Breeding ecology of Yellow Wagtails Motacilla flava in an arable landscape dominated by autumn-sown crops

Capsule Yellow Wagtails successfully raised two consecutive broods in landscapes dominated by autumn-sown crops and did not require spring crops or fallow plots for later nesting.

Aims To assess whether arable landscapes dominated by winter cropping provide habitats that allow Yellow Wagtails to raise two successful broods. To assess the utility of spring cultivated agri-environment fallow plots as a nesting and foraging habitat for Yellow Wagtails.

Methods Nesting success and foraging behaviour of Yellow Wagtails was monitored on lowland arable farmland dominated by winter cropping during two successive breeding seasons.

Results Yellow Wagtails successfully raised first and second broods mainly in winter cereals, with later nests being more successful. Some nests were initiated in bean fields where egg-stage failure rates were high, probably as a consequence of depredation. Fallow plots were not used for nesting but, along with other areas of sparse vegetation, were regularly used for foraging.

Conclusions Yellow Wagtails breeding at relatively low densities achieved high rates of reproductive success in a landscape dominated by winter cereals and with few spring-sown crops. This study suggests that spring-sown crops may not be necessary for Yellow Wagtails to rear two successful broods each summer within arable landscapes.     

Breeding density of Dippers Cinclus cinclus' Grey Wagtails Motacilla cinerea and Common Sandpipers Actitis hypoleucos in relation to the acidity of streams in south-west Scotland

The distribution of breeding pairs of Dippers Cinclus cinclus , Grey Wagtails Motacilla cinerea and Common Sandpipers Actitis hypoleucos was assessed along 18 streams in south-west Scotland during summer 1987, and the lengths of territories, occupied by 5 5 breeding pairs of Dippers, were measured. In each stream the water chemistry, physical structure (e.g. gradient, altitude, nature of bankside vegetation) and density of aquatic invertebrates was determined. The density of breeding pairs of dippers was significantly lower along streams of low pH (high acidity) and steep gradients, and territories were significantly longer at these sites compared with those of higher pH. Many of the invertebrate families that are important prey for Dippers were scarce at sites of low pH, particularly caddisfly larvae (Trichoptera) and mayfly nymphs (Ephemeroptera). The low numbers and large territories of breeding pairs of Dippers on acidic streams may be due to reduced density and diversity of macroinvertebrate prey. Stream pH was not an important correlate of the distribution or density of Grey Wagtails or Common Sandpipers. It is suggested that the lack of any similar effect of pH on these other two species compared with Dippers is attributable to differences in their feeding ecology.     

Unusual finding of Trichobilharzia sp. in Motacilla alba in the Czech Republic

Adult male worms of Trichobilharzia sp. recovered from a pied wagtail (Motacilla alba) in the Czech Republic were found to belong to a new species of the genus. The finding of Trichobilharzia sp. in a passeriform bird in Europe represents an important discovery, as only anseriform birds have thus far been reported as final hosts of the European Trichobilharzia species.     

Experimentally elevated testosterone levels enhance courtship behaviour and territoriality but depress acquired immune response in Red Bishops Euplectes orix

The immunocompetence handicap hypothesis (ICHH) posits that the hormone testosterone mediates a trade‐off between investment in reproduction and immunological condition. In this study, we tested the ICHH in the Red Bishop Euplectes orix, a polygynous weaverbird. Males of this strongly sexually dimorphic species show an elaborate courtship display to attract females and compete aggressively with other males for nesting sites in breeding colonies. We experimentally elevated testosterone levels in breeding male Red Bishops kept in an aviary with a subcutaneous implantation of testosterone‐releasing pellets. We then compared behaviour, development of territory size and immunological condition (as assessed through a white blood cell count) of the experimental group with a control group treated with placebos. In addition, we measured the primary and secondary response to phytohaemagglutinin (PHA) to investigate the effect of testosterone on both innate and acquired immunity. Males with elevated levels of testosterone enlarged their territories and conducted more courtship behaviour, while showing a decrease in health, expressed by an increased heterophil/lymphocyte ratio compared with the control group. Males of the control group showed an increase of the secondary response to PHA, as expected under the assumption that repeated exposure to an antigen enhanced the immune response due to acquired immunity. However, males with experimentally increased testosterone levels did not show such an enhanced immune response in the secondary PHA test (although sample size and power of the statistical tests were low), indicating that testosterone treatment might directly or indirectly suppress some component of the acquired immune response.     

