Breeding success of a Lesser Spotted Woodpecker Dendrocopos minor population

We made intensive observations of 50 pairs of Lesser Spotted Woodpecker Dendrocopos minor in southern Sweden from 1989 to 1992. Between 7% and 22% of the pairs each year defended a territory but laid no eggs. Overall, 76% of the pairs laying eggs raised fledglings, but this proportion was only 33% in 1991 when the weather was cold and wet. The mean clutch size (5.9) and brood size (4.5) in successful nests did not vary significantly between years. Incubation time was 1 day longer in 1991 (11–12 days) than in 1990 and 1992 (10–11 days). Number of young fledged per nesting attempt (3.5) and per pair (2.7) in the population also varied significantly between years. The initiation of egg laying varied between years but coincided each year remarkably well with the date when oak came into leaf. Breeding success is discussed, and comparisons are made with other hole-nesting species.     

Behaviour and breeding biology of the cooperatively breeding Grey-backed Fiscal Shrike Lanius excubitorius in Kenya

Grey-backed Fiscal Shrikes Lanius excubitorius were studied over a 2j year period near Lake Naivasha, Kenya. Grey-backs are cooperative breeders, with group sizes ranging from two to II. Only one pair breeds per group, with all other group members aiding in the rearing of young. The study population ranged from 64 to 79 individuals that occurred in from 13 to 16 groups. Non-breeding helpers made up to 66% of the population, with male helpers being more numerous overall than females. The annual survival rate was 65%, with no differences detected between the survival of males and females, or of breeders and helpers. Only male helpers were observed to acquire breeding status within the natal territory. Some female helpers acquired breeding positions in territories adjacent to their natal territories. Group territorial displays occurred throughout the year but were most pronounced prior to breeding during rainy periods. Reproductive success was very low, with only 14.5% of the recorded breeding attempts leading to fledged young. Large groups (four or more birds) had greater reproductive success than small groups, but many factors other than, or in addition to, group size may have influenced this pattern. The breeding male contributed the most food to the incubating female and to the nestlings. Male helpers and the breeding female contributed more to nestlings than did female helpers. Observations on the post-fledging period indicate that socialization and establishment of dominance may be of importance in group-living species living in a restricted ecological and social setting.     

Philopatry, Dispersal Patterns and Nest-site Reuse in Lesser Grey Shrikes (Lanius minor)

To nest in the same breeding area, territory or even nest-site in successive years may provide a possibility to look at mechanisms involved in breeding habitat selection and could also be an important tool for conservation, management and restoration attempts. In this study we examine site fidelity towards the breeding area as well as the nesting site in a dense and stable population of the Lesser Grey Shrike Lanius minor, a long-distance migrant and highly endangered passerine species, at its present northern border of its breeding range. Overall we recovered 48 out of 146 (32.8%) adults between 1996 and 2000. Recovery rate is significantly higher for males (31 of 77, 40.25%) than for females (17 of 69, 24.6%). Recovery rate of nestlings is much lower since only 51 of 790 (6.5%) were recovered and there is no significant sex difference. Furthermore, our results from 1989 to 2000 revealed that more than 30% (97/319) of the nests were built in the same nest tree in successive years and more than half (183/319 = 57.4%) of the nests in the same or neighboring trees (up to 20 m), but very seldom by the same individuals. The fact that nest reuse in successive years is almost exclusively done by different individuals suggests habitat copying and public information of individual birds. Due to optimal ecological breeding conditions other parameters like inbreeding avoidance or increased genetic variability could be important factors in nest-site selection strategies and consequently result in a “disperse over stay strategy”.     

虎纹伯劳的巢生境选择与繁殖行为

2005年3~7月通过焦点动物取样法(focal animal sampling)和完全记录法(all-occur rencerecording)对四川南充地区虎纹伯劳的繁殖行为进行了研究。结果表明,虎纹伯劳喜在5~12m的高大阔叶乔木的冠部分叉处营巢。对15个巢址主成分分析表明,前5个主成分特征值均大于1,累积贡献率高达83.15%,说明前5个主成分已经基本包含了所有参数的总信息量。4月下旬开始陆续有虎纹伯劳迁到,初到时并未配对。5月上旬开始出现求偶行为,并伴有递食行为。5月中旬首次见到营巢,两性参与营巢,营巢期5~7d。营巢结束一两天后开始产卵,一天一枚,窝卵数4~6枚。营巢期和产卵期都有求偶和交配行为。产完最后1枚卵后即开始由雌鸟单独孵卵,孵卵期13~14d。两性育雏,育雏期13~15d。     

