Breeding ecology of a suburban population of Woodpigeons Columba palumbus in northwest England

Capsule Between 1981 and 2008 population size was stable, but there were negative trends in breeding parameters.

Aims To determine the current status and long‐term population trend of an isolated breeding population of Bearded Vultures Gypaetus barbatus (Corsica, Mediterranean).

Methods The total Bearded Vulture population was monitored between 1981 and 2008.

Results The current effective breeding population size of Bearded Vultures in Corsica is ten pairs/trios with a slight increase of one to two pairs since 1983. The population is currently estimated at 25 individuals. Breeding parameters (laying rate, breeding success and productivity) have decreased significantly over the full 28‐year study period, although the decrease was not significant when the data set was restricted to 1988–2008. A mean of 60.3% (n = 204) of pairs have laid, but this proportion is highly variable between years. Productivity has been very low (0.16 young/pair/year, n = 233). Breeding parameters of the Corsican population of Bearded Vultures are very low compared with those of other western European populations in the Pyrenees.

Conclusions This isolated insular population is of small size (eight to ten pairs/trios) but shows a stability of distribution and numbers, but low (and decreasing) breeding rates, making this insular population one the most threatened in Europe.     

Breeding status of the Red Kite Milvus milvus in Britain in 2000

Capsule The first co-ordinated Red Kite survey across Britain since the reintroduction programme began in 1989, yields 430 breeding pairs.

Aims To estimate the current size and extent of the British breeding population.

Methods A complete census of the populations in the East Midlands, Yorkshire, central and north Scotland was undertaken, while in Wales and the Chilterns, populations were surveyed using a stratified sample of tetrads. Breeding and territorial pairs were identified.

Results The survey indicated that there were 430 breeding pairs in Britain (95% CIs, 372–490). There were 259 breeding pairs in Wales (95% CIs, 200–318) and 109 (95% CIs, 96–124) in the Chilterns. Elsewhere, 16 breeding pairs were located in the East Midlands, three in Yorkshire, seven in central Scotland and 33 in north Scotland. An additional three pairs were recorded in southern England, away from the main population centres.

Conclusion The 2000 survey provides a baseline against which to measure future changes in Red Kite populations in Britain, using standard, repeatable methods.     

The social organization and breeding behaviour of the Yellow-faced Honeyeater Lichenostomus chrysops– a migratory passerine from the Southern Hemisphere

Southern Hemisphere passerines are generally thought to have long breeding seasons and high annual survivorship, but this may reflect a bias resulting from a disproportionate concentration on sedentary species. This study presents a detailed examination of the breeding biology and social organization of a migratory population of a passerine from the Southern Hemisphere – the Yellow‐faced Honeyeater Lichenostomus chrysops. It took place between 1997 and 2000 in the Coranderrk Reserve, Healesville, Australia. Following the birds’ return from migration, breeding commenced in mid‐November, roughly 2 months after arrival. The breeding season was short (3.5–4 months) compared with sedentary honeyeaters occupying the same habitat. Territories (0.19 ± 0.11 ha) were established by males but defended by both sexes against conspecific and heterospecific intruders. Within a breeding season, pairs were multibrooded (mean no. of clutches per season 2.14 ± 0.76, range 1–3) and always re‐nested within the same territory with the same partner. However, only 12.5% of pairs bred together in a subsequent breeding season despite, on many occasions, their partner from the previous season being alive (divorce rate of 75% for males and 66% for females). Females alone built the nest, incubated the eggs and brooded the nestlings. However, males contributed 44.5% of feeding visits to nestlings. The breeding cycle of Yellow‐faced Honeyeaters (clutch size 1–3 eggs, mean 2.4 ± 0.6, n = 84, incubation period 14.4 ± 0.7 days, n = 11, nestling period 13.0 ± 1.7 days, n = 6) was similar to that of sedentary honeyeaters (and Southern Hemisphere Corvidae in general), except that fledglings only remained on the parental territory for 2–3 weeks post‐fledging. At least one young fledged from 32.1% of nests (n = 156). Predation was the major cause of nest failure (74.5% of 106 failed nests). Only 4.4% of nestlings (n = 136) were observed on the study site in subsequent seasons (five males and one female). None of those males was observed on the study site until their second year of life. Adult annual survivorship (ignoring losses due to dispersal) was 43% for females and 51% for males. Our study suggests that if more data were available for the numerous migratory species from the Southern Hemisphere, some apparent differences from northern hemisphere passerines might disappear.     

