Lesser Kestrel Falco Naumanni Research Articles

Home range and foraging habitat selection by breeding lesser kestrels (Falco naumanni) in Greece

Home range size and foraging habitat use in breeding lesser kestrels (Falco naumanni), a bird species of conservation concern, were investigated during the breeding season of the species in 2008 in an intensively cultivated area of central Greece, using radio-tracking. Grasshopper (the main prey) densities were measured at the most important habitats (cotton, cereals, grasslands and margins). Home ranges were not significantly different between sexes either as overall means or during incubation and nestling periods. Movements of both sexes were non-random during incubation but random during the nestling period. Habitats used by males during incubation ranked as: margins > other > cotton > corn > cereals and during nestling period as: cereals > margins > grasslands > corn > cotton. Female habitat use greatly differed ranking as cereals > cotton > grasslands during incubation and as grassland > cotton > corn > cereals > margins during nestling period. Female habitat use seemed to be in disagreement with the conditions generally favouring prey availability, probably for reasons associated with low and uniform distribution of grasshopper densities over the habitats.

Food for flight: pre-migratory dynamics of the Lesser Kestrel Falco naumanni

Capsule The post-reproductive stage of Lesser Kestrel is crucial for migratory fuelling and survival.Aims To describe the summer pre-migratory ecology of the Lesser Kestrel in Sicily and review existing data in Southern Europe.Methods We identified the main summer roosts and then made roost counts every ten days from 2010 to 2012. We used case-sensitive modelling procedures to detect biases in counts (generalized linear mixed models), assess the annual population trends from 2005 to 2012 (TRends and Indices for Monitoring); and to model habitat preferences (generalized linear model). We sampled pellets to describe the birds’ diet during the peak month prior to migration.Results We discovered five roosts in Sicily with numbers of Lesser Kestrels varying annually (mean ± sd: 2112 ± 387; min–max: 1797–2544). Counts at the main roost were not biased by meteorological conditions and showed an August peak followed by persistent decline through October. Less urbanized and heterogeneous agricultural areas with large cereal fields were the most significant habitats preferred during summer. Within this landscape, Lesser Kestrels prey on seasonally high concentrations of the small cricket Grylloderes brunneri.Conclusion Arable land not fragmented by agricultural intensification supports habitat rich with Orthopterans and attracts a large number of Lesser Kestrels fuelling before migration. Conservation of such pre-migratory habitats is as vital as conservation of breeding areas.

Evidence of increasing Lesser Kestrel Falco naumanni populations in Morocco (North Africa): a confirmation of ‘Least Concern’ conservation status

Capsule The number of Lesser Kestrel Falco naumanni breeding pairs in Morocco has varied significantly and positively over thirteen years (1998–2010), between six colonies and over the 13-year period at each colony. The mean growth rate was λ = 1.13 ± 0.02. This positive trend is consistent with the current Least Concern conservation status of the species in the IUCN Red List.

Nest aggregation and reproductive synchrony promote Lesser Kestrel Falco naumanni seasonal fitness

Several factors promote coloniality by enhancing the fitness of colony members. In birds, spatial proximity among nests, breeder abundance and reproductive synchrony have been proposed as primary factors responsible for enhanced colonial defence and foraging success, which, in turn, enhance reproductive success. Whether these factors function synergistically or antagonistically remains, however, an open question due to the absence of an integrated analysis of their effects on fitness. We studied a large population of the Lesser Kestrel, Falco naumanni, a facultative colonial species, breeding in colonies of different sizes in their typical pseudo-steppe habitat. We quantified both the singular and interactive effects of nest distance, breeder abundance and reproductive synchrony on kestrel fitness measured as the time to survival of eggs to hatching and nestlings to fledging. Egg survival increased as reproductive stages became more synchronous with the timing of colony breeding, whereas nestling survival benefited from a higher synchrony with most nests in the entire population. Nestling survival was also positively affected by the interaction between nest distance and breeder abundance. Our results suggest that the presence of additional breeders in the colony is not sufficient per se, to trigger colonial advantages, but instead, that synchronised reproduction among multiple breeding pairs nesting in close spatial proximity is necessary to realise those benefits. Our findings provide a novel perspective for future investigations that explore the mechanisms underlying fitness variation among Lesser Kestrel colonies and group-living species in general.