Territoriality,breeding biology and vocalisations of the Crimson-breasted Shrike

This study reports on aspects of the territoriality, breeding success and vocal behaviour of Crimson-breasted Shrikes Laniarus atrococcineus at a study site in the Nylsvley district, South Africa. Their mean territory size was c. 12ha. Breeding success was very low, with only one nestling fledging from 13 clutches. Vocalisations consisted of eight different notes: these notes were either heard as solitary calls or combined into different types of duets. Both solitary calls and duets were heard more frequently outside the breeding season. During nest-building and incubation, the shrikes were silent, but resumed calling and duetting after the chicks had hatched. Call repertoires and the time spent calling or duetting differed among pairs of shrikes.     

Monitoring the world population of the Lesser Grey Shrike (Lanius minor) on the non-breeding grounds in southern Africa

Summary The world population of the Lesser Grey Shrike funnels in from breeding grounds in Eurasia to an area that is ten times smaller on the non-breeding grounds in the thornbelt of southern Africa, chiefly in the Kalahari basin. The species is abundant in open savanna habitat on the non-breeding grounds, where it is regularly spaced in individual territories and behaves conspicuously as a perch hunter. It has declined considerably during the last 200 years, and the non-breeding grounds offer highly favourable conditions for assessing and monitoring the world population. Extrapolation according to vegetation types of stratified survey data across southern Africa indicates a world population of 6.1 million birds (95% confidence 5.0–7.3 million) during the mid 1990s. However, for sensitive monitoring, the establishment of a standard-effort index is more appropriate than the assessment of the total population.

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Monitoring der Weltpopulation des Schwarzstirnwürgers(Lanius minor) im südafrikanischen Überwinterungsgebiet

Zusammenfassung Die Weltpopulation des Schwarzstirnwürgers konzentriert sich im nördlichen Winter in dem zum eurasiatischen Brutgebiet zehnmal kleineren Gebiet der Dornbuschsteppen des südlichen Afrikas, hauptsächlich das Kalahari Becken. Dort kommt die Art vornehmlich in der offenen Savanne vor, wo sie territorial ist und typischerweise Stoßjagd von Ansitzen aus macht. Die Art hat in den letzten 200 Jahren stark abgenommen. Die hohe Konzentrierung im Überwinterungsareal erlaubt ein Monitoring der Weltpopulation. Die Weltpopulation wird nach dortigen Zählungen auf etwa 6,1 Millionen Vögel (5.0–7.3 Million; 95% Vertrauensbereich) geschätzt. Für ein regelmäßiges Monitoring des Bestandes wird die Einrichtung von Beobachtungstransekten empfohlen.

     

Parasite Pressure and its Effects on Blood Parameters in a Stable and Dense Population of the Endangered Lesser Grey Shrike

The risk that pathogens and parasites pose to endangered species is increasingly evident. Nonetheless, this is frequently overlooked when considering causes of decline of species and conservation practices. Here, we study the ecto and haemoparasites of adult and nestling Lesser grey shrikes Lanius minor from a dense and stable breeding population in central Europe and their effect on host blood parameters. We found three species of haemoparasites (Haemoproteus sp., microfilariae tentatively assigned to the family Splendidofilariae and Trypanosoma sp.) and two ectoparasite taxa (Menacanthus camelinus and feather mites – Acarina-). Our data suggest that the studied population, located in an area with traditional and extensive farming, is not under a strong parasite pressure. Despite this, indirect measures of immunocompetence (haematocrit and sedimentation rate) showed an association between haemoparasites and health status: while haematocrit did not differ between parasitised and non-parasitised individuals, adult shrikes with haematozoa had significantly lower sedimentation rates than did non-parasitised birds.     