Wind turbine fatalities approach a level of concern in a raptor population

Mortality from collisions with increasing numbers of wind turbines is a potential hazard to raptor populations, but the actual effects on a population scale have rarely been studied based on field data. We estimated annual collision numbers for Red Kites Milvus milvus in the German federal state of Brandenburg (29,483 km²). A hierarchical model considering carcass persistence rate, searcher efficiency and the probability that a killed animal falls into a searched area was applied to results of carcass searches at 617 turbines. Collision risk varied significantly with season. The model estimated 308 (95% CrI 159–488) Red Kite fatalities at 3044 turbines operating during 2012, representing 3.1% of the estimated post-breeding population of 9972 individuals. Using the potential biological removal (PBR) method, mortality thresholds of 4.0% were obtained for migratory Red Kite populations. This level of mortality may be reached when turbine numbers increase within a few years. Since wind turbine collisions may affect Red Kites throughout the global range, a more detailed assessment of the actual impacts on populations is needed, especially because the PBR does not account for the predominance of adult birds among the collision victims.     

Successful breeding at one year of age by Red Kites Milvus milvus in southern England

This paper presents the first data on individually tagged male and female Red Kites Milvus milvus breeding at 1 year old and is validated by genetic fingerprinting. The data were collected during 1989 to 1994 when Red Kite nestlings were translocated to, and released in, southern England as part of a re-establishment project. A total of 23 1-year-old Red Kites attempted to breed in southern England from 1991 to 1994, of which three pairs, each composed of at least one yearling bird, reared five young. We conclude that habitat quality is ultimately the main influence that determines whether Red Kites can breed and how well they breed. However, individual experience, climate and competition with other Red Kites for nesting territories probably influence the age at which an individual can breed in a particular habitat.     

The diet of migrant Red Kites Milvus milvus during a Water Vole Arvicola terrestris outbreak in eastern France and the associated risk of secondary poisoning by the rodenticide bromadiolone

Poisoning by pesticides is considered one of the primary threats to the Red Kite Milvus milvus. We studied the diet of this raptor in an area of eastern France where the rodenticide bromadiolone is widely used to control Water Vole Arvicola terrestris outbreaks. A high degree of specialization for Water Voles was noted, as their remains were identified in all 119 pellets collected in autumn 2008, whereas other small rodent species and insects occurred in 27 and 9% of pellets, respectively. We estimated that Water Voles constituted 94% of the total biomass ingested by Red Kites under these conditions. Based on these data, the risk of secondary poisoning due to feeding on poisoned voles was assessed. Acute exposure on a single day was not considered a risk for Kites, but exposure to poisoned voles over 1 week represented the maximal risk for the Red Kite; the calculated dose of bromadiolone ingested by a Red Kite was 137 times higher than the toxicological benchmark for birds. A field survey in the studied area detected four dead Red Kites and one moribund bird in autumn 2008 but did not confirm that the cause of death was bromadiolone poisoning. We suggest that professional monitoring is needed to assess the impact of rodenticides on Red Kites in areas where voles are controlled.     

Widespread supplementary feeding in domestic gardens explains the return of reintroduced Red Kites Milvus milvus to an urban area

Reintroductions are commonly used to mitigate biodiversity loss. One prominent example is that of the Red Kite Milvus milvus, a charismatic raptor of conservation concern. This species has been reintroduced across the UK over the last 25 years following its near extinction after centuries of persecution. The species was not expected to recolonize urban areas; its historical association with human settlements is attributed to scavenging on human waste and refuse, a resource now greatly reduced on the streets of modern European cities. However, the species has become a common daytime visitor to a large conurbation centred on the town of Reading, southern England, approximately 20 km from the first English reintroduction site. Given a near‐absence of breeding and roost sites, we investigated foraging opportunities and habitat associations that might explain use by Red Kites of this urban area. Surveys of discarded human foods and road‐kill suggested that these could support at most 13–29 Kites per day. Face‐to‐face surveys of a cross‐section of residents revealed that 4.5% (equivalent to 4349 households) provided supplementary food for Red Kites in their gardens. Using estimates of per‐household resource provision from another study, we calculated that this is potentially sufficient to feed 142–320 Kites, a substantial proportion of the total estimated to visit the conurbation each day (between 140 and 440). Road transects found positive associations between Red Kites and residential areas. We suggest that the decision made by thousands of householders to provide supplementary food for Red Kites in their gardens is the primary factor explaining their daytime abundance in this urban area.     

