails costs, such as reduced foetal development in pregnant females. Because it is currently not known how subtropical bats deal with energetic challenges during the reproductive season, the thermal biology of free-ranging non-reproductive male and pregnant female Nyctophilus bifax was examined during spring. Males entered torpor much more frequently than pregnant females. However, night time activity periods were similar in both sexes. My results show that even in the subtropics torpor is used regularly during the reproductive period in spring by non-reproductive male N. bifax to conserve energy, but is used rarely by pregnant females likely to prevent slowed foetal development.     

Identification of different song types in the European Nightjar Caprimulgus europaeus

ABSTRACT

Capsule: Two distinct song types were identified for male European Nightjars Caprimulgus europaeus with their relative frequency of use changing through the breeding season, indicating a possible link to paired status.

Aims: To test whether two song types could be defined in audio recordings and whether use differed in relation to the paired status of males.

Methods: Unattended acoustic recording devices were placed at a Nightjar study site in Nottinghamshire, United Kingdom, and recordings of churring vocalizations were made during two periods of the breeding season. These recordings were then analyzed to identify the presence/absence of the song terminal phrase and associated audible features.

Results: Two distinct song types were identified in the recorded audio data that differed in their terminal phrasing and overall song duration. The number of Nightjar songs with a terminal phrase increased significantly between the two sampling periods, from lower levels during the site arrival period, to higher levels during the first clutch initiation period.

Conclusion: This study showed that the use of Nightjar song types appears to vary through the breeding season, with males being more likely to produce song with a terminal phrase during the first clutch initiation period, when they are more likely to be paired or in the presence of a female. The unattended acoustic recording method may provide a minimally intrusive means of assessing the number of Nightjar breeding pairs and not just singing males.     

Structural and functional adaptation to display in the Standard-winged nightjar Macrodipteryx longipennis

The display of the Standard-winged nightjar is described and figured. In display flight of the male the "standards" (the greatly elongated second primaries) are lifted nearly vertically above the wing, and it is probable that this is achieved aerodynamically as well as muscularly.     

Matching Gas Exchange in the Bat from Flight to Torpor

SYNOPSIS. Many microchiropteran bats can reduce their metabolicrate three orders of magnitude during heterothermic torpor.This extraordinary range provides a unique insight into theadaptability of mammalian ventilatory control and function.To enable powered flight, bats have developed the highest capacitygas exchange system among mammals. However, starving duringwinter may account for the greatest mortality among bats thathibernate, thus imposing a strong selective pressure to decreasemetabolic cost during torpor. This high capacity gas exchangesystem must therefore operate efficiently at very reduced rates,despite conflicting mechanical constraints imposed by an enormousfunctional overhead. The bat surmounts this dilemma by adjustingits control strategy to breathe intermittently during torpor.This allows instantaneous breathing rates and tidal volumesnear predicted optimal levels. In addition, a passive oxygeninflux coupled with a high acidotic tolerance facilitates longerintervals between the breathing bouts. The acidotic tolerancesupports the endurance of these apneas because the passive effluxof carbon dioxide does not match the rate of oxygen influx.The acidotic tolerance further helps by allowing carbon dioxideto enrich the alveolar gas during apnea to levels above thatof a nonacidotic, continuous pattern of breathing. Thus, thebat's carbon dioxide load can be cleared in fewer breaths whenbreathing resumes. By efficiently controlling a high capacitygas exchange system to meet the minuscule demands during torpor,the bat demonstrates how physiological control strategies canadapt to overcome limitations imposed by conflicting selectionpressures.