Function of courtship feeding in the Bull-headed Shrike,Lanius bucephalus

We investigated the frequency of courtship feeding (CF) in the Bull-headed Shrike (Lanius bucephalus) during the 1981–1982 breeding seasons. Because no CF was observed just prior to, during or just after copulation, CF is not associated directly with copulation and does not function as a releaser for copulation. The absence of CF during the pair-formation period of the early breeder and the high frequency of CF behavior in the cold season and in the critical breeding stages (egg-laying and incubation stages) for females strongly suggests that the significance of CF in this species is not symbolic but substantial at least in early breeders. We assign one of the causes of this CF to the early onset of breeding.     

Parental genetic characteristics and hatching success in a recovering population of Lesser Kestrels

Decreased hatchability is a common consequence of inbreeding in oviparous organisms and it has been generally considered a useful measure of the effects of reduced genetic diversity on embryological development. Here, we examined the pattern of hatching failure in a wild population of the endangered Lesser Kestrel (Falco naumanni). Particularly, we first analyzed long-term changes of hatching failure over a 16-year study period (1991–2006), in which the study population experienced a concurrent demographic and genetic recovery, and then we determined the consequences of parental genetic characteristics on hatching success. Long-term data analyses revealed a significant decline of hatching failure over time, with annual average hatching failure decreasing from rates characterizing species that have passed a severe population bottleneck to levels generally reported for outbred bird populations. Partial purging of deleterious recessive alleles after the species population decline, the increase of heterozygosity over time reported in a previous study and/or the selection for efficient mechanisms of inbreeding avoidance could be responsible of the observed temporal pattern. In contrast to previous studies, we found no effect of parental genetic characteristics on hatching success. Even though we analyzed an extensive dataset, the 11 neutral markers typed may have had low power to detect such an association. Further, this analysis was limited to the last 5 years (2002–2006) of the whole study period, when DNA samples for genetic analyses were available. During these years, hatching rates were like those typically reported for non-inbred populations, suggesting that the absence of association could be explained by a reduction of the genetic load or consequence of the genetic recover reported in the study population in recent years.     

The role of natural habitats in agricultural systems for bird conservation: the case of the threatened Lesser Grey Shrike

Birds of agricultural systems are one of the most threatened groups of birds in Europe mainly due to their sharp population decline in recent decades. Habitat intensification resulting from more productive agricultural practices has been proposed as a major cause for these declines. However, especially in some regions such as Eastern European and Mediterranean countries, little is known about the ultimate factors linked to habitat intensification that drive population declines for different species. The Lesser Grey Shrike is a good study species for a better understanding of such processes since it is closely related to agricultural habitats in Europe and has suffered a strong decline in range and population size across the western half of the continent. In this study, we explored variations in breeding parameters of this shrike related to habitat composition and food supply at the territory level. We found that fledgling success of early breeders was related to the presence of natural (shrub lands) and semi-natural (fallows) habitats in the predominantly agricultural matrix that dominated breeding territories. Their influence on fledgling success appeared to be mediated by a higher arthropod availability on these habitats. Indeed, Lesser Grey Shrike showed a strong preference for these habitats as hunting locations. Our results highlight the importance of natural habitats in intensified agricultural land mosaics for the conservation of bird species. We suggest that management plans should pay special attention to the availability of habitats which serve as high quality food reservoirs and can potentially contribute to enhance the species population viability in an area. Finally, we discuss the possible link between agricultural intensification and Lesser Grey Shrike population declines in Western Europe.     

Avian poxvirus epizootic in a breeding population of Lesser Flamingos (Phoenicopterus minor) at Kamfers Dam, Kimberley, South Africa

Avian pox has a worldwide distribution, but prior to this investigation has not been reported in free-ranging flamingo populations. During observations of the first successful breeding of Lesser Flamingos on a purpose-built island, at Kamfers Dam near Kimberley, South Africa, multiple small, raised, crusted plaques on the legs and facial area were noticed on 30% of the fledgling flamingos. A diagnosis of avipoxvirus infection was made on the basis of the macroscopic, histologic, and electron microscopic features, and was further confirmed by DNA sequence analysis. The avipoxvirus detected was very similar to that previously detected in albatross and falcons.     