Nest survival and productivity of the critically endangered Sociable Lapwing Vanellus gregarius

The Sociable Lapwing Vanellus gregarius is a critically endangered species, probably declining from 5000 pairs to 500 pairs in 11 years. Fieldwork was conducted at two sites in Kazakhstan, May–August 2004, to identify causes of the species’ decline. In total, 58 nests and a minimum of 36 broods in 16 colonies were found: colonies consisted of 1–8 nests that were on average 154 m apart, with 2.1 km between colonies. Although classified as biparental, the total proportion of time both parents spent incubating was low (77 ± 2% se, n = 13 nests). Daily survival rates (Mayfield method) were very low during incubation (0.943 ± 0.009 se) but high during the chick stage (0.986 ± 0.004 se); incubation and chick‐stage durations were found to be 28.5 and 29 days, respectively, so that the overall probability of any breeding attempt fledging chicks was 0.124 (0.055–0.274 95% confidence interval). A breeding attempt that produced fledglings, fledged 2.2 ± 0.2 se chicks (n = 26) on average. Observed productivity predicted the population decline over the last 11 years well (using the maximum number of nesting attempts per pair of 1.4 that could have occurred in this study, and assuming an adult and first‐year survival rate of 0.74 and 0.60, respectively, based on the means for Northern Lapwing Vanellus vanellus and Golden Plover Pluvialis apricalia). Nest survival during incubation (controlling for colony effects) may have been longer for nests in predominantly Artemisia rather than grass habitat. Mean nest survival for a colony was higher in areas with more bare ground and more nest predators, suggesting that predators were relatively unimportant in nest (egg or chick) mortality, but was lower in areas with high numbers of cattle, suggesting that trampling was important (64% of known‐cause nest failures, n = 11, were trampled). Nests were preferentially sited in areas of Artemisia, where there was greater dung abundance, and probably shorter vegetation, suggesting that highly grazed vegetation is important for nesting. Chicks preferentially selected areas with a lower percentage of bare ground and possibly taller vegetation, suggesting that more vegetated areas are important for chicks. The results suggest that low egg survival due to nesting in areas of high grazer density may be responsible for the Sociable Lapwing's decline. Although grazers may create suitable vegetation for initial nesting, if those grazers remain at high density as in anthropogenic systems then they may reduce nest survival, probably through trampling. Experimentally maintaining grazing early but reducing it later in the breeding season is the logical first step in managing the species to increase egg survival and so to increase productivity.     

Brutbiotop und Territorialit?t bei Habicht (Accipiter gentilis) und Rotmilan (Milvus milvus)

Zusammenfassung In einem Gebiet auf der Schwäbischen Alb von 432 km² mit weitgehend homogener Waldverteilung brüteten 13 Habicht- und 20 Rotmilanpaare. Die Horsthöhe über dem Boden lag bei beiden Arten oberhalb der Handbuchangaben. Eine Bevorzugung von Laubwaldhabitaten durch den Rotmilan war nicht erkennbar. Die regelmäßige intraspezifische Dispersion der Horstreviere beider Arten läßt auf das Vorhandensein intraspezifischer Territorialität schließen. Eine Regelmäßigkeit in der interspezifischen Dispersion war hingegen nicht erkennbar. Negative Einflüsse des Habichts auf den Reproduktionserfolg des Rotmilans waren ebenfalls nicht nachweisbar. Konkurrenz um Horstplätze zwischen Habicht und Rotmilan spielte im untersuchten Gebiet somit eine unbedeutende Rolle. Die Wirkung solcher Konkurrenz als ein für konstante Populationen allgemeingültiger Regulationsmechanismus nachKostrzewa et al. (1985) wird in Frage gestellt. Allein im Abstand des Horstes zum Waldrand bestand im Untersuchungsgebiet eine klare Trennung der Horstplatzansprüche beider Arten.