Extensive phenotypic diversification coexists with little genetic divergence and a lack of population structure in the White Wagtail subspecies complex (Motacilla alba)

Geographically clustered phenotypes often demonstrate consistent patterns in molecular markers, particularly mitochondrial DNA (mtDNA) traditionally used in phylogeographic studies. However, distinct evolutionary trajectories among traits and markers can lead to their discordance. First, geographic structure in phenotypic traits and nuclear molecular markers can be co‐aligned but inconsistent with mtDNA (mito‐nuclear discordance). Alternatively, phenotypic variation can have little to do with patterns in neither mtDNA nor nuclear markers. Disentangling between these distinct patterns can provide insight into the role of selection, demography and gene flow in population divergence. Here, we examined a previously reported case of strong inconsistency between geographic structure in mtDNA and plumage traits in a widespread polytypic bird species, the White Wagtail (Motacilla alba). We tested whether this pattern is due to mito‐nuclear discordance or discrepancy between morphological evolution and both nuclear and mtDNA markers. We analysed population differentiation and structure across six out of nine commonly recognized subspecies using 17 microsatellite loci and a combination of microsatellites and plumage indices in a comprehensively sampled region of a contact between two subspecies. We did not find support for the mito‐nuclear discordance hypothesis: nuclear markers indicated a subtle signal of genetic clustering only partially consistent with plumage groups, similar to previous findings that relied on mtDNA. We discuss evolutionary factors that could have shaped the intricate patterns of phenotypic diversification in the White wagtail and the role that repeated selection on plumage ‘hotspots’ and hybridization may have played.     

Group living, breeding behaviour and territoriality in the Subdesert Mesite Monias benschi

In 1997–2000 we studied a population of Subdesert Mesites Monias benschi consisting of 35–68 adults comprising 32 groups of two to nine birds (modal group size of four). The study population was significantly male-biased in 1999 but not in 1997 or 1998. Overall, both sexes were philopatric, but when dispersal (or eviction) occurred, it appeared to be female-biased. Over 40% of groups contained more than two adult males, whilst < 15% contained more than two adult females. Whilst there was no evidence of behavioural dominance by females, intrasexual aggression within groups was observed only amongst females. In contrast to other birds occupying the same habitat, breeding in mesites was not tied to rainfall, and occurred throughout the year. Each breeding unit constructed several nests every year, only one of which was used. All adult males and at least one adult female co-operated to raise one or two clutches of one or two eggs per year. Males and females contributed equally to incubation. Chick production and chick survival were not related to group size or territory size. Groups defended large, permanent, and multipurpose territories and all group members contributed to territory defence. Territory size was positively correlated with the number of males in groups, but not with overall group size. Territories were tightly packed with very few areas unoccupied. Transect surveys conducted throughout the narrow geographical range of this species revealed its presence in a range of semi-arid habitat types. Small groups were more likely to be detected in intact, high-stature forest, whilst large groups were more likely to be detected in low-stature forest containing numerous spiny, xerophytic trees Didierea madagascariensis .     