Crop vegetation structure is more important than crop type in determining where Lesser Kestrels forage

SummaryWe studied foraging habitat selection by Lesser Kestrel Falco naumanni throughout the breeding period in south-west Spain by means of transects on which foraging observations were recorded. We focused on the effects of habitat and crop type, but also on the effect of vegetation structure and the presence of agricultural activities in the field on Lesser Kestrel use. We considered both the accumulated use of the foraging area during the breeding season and the instantaneous foraging habitat selection by kestrels. Foraging habitat selection was highly dynamic following crop development and agricultural activities. Almost all major arable crop types showed positive selection during some part of the breeding cycle. Accumulated use by kestrels demonstrated positive associations with wheat and cotton fields and negative selection of permanent habitat types, such as forested areas, woody crops and built-up areas that have no prey or are not used by the species due to unfavourable structure. Vegetation structure appears to play a major role in instantaneous foraging selection. Lesser Kestrels select fields with short vegetation and intermediate cover. They also forage on field margins and where agricultural activities such as ploughing or harvesting that facilitate access to prey are being conducted. Our results help to clarify apparent controversies among previous studies on the subject, highlighting the importance of the heterogeneity of agricultural landscapes around colonies (crops at different growth stages which provide variable vegetation height and cover during the breeding cycle) and the effect that agricultural activities have on facilitating access to prey. Beyond the species-specific approach, our work encourages further studies on habitat selection by farmland birds to account not only for human-based categorisation of habitats (e.g. crop type) but also on objective measures such as vegetation height and cover that influence access to prey and better reflect the high dynamism of agricultural landscapes.

Foraging Habitat Quality Constrains Effectiveness of Artificial Nest-Site Provisioning in Reversing Population Declines in a Colonial Cavity Nester

Among birds, breeding numbers are mainly limited by two resources of major importance: food supply and nest-site availability. Here, we investigated how differences in land-use and nest-site availability affected the foraging behaviour, breeding success and population trends of the colonial cavity-dependent lesser kestrel Falco naumanni inhabiting two protected areas. Both areas were provided with artificial nests to increase nest-site availability. The first area is a pseudo-steppe characterized by traditional extensive cereal cultivation, whereas the second area is a previous agricultural zone now abandoned or replaced by forested areas. In both areas, lesser kestrels selected extensive agricultural habitats, such as fallows and cereal fields, and avoided scrubland and forests. In the second area, tracked birds from one colony travelled significantly farther distances (6.2 km ±1.7 vs. 1.8 km ±0.4 and 1.9 km ±0.6) and had significant larger foraging-ranges (144 km2 vs. 18.8 and 14.8 km2) when compared to the birds of two colonies in the extensive agricultural area. Longer foraging trips were reflected in lower chick feeding rates, lower fledging success and reduced chick fitness. Availability and occupation of artificial nests was high in both areas but population followed opposite trends, with a positive increment recorded exclusively in the first area with a large proportion of agricultural areas. Progressive habitat loss around the studied colony in the second area (suitable habitat decreased from 32% in 1990 to only 7% in 2002) is likely the main driver of the recorded population decline and suggests that the effectiveness of bird species conservation based on nest-site provisioning is highly constrained by habitat quality in the surrounding areas. Therefore, the conservation of cavity-dependent species may be enhanced firstly by finding the best areas of remaining habitat and secondly by increasing the carrying capacity of high-quality habitat areas through safe nest-site provisioning.