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Nesting habitat and territoriality in Goshawk (Accipiter gentilis) and Red Kite (Milvus milvus)

Summary Intraspecific and interspecific spacing of Goshawk and Red Kite nesting places were investigated in an area of 432 km² located in southern Germany. The area is characterized by a relatively homogeneous forest distribution. Nesting habitat data were collected over a period of four years. Thirteen breeding pairs of Goshawk und twenty breeding pairs of Red Kite were censused within the study area. The mean heights of nests above ground in both species were greater than those previously described (i. e.Cramp &Simmons 1980). The current view, that Red Kites prefer deciduous forest nesting habitats and deciduous nest trees, could not be confirmed.The regular intraspecific spacing of nesting places in both species indicates intraspecific territoriality. In contrast, no regularity in interspecific spacing could be detected. There was no noticeable influence of the Goshawk on the reproduction success of the Red Kite. Thus, competition for nesting places in the investigated area among Goshawk and Red Kite plays, if any, only a minor role. A factor seperating the two species with high significance is the distance from the nesting place to the nearest forest edge.In conclusion, the present study shows that competition for nesting places as a regulation mechanism, as proposed byKostrzewa et al. (1985), is unlikely.

     

Family break-up in Black and Red Kites Milvus migrans and M. milvus: is time of independence an offspring decision?

I observed the natural process of family break-up in 13 families of Black Kites Milvus migrans and five families of Red Kites M. milvus in which fledglings had been individually marked. In other broods, I performed experiments which modified the parental investment fledglings received by supplementing nests of both species with food or transferring Black Kite chicks to nests with younger or older chicks of the same species.
The time of family break-up in the Black Kite is mainly an offspring decision which is not affected by an artificial increase of parental investment. The duration of the post-fledging period was not increased in Black Kites that were given supplementary food. Chicks transferred to nests with a younger chick did not extend the post-fledging period, nor did chicks transferred to nests with an older chick shorten the post-fledging period. In Red Kites, parental investment seemed to have more influence on the timing of the family break-up. Red Kite adults invested less as parents than did Black Kites during the post-fledging dependence period, and in nests where supplementary food was given, Red Kite fledglings stayed attached for a longer period.     

Difference in age,growth, and sexual demography of black‐spot tuskfish,Choerodon schoenleinii (Valenciennes, 1839), in two adjacent populations,Ryukyu Archipelago,southern Japan

To better understand the plasticity of life history traits in the blackspot tuskfish, Choerodon schoenleinii (Valenciennes, 1839), the characteristics of the population around the Yaeyama Islands (24°N, 124E) were examined and compared to those around Okinawajima Island (26°N, 128E) that had been investigated in a previous study. Age and growth of the Yaeyama population were examined based on 103 specimens collected at fish markets between 2006 and 2016. Specimens included 83 females (25.2–69.0 cm total length [TL]), and 20 males (43.1–71.8 cm TL). Ages determined from sectioned otoliths ranged from 1–9 for females, and 4–15 for males. Values for von Bertalanffy growth functions were L_t = 74.2 {1?exp[?0.23 (t + 0.38)]}, and the growth of the Yaeyama population was significantly faster than that of the previously studied population. Sexual demography of the two populations was compared using body length data on landings measured at the fish markets. In the Yaeyama population, females and males ranged from 24–65 cm TL and 39–75 cm TL, respectively; length at 50% individual sex change size was estimated at 54.7 ± 0.56 cm (±95% C.I.). In contrast, in the Okinawajima population, females and males ranged from 16–65 cm TL and 30–75 cm TL, respectively; meanwhile, 50% sex change size was estimated to be 50.0 ± 0.25 cm. There were thus significant differences in the size at sex change between the two populations. This difference may be related to the difference in population density between the sites.     

Zur Situation der MilaneMilvus milvus fasciicauda (Hartert, 1914) undMilvus m. migrans (Boddaert, 1783) auf den Kapverdischen Inseln

Zusammenfassung WährendMilvus milvus fasciicauda undMilvus m. migrans in den 1950er Jahren noch sympatrisch auf fast allen Inseln anzutreffen waren, umfaßt der Bestand heute, nach der Erfassung in den Jahren 1996 und 1997, lediglich zehn Individuen pro Art auf je einer Insel. Diese drastische Abnahme ist unter anderem auf Landschaftsveränderungen, Vergiftungen und Verfolgung durch den Menschen zurückzuführen.