艾比湖大白鹭的繁殖及雏鸟生长发育模式

2009年3—10月对新疆艾比湖大白鹭(Egretta alba alba)的巢、卵及雏鸟的生长发育模式进行了研究。结果表明,大白鹭的巢基厚度大于巢深(t=6.06,P0.01),巢外径远大于巢内径(t=21.53,P0.01),其目的是增加巢的稳定性和减少幼鸟跌出巢外的概率;窝卵数3～5枚(3.86±0.69),卵重44.00～60.00g(53.94±3.96),卵体积47.18～62.00cm3(55.19±4.09);双亲孵卵(26～28d),共同育雏(55～60d)。测量了4巢13雏26日龄以内的生长发育数据,并利用Gompertz方程对雏鸟的主要生长指标进行拟合,拟合结果将雏鸟生长发育划分为3个阶段:1)器官形成,生长速度准备加快的时期;2)物质积累,生长速度加快并逐渐过渡到中速时期;3)由物质积累逐渐过渡到物质消耗大于积累,生长速度较慢,雏鸟准备出飞。     

Breeding season influxes and the behaviour of adult male samango monkeys (Cercopithecus mitis albogularis)

Troops comprising a high density population of samango monkeys (Cercopithecus mitis) in Natal province, South Africa, experienced an influx of adult males during the breeding season. Observation of one troop revealed that these males competed with one another and with two resident males for access to receptive females. Although both sexes initiated copulation, attempts to do so were more often successful if female-initiated. Males did not interact with non-receptive females and there were no recorded attempts at infanticide. Male-male interactions were agonistic in the presence of receptive females and neutral at other times. No ritualized displays of dominance and subordinance were seen. The significance of these observations for male reproductive strategies is discussed.     

Reproductive isolation between sympatric sister species,Mussaenda kwangtungensis and M. pubescens var. alba

Reproductive isolation de fi nes the biological species concept and plays a key role in the formation and maintenance of species. The relative contributions of different isolating stages has been suggested to be closely associated with phylogenetic relatedness. Few studies have focused on the relative contributions of pre- versus postzygotic mechanisms, and even fewer have been conducted under strict phylogenetic frameworks. Pre- and post-zygotic reproductive isolation stages have been investigated in the sister species Mussaenda kwangtungensis and M. pubescens var. alba. The two species have partly overlapping distribution ranges and fl owering times, while the principal pollinators differed strikingly for them, demonstrating strong pre-zygotic isolations. Natural hybrids were detected by simple sequence repeat markers and their maternal parents were identi fi ed based on chloroplast gene sequences. Five out of 81 individuals were suggested to be hybrids that fall into the categories F2, BC1, and BC2 by theNew Hybrids analysis. Interspeci fi c crossings resulted in signi fi cantly reduced fruit set and seed germination rates.Phylogenetic analysis revealed short Kimura-2-parameter distance between M. kwangtungensis and M. pubescens var.alba. These fi ndings strongly supported the hypothesis that for species with a closer phylogenetic relationship, prezygotic isolation plays an important part in limiting gene exchange in sympatric areas.     

Asymmetrical introgression between two Morus species (M. alba, M. rubra) that differ in abundance

Asymmetrical introgression is an expected genetic consequence of hybridization when parental taxa differ in abundance; however, evidence for such effects in small populations is scarce. To test this prediction, we estimated the magnitude and direction of hybridization between red mulberry (Morus rubra L.), an endangered species in Canada, and the introduced and more abundant white mulberry (Morus alba L.) using nuclear (randomly amplified polymorphic DNA) and cytoplasmic (chloroplast DNA sequence) markers. Parentage of 184 trees (n = 42 using cpDNA) from four sympatric populations was estimated using a hybrid index and related to six morphological characters and population frequencies of the parental classes. Overall, the frequency of nuclear hybrids was 53.7% (n = 99) and ranged from 43% to 67% among populations. The parental and hybrid taxa differed with respect to all of the morphological traits. Sixty-seven percent of all hybrids contained more nuclear markers from M. alba than M. rubra (hybrid index x = 0.46); among populations, the degree of M. alba bias was correlated with the frequency of M. alba. In addition, the majority of hybrids (68%) contained the chloroplast genome of white mulberry. These results suggest that introgression is bidirectional but asymmetrical and is related, in part, to the relative frequency of parental taxa.     