Impact of Nesting Mortality on Avian Breeding Phenology: A Case Study on the Red-Backed Shrike (Lanius collurio)

The seasonal timing of avian reproduction is supposed primarily to coincide with favourable feeding conditions. Long-term changes in avian breeding phenology are thus mostly scrutinized in relation to climatic factors and matching of the food supplies, while the role of nesting mortality is largely unexplored. Here we show that higher seasonal mean daily mortality rate leads to a shift in the distribution of breeding times of the successful nests to later dates in an an open-nesting passerine bird, the red-backed shrike Lanius collurio. The effect appeared to be strong enough to enhance or counteract the influence of climatic factors and breeding density on the inter-annual variation in mean hatching dates. Moreover, the seasonal distribution of reproductive output was shifted to larger, or smaller, broods early in the season when the nesting mortality increased, or decreased, respectively, during the season. We suggest that population level changes in timing of breeding caused by a general advancement of spring and of the food supplies might be altered by the seasonality in nesting mortality. Hence, we argue that consideration of nesting mortality is of major importance for understanding long-term trends in avian phenology, particularly in species capable of renesting.     

Seasonal change in Red-backed Shrike Lanius collurio territory quality - the role of nest predation

This paper examines the relationships between territory preference, reproductive performance and nest predation in a Red-backed Shrike Lanius collurio population breeding in rapidly changing farmland. Territory preference was measured by (a) the order of laying dates in territories within years and (b) territory occupation frequency over a five-year period. Seven environmental variables were tested but only the density of Sloe (Blackthorn) Prunus spinosa in territories was correlated positively with territory occupation frequency. Within years, Red-backed Shrikes started to breed earlier in territories with more Sloe, but reproductive performance was not related consistently to territory differences. A high proportion of Sloe-rich territories was vacant each year. Thus, the observed negative association between settlement order and amount of Sloe may reflect a seasonal change in habitat preference. Early breeders prefer Sloe-rich territories whereas late birds prefer Sloe-poor territories. Supporting evidence is that the proportion of occupied territories that was Sloe-rich was higher for early than for average or late first breeding attempts. Moreover, in contrast to early in the season, the probability of a replacement clutch following nest failure was not associated with the amount of Sloe, but increased with increasing densities of Juniper Juniperus communis. Late in the nesting season, pairs breeding in Sloe-rich territories suffered higher nest predation than those breeding in Sloe-poor territories. In early nesting attempts, however, the relationship was reversed. Nest predation is probably an important selective agent on habitat selection since it was the principal factor explaining variation in the numbers of fledglings produced among territories. Thus, the Red-backed Shrike may shift territorial preferences adaptively as the season progresses to match within-season changes in predation pressure in different types of territories.     

Breeding phenology and winter activity predict subsequent breeding success in a trans-global migratory seabird

Inter-seasonal events are believed to connect and affect reproductive performance (RP) in animals. However, much remains unknown about such carry-over effects (COEs), in particular how behaviour patterns during highly mobile life-history stages, such as migration, affect RP. To address this question, we measured at-sea behaviour in a long-lived migratory seabird, the Manx shearwater (Puffinus puffinus) and obtained data for individual migration cycles over 5 years, by tracking with geolocator/immersion loggers, along with 6 years of RP data. We found that individual breeding and non-breeding phenology correlated with subsequent RP, with birds hyperactive during winter more likely to fail to reproduce. Furthermore, parental investment during one year influenced breeding success during the next, a COE reflecting the trade-off between current and future RP. Our results suggest that different life-history stages interact to influence RP in the next breeding season, so that behaviour patterns during winter may be important determinants of variation in subsequent fitness among individuals.     

Breeding group size, nest position and breeding success in the chinstrap penguin

We studied the effect of breeding group size and nest position on breeding success in the chinstrap penguin (Pygoscelis antarctica). Large subcolonies sited at Vapour Col, Deception Island, had higher breeding success than small subcolonies, which suffered a higher chick mortality than large subcolonies. Hatching date was earlier in large colonies. Relationships were not found between mean hatching date per subcolony and mean chick survival. Chick mortality related to nest position showed no difference between central and peripheral nests in large subcolonies. Central nests hatched earlier than peripheral nests. Nests in large subcolonies, whatever their position, were more successful compared with nests in small subcolonies. Received: 16 April 1997 / Accepted: 12 July 1997     

Age and breeding success of a Golden Eagle Aquila chrysaetos population in southeastern Spain

Brood production rate of Grey Partridges Perdix perdix was studied in three areas in Poland in the years 1986–90, by comparing the number of pairs and the number of family coveys after the breeding period. In the study areas, linear permanent nesting cover was mapped and measured. In these areas the brood production rate declined with increasing spring pair density. A positive effect of the occurrence of nesting cover on brood production rate was found. An increase in the population density mostly occurred through occupying parts of the study area avoided earlier, thus presumably less suitable for Partridges. Pairs occupying these less suitable areas, characterized by less abundant nesting cover, had a lower brood production rate, whereas in the preferred areas this rate did not decline with increasing mean population density.     