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Status of the KitesMilvus milvus fasciicauda (Hartert, 1914) andMilvus m. migrans (Boddaert, 1783) on the Cape Verde Islands

Summary In 1996 and 1997 population size ofMilvus milvus fasciicauda andMilvus m. migrans was censused and estimated to be five to six individuals for the former and three to five for the latter. In the 1950's,Milvus m. migrans and the endemicMilvus milvus fasciicauda were sympatric taxa on most of the Cape Verde Islands. While still widely distributed in the 1980's, the Black Kite today is restricted to Boavista, the eastermost island. The Red Kite less widely distributed in the 1950's and in the 1980's restricted to three islands, is now found only on Santo Antao, the westernmost island. There is no evidence of breeding of either of the two Kites.This drastic reduction of Kites on the Cape Verde Islands may be due to habitat changes associated with the expansion of the Sahel region resulting in an increase in aridity on the islands, the pressure from human activities in the form of new settlements, structural changes in agriculture like overgrazing by goats, as well as the use of poisened meat as a bait, the use of rodentizides, and persecution.

     

Morphological adaptation of an invasive American mink population in Mediterranean areas of Spain

In this work we studied the morphology of an invasive population of American mink Mustela vison in Catalonia, Mediterranean Spain. Body weight, body length, tail length, hindfoot length and ear length were measured for four age–sex classes: subadult male (n = 17), subadult female (n = 16), adult male (n = 36) and adult female (n = 10). A General Linear Mixed Model was used to test the effect of year, sex, age and age–sex interaction, on each parameter. The morphological results differed from those of other introduced populations because of their different origin and their adaptation to different environments. Differences in sex and age were found, pointing to sexual dimorphism both in adults and subadults. The degree of dimorphism was lower than that of other populations, probably because of a lack of trophic niche separation between male and female mink because in the study area only small prey animals were available.     

Breeding biology of Montagu’s Harrier Circus pygargus in north-central Kazakhstan

The ecology and conservation status of Central Asian populations of Montagu’s Harriers Circus pygargus are poorly known. We studied the breeding biology of this species during 3 years in the Naurzum region, north-central Kazakhstan. Most Montagu’s Harriers in the study area nested in the forest-steppe transition area, in bushy areas dominated by dogrose Rosa canina, which was apparently the nesting vegetation type providing highest and densest nest cover in the study area. Laying occurred from 26 April to 7 June (average 13 May, n = 49) and, although it varied significantly between years, was earlier than in western European populations of similar latitude. Mean (±SD) clutch size was 4.44 ± 0.86 (range 2–6; n = 50), in the higher range observed for the species. There was no significant interannual variation in clutch size, despite large variations in the abundance of small mammals in the area. Diet was mainly composed of lizards (54.2%, n = 533 identified prey in all 3 years), with small mammals (17.1%), passerine birds (14.3%) and insects (13.6%) also being consumed. Mean brood size at the last visit was 2.55 ± 2.10 (range 0–6; n = 51). Failure rate was relatively high; the main identified cause of nest failure was predation. We compare the data obtained in this population breeding in natural steppes with breeding parameters from the well-studied western European populations, and discuss the implications for the conservation of this species.     

Isolation and characterization of polymorphic tetranucleotide microsatellite loci in the chestnut-crowned babbler (Pomatostomus ruficeps)

We describe 18 microsatellite markers isolated in the cooperatively breeding chestnut‐crowned babbler (Pomatostomus ruficeps). The number of alleles ranged from seven to 16 per locus (mean N_a = 10.4 ± 0.54 SE) and the expected heterozygosity ranged from 0.732 to 0.889 (mean H_E = 0.836 ± 0.01 SE). Three of the 18 loci exhibited significant heterozygote deficiency, but the remaining 15 will be used to analyse population genetic structure and the mating system of this highly social species.     

Demographic Consequences of Poison-Related Mortality in a Threatened Bird of Prey

Evidence for decline or threat of wild populations typically comes from multiple sources and methods that allow optimal integration of the available information, representing a major advance in planning management actions. We used integrated population modelling and perturbation analyses to assess the demographic consequences of the illegal use of poison for an insular population of Red Kites, Milvus milvus. We first pooled into a single statistical framework the annual census of breeding pairs, the available individual-based data, the average productivity and the number of birds admitted annually to the local rehabilitation centre. By combining these four types of information we were able to increase estimate precision and to obtain an estimate of the proportion of breeding adults, an important parameter that was not directly measured in the field and that is often difficult to assess. Subsequently, we used perturbation analyses to measure the expected change in the population growth rate due to a change in poison-related mortality. We found that poison accounted for 0.43 to 0.76 of the total mortality, for yearlings and older birds, respectively. Results from the deterministic population model indicated that this mortality suppressed the population growth rate by 20%. Despite this, the population was estimated to increase, albeit slowly. This positive trend was likely maintained by a very high productivity (1.83 fledglings per breeding pair) possibly promoted by supplementary feeding, a situation which is likely to be common to many large obligate or facultative European scavengers. Under this hypothetical scenario of double societal costs (poisoning of a threatened species and feeding programs), increasing poison control would help to lower the public cost of maintaining supplementary feeding stations.     