Orcadian rhythm of Oecophylla longinoda in relation to territoriality and predatory behaviour

Abstract Circadian rhythms of activity in four societies of Oecophylla longinoda (Latreille) have been studied. Activity is continuous, but diurnal activity is greater than the nocturnal activity. This species is characterized by a strong sense of territoriality and the workers occupy: central territories, trees and immediate surroundings occupied by the society; secondary territories, used for hunting purposes, in natural conditions located on the ground; and intermittent territories in the forest zone (diurnal), scarcely used for hunting, but mainly in relation to the tending of homopterans.
The circadian rhythm of activity can be reversed by artificially lighting certain territories at night (reinforcement by attraction of numerous prey). This reversal can only be obtained progressively. By permanent surveillance of the territories and efficient recruitment, the societies rapidly adapt to fluctuations in the quantity of prey. There is a close correlation between agressive territoriality and predation.     

Butterflyfish social behaviour,with special reference to the incidence of territoriality: a review

Synopsis Butterflyfishes (Chaetodontidae) are among the best studied of coral reef fishes. Feeding ecology and some aspects of behaviour have been firmly established. However, spacing behaviour remains controversial. Two major studies made in the 1970s concluded that the majority of species were not territorial. We suggest that these and other studies which have concluded that territories are not held have generally suffered from short observation periods, and have not mapped the ranges occupied by individuals. Further, low frequencies of agonistic behaviour have been interpreted as evidence of non-territoriality. By contrast, studies which have proven territoriality have had long observation periods and have mapped ranges. These have shown that territories are usually maintained with very little overt aggression. Spacing behaviour and feeding behaviour are clearly linked, with territoriality common among benthic-feeding species, especially obligate corallivores. Species with broad dietary flexibility tend to have flexible social systems, while plankton feeders are usually gregarious. The widespread occurrence of monogamy in butterflyfishes appears linked to territoriality, the majority of territorial species identified to date occurring predominantly as pairs. Data currently available suggest that this is because pair defence of the territory is more efficient than by individuals. However, several alternative hypotheses for the evolution of monogamy based on spawning constraints and predation risk cannot yet be ruled out.     

Breeding behaviour, home range and habitat selection in Rock Firefinches Lagonosticta sanguinodorsalis in the wet and dry season in central Nigeria

Knowledge of a species’ movement behaviour and habitat choice is a prerequisite for assessing its ecological requirements to plan successful conservation strategies. Little is known about these factors in the Rock Firefinch, a recently described species which is probably endemic to the Jos Plateau in central Nigeria. We investigated home range size, habitat use and breeding behaviour of the Rock Firefinch in Amurum forest reserve in central Nigeria during the wet (August–October) and the dry season (November–December) using radiotracking. Birds showed high site fidelity. They mainly moved alone or in pairs but did not have exclusive home ranges. Home range size tended to be larger during the dry season due to long movements to water sources. Birds generally preferred inselberg habitat and avoided farmland. During the dry season they additionally utilized gallery forests where water was readily available, and as a result of having to cross scrub savannah to get to water, scrub savannah was also more heavily used during the dry season. Birds bred between the late rainy (September–October) and the early dry season (November). Nest‐sites were associated with rocky boulders. Both sexes contributed to incubation. Daily egg survival rate calculated using the Mayfield method was 0.89 (0.83–0.95 95% confidence interval); no nests failed during the chick stage, but sample size was only four nests. Of all 14 nests found, 50% were depredated and only 29% of breeding attempts succeeded in producing Rock Firefinch chicks. A second breeding attempt was recorded when the first one failed. Chick production just about compensated adult mortality (measured in a separate study at the site) such that the population is probably stable at present. However, given the large uncertainty in our underlying assumptions, more data are needed to confirm this. We suggest that the presence of inselberg habitat in close proximity to water sources is the essential and limiting resource for this species.