Nest site, laying period, and breeding success of the Woodchat Shrike (Lanius senator) in Mediterranean France

Summary Breeding habitats in Mediterranean France consist in open, dry grasslands with a low and discontinuous grass layer and scattered bushes and trees. The choice of nest supports was largely opportunistic, the most abundant suitable nest support type (bush or tree) and the most abundant species being present at each study site have been used. About 75% of the nests were placed at heights between 1 and 3 m. Laying period lasted from 9 May until 6 July (peak of first clutches: 21–30 May). Mean clutch size was 5.14±0.82 eggs (n=114). Breeding success was independent from the site, the height and the concealment of nests. Mean survival rate of nests from laying to fledgling was 0.365. The main cause of low breeding success was high nest predation exerted by a rich guild of predators. The species is mainly threatened through dramatic habitat shrinkage due to pastoralism reduction leading to closures of lightly bushed grasslands in Mediterranean France.

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Nistplatzwahl, Legeperiode und Bruterfolg des Rotkopfwürgers (Lanius senator) in Südfrankreich

Zusammenfassung Als Bruthabitat bevorzugt der Rotkopfwürgers im mediterranen Südfrankreich offene und trockene Graslandlandschaften mit niedrigem oder lückigem Grasbewuchs und einzelstehenden Büschen und/oder Bäumen. Häufigster Nestträger ist die jeweils im Brutterritorium häufigste Baum- oder Buschart. Ungefähr 75% der Nester standen zwischen 1 und 3 m über Boden. Die Legeperiode reichte vom 9. Mai bis 6. Juli (Gipfel der Erstgelege am 21.–30. Mai und der Ersatzgelege am 20.–24. Juni). Die Gelegegröße bestand aus 3 bis 7, meist 5 Eier (Erstgelege im Mittel 5,35±0,71 Eier, Ersatzgelege: 4,68±0,85). Der Bruterfolg war unabhängig von der Lage, der Höhe und der Verborgenheit des Nestes. Die mittlere Überlebensrate eines Nestes zwischen Bebrütung des Geleges und Ausfliegen der Jungen betrug 0,365. Dieser niedrige Bruterfolg wurde hauptsächlich durch Nesträuber verursacht. In Südfrankreich ist die Art aber vor allem durch die zunehmende Verschließung der Bruthabitate infolge des Rückgangs des extensiven Weidebetriebs gefährdet.

     

Breeding biology during establishment of a reintroduced Griffon Vulture Gyps fulvus population

We studied the breeding parameters of a reintroduced population of individually marked Griffon Vultures Gyps fulvus in the Grand Causses region of southern France from the time of first reintroduction in 1982 to 1992. Among nesters, 65% of the birds released as immatures or born in the wild recruited into the breeding population when 4 years old, i.e. 1 year earlier than previously described. The proportion of birds nesting each year was relatively high and increased with time, suggesting that conspecific attraction favoured recruitment. We detected a permanent adverse effect of long-term captivity on the nesting success of birds released when more than 2 years old: compared to the natural population, birds which had been kept in captivity showed a reduced breeding success during the whole study period. The breeding success of released immatures and wild-born birds was similar to the highest values observed in a natural population in the Spanish and French Pyrenees. Breeding failures did not usually result in mate change but affected nest-site fidelity. Birds not born in the wild were more likely to recruit to the largest subcolonies available, which highlights the role of social attraction. The observed philopatry of wild-born birds probably resulted from such a social attraction since most of them were born in the largest subcolony. Conspecific attraction maintained the spatial aggregation of nests, whereas nest changes after a breeding failure favoured the spatial expansion of the colony.