Distribution, density, diet and productivity of the Scops Owl Otus scops in the Italian Alps

The Scops Owl Otus scops is probably the least known European owl. We surveyed Scops Owls in the Trento region (6200 km²) of the central–eastern Italian Alps between 1995 and 2003 and we intensively monitored a subpopulation in a 50‐km² plot between 2000 and 2003. In the whole region, we found 81 territories concentrated in 21, low‐elevation 100‐km² quadrats. Most territories were associated with villages surrounded by extensively managed grassland (79%), arid areas with rocky outcrops and xerophytic vegetation (12%) and/or large urban areas and parks (6%). In the 50‐km² plot, density varied between 52 and 64 territories/100 km² annually. Territories were either solitary or clumped in loose colonies of 2–7 pairs. In contrast to previous studies, most nests used for laying were in holes and cracks of buildings (95%, n = 20). This may have been favoured by thermal and foraging advantages, but also involved some costs, such as predation by domestic cats and collision with cars. Median laying date was 29 May (n = 16) and the mean number of fledged young was 1.37 (n = 30), 1.95 (n = 21) and 2.00 (n = 20) per territorial, breeding and successful pair, respectively. The diet was dominated by grasshoppers of the family Tettigoniidae. Compared to previous studies, this population showed medium to high density and low productivity. The species seems to be dependent on traditional, extensive agro‐pastoralism and the main conservation threats include habitat loss through land abandonment and consequent forest expansion, which are probably best halted through subsidy schemes. From our results and published data, we estimate the population of the Scops Owl in the Italian Alps at 230–500 territories. There is an urgent need for further data on this largely overlooked species, especially from its Mediterranean strongholds.     

The effect of changes in habitat conditions on the movement of juvenile Snail Kites Rostrhamus sociabilis

The degradation of habitats due to human activities is a major topic of interest for the conservation and management of wild populations. There is growing evidence that the Florida Everglades ecosystem continues to suffer from habitat degradation. After a period of recovery in the 1990s, the Snail Kite Rostrhamus sociabilis population suffered a substantial decline in 2001 and has not recovered since. Habitat degradation has been suggested as one of the primary reasons for this lack of recovery. As a consequence of the continued degradation of the Everglades, we hypothesized that this would have led to increased movement of juvenile Kites over time, as a consequence of the need to find more favourable habitat. We used multistate mark‐recapture models to compare between‐site movement probabilities of juvenile Snail Kites in the 1990s (1992–95; which corresponds to the period before the decline) and 2000s (2003–06; after the decline). Our analyses were based on an extensive radiotelemetry study (266 birds tracked monthly over the entire state of Florida for a total period of 6 years) and considered factors such as sex and age of marked individuals. There was evidence of increased movement of juvenile Snail Kites during the post‐decline period from most of the wetland regions used historically by Kites. Higher movement rates may contribute to an increase in the probability of mortality of young individuals and could contribute to the observed declines.     

Differences in the onset of laying between island and mainland Mediterranean Blue Tits Parus caeruleus: phenotypic plasticity or genetic differences?

Blue tits Parus caeruleus breeding in deciduous or in evergreen woodlands on the mainland of Europe start to lay 3–4 weeks earlier than Blue Tits on the island of Corsica breeding in evergreen woodlands. A similar difference in average laying date between the two Blue Tit populations has been found in a relatively small sample of captive birds held in outdoor aviaries on the mainland. To provide data on the habitat contrast in Corsica for comparison with that on the mainland, a new study area was started in one of the few deciduous woodlands on Corsica. In addition, new data on laying dates of captive Blue Tits were gathered to increase the sample size of independent pairs in aviaries. This study shows that the habitat effect (deciduous ν evergreen woodland) on the average laying date of Blue Tits is relatively small in comparison with the geography effect (European mainland ν Corsica). The laying date differences between mainland and insular Blue Tits persisted whatever the type of habitat (deciduous, evergreen or outdoor aviaries on the mainland). The data support the hypothesis that the observed differences in the onset of laying between the mainland and insular Blue Tits were mainly influenced by genetic effects and relatively little by non-genetic maternal effects of by genotype—environment interactions.