Changes in eggshell ultrastructure of Falco naumanni and Tyto alba exposed to pesticides and polychlorinated biphenyls (PCBs)

Changes in the quality of eggs of birds exposed to environmental contaminants have been described, but few reports concern eggshell ultrastructure. In this study, infertile or addled Lesser Kestrels (Falco naumanni) and Barn owls (Tyto alba) eggs were collected from the polluted area of Gela plain (Sicily) during 2007, and compared in terms of organophosphate and organochlorine pesticides, and PCBs levels, and eggshell ultrastructure as determined by scanning electron microscopy. Pesticide and PCB residues in eggs were determined by Gas chromatography/ mass spectrometry (GC/MS) [GC Agilent 7890A/MS Agilent 5975C (Agilent technologies) using a DB-5 capillary column in the selected ion monitoring mode]. The GC/MS analysis revealed that eggs contained measurable amounts of some pesticides and PCBs. There was a low detection of organophosphate pesticides while the most abundant organochlorine residues detected were p,p’ DDT, p,p’ DDE, and Hexachlorobenzene. While, the most abundant PCBs detected congeners were PCB 138, 153, 170, 180, and 187. Although the general structure of the eggshell layers was maintained, the results showed ultrastructural differences in mammillary and palisade eggshell layers between high level and low level contaminated eggs in Tyto alba. Furthermore, mammillary cores of the eggshell had an increased distance between themselves with respect to well organized structures present in uncontaminated egg. In this paper we verify the presence of environmental contaminants in the eggs and document structural changes in bird of prey eggshells. The data could suggest that some contaminants can contribute to reduced reproductive performance (infertile or addled egg) by structural changes in the eggshell. The alteration in morphological disposition of mammillary cores could also suggest an impairment of gas exchange.

The Eye in the Sky: Combined Use of Unmanned Aerial Systems and GPS Data Loggers for Ecological Research and Conservation of Small Birds

Technological advances for wildlife monitoring have expanded our ability to study behavior and space use of many species. But biotelemetry is limited by size, weight, data memory and battery power of the attached devices, especially in animals with light body masses, such as the majority of bird species. In this study, we describe the combined use of GPS data logger information obtained from free-ranging birds, and environmental information recorded by unmanned aerial systems (UASs). As a case study, we studied habitat selection of a small raptorial bird, the lesser kestrel Falco naumanni, foraging in a highly dynamic landscape. After downloading spatio-temporal information from data loggers attached to the birds, we programmed the UASs to fly and take imagery by means of an onboard digital camera documenting the flight paths of those same birds shortly after their recorded flights. This methodology permitted us to extract environmental information at quasi-real time. We demonstrate that UASs are a useful tool for a wide variety of wildlife studies.

Impact of temperature on the breeding performance and selection patterns in lesser kestrels Falco naumanni

Adjusting breeding phenology to climate fluctuations can be problematic for migratory birds as they have to account for local environmental conditions on the breeding grounds while migrating from remote wintering areas. Predicting general responses to climate change is not straightforward, because these responses vary between migrant species due to the species‐specific ecological drivers of breeding behaviour. Therefore more information is needed on species with different ecological requirements, including data on heritability of migration, factors driving phenological changes and how climate affects selection pressures.Here, we measure heritability in settlement dates and the effect of local climate at the breeding grounds on settlement dates, reproductive success and selection patterns in a French population of a trans‐Saharan migratory insectivorous raptor, the lesser kestrel Falco naumanni, monitored and ringed since 1996.Heritability of settlement dates was low (0.07 ± 0.03), indicating a weak evolutionary potential. Nevertheless, plasticity in settlement dates in response to temperatures allowed earlier settlement when early spring was warmer than average. Reproductive success and selection patterns were strongly affected by temperature during settlement and chick rearing respectively. Warmer spring decreased selection for earlier settling and warmer early summer increased reproductive success. Interestingly, selection for earlier settling was more intense in cooler springs, contrasting with patterns from passerines lagging behind food peaks.Altogether, these results suggest a positive effect of warmer temperatures on breeding performances of lesser kestrels most likely because the French population is at the coolest boundary of the species European breeding range.

Male transmission ratio distortion supports MHC-linked cryptic female choice in the lesser kestrel (Aves: Falconidae)

Major histocompatibility complex (MHC) are classical examples of good genes because of their crit- ical participation in fighting and eradicating pathogens. Here, we investigated the inheritance of alleles across a highly polymorphic MHC class II B gene in a socially monogamous raptor, the lesser kestrel Falco naumanni. Allele segregation patterns from parents to offspring were monitored in 44 breeding pairs and 228 nestlings. We found that a particular array of closely related alleles, defined by the presence of two of the three commonest alleles (only three alleles exhibit frequencies larger than 10 % in the studied populations), showed significant transmission ratio distortions when inherited from males (k00.702±0.188, p<0.001), but not when inherited from females (k00.563±0.207, p00.19). We believe that this result is consistent with the targeting of genetically loaded spermatozoa by female kestrels. Our anal- yses do not allow discerning, however, whether this pattern is predominantly driven by sperm competition or differential maternal allocation. This trend, nonetheless, would agree with the contrasting relative frequencies of these alleles between western and eastern populations of lesser kestrels and sustains their contemplation as locally adapted alleles, as suggested in previous studies. Ours is one of the very few studies support- ing the MHC-based female cryptic choice in birds and opens inspiring lines of research. In particular, future studies addressing the influence of candidate MHC alleles on indi- vidual fitness and their effect on maternal adjustments associ- ated with reproduction should be encouraged.

Mapping the migratory routes and wintering areas of Lesser Kestrels Falco naumanni: new insights from satellite telemetry

Recent improvements in satellite tracking, such as the miniaturization of transmitters, have enabled the study of movements of an increasing number of bird species. The Lesser Kestrel Falco naumanni has been the subject of numerous studies but detailed information on its migration routes and wintering areas is still lacking. Here, we provide a detailed description of migration routes, timing of migration and wintering areas of Lesser Kestrels. Five adults fitted with satellite transmitters in southeastern Spain were tracked during autumn and spring migration journeys and on their wintering grounds. The overall migration duration was longer in spring than in autumn, although birds also showed longer stopovers in this season and hence the number of travelling days was lower. Lesser Kestrels covered longer daily distances in spring due to a higher frequency of nocturnal migration, rather than differences in flight speed, which did not differ between seasons. Wintering areas of Lesser Kestrels from the same breeding colony were widely spaced throughout the western Sahel along the borders of Mauritania, Mali and Senegal, approximately 2800 km from their breeding sites. The autumn migration duration of Lesser Kestrels derived from recent studies using geolocators was underestimated compared with that recorded by satellite telemetry. Given the current rapid habitat loss in the Sahel, a better understanding of migratory routes and wintering areas of other populations of this species would be important to assess its influence on population trends.

Landscape and weather determinants of prey availability: implications for the Lesser Kestrel Falco naumanni

Spatial and temporal variation in prey abundance have been shown to impact the time of breeding and breeding success of birds. Understanding the ecological requirements of preferred prey can help develop management measures to improve food supply for target species. For the colonial Lesser Kestrel Falco naumanni, mole crickets Gryllotalpa spp. are one of the most important prey items during the mate‐feeding period. Lesser Kestrel colonies with higher mole cricket consumption had earlier egg‐laying dates, suggesting that differences between individuals in the time of breeding could be caused by differences in the diet. Moreover, the mean number of mole crickets in pellets was significantly correlated with clutch size (in one of the studied years) and egg volume. Thus, the impact of environmental variables and land use on mole crickets is likely to be relevant to Lesser Kestrel conservation. Weekly consumption of mole crickets was higher following an increase in either precipitation or minimum temperature values. Furthermore, mole cricket consumption was higher in colonies surrounded by higher quality soils and in wetter areas and years. Predicted probability of mole cricket occurrence in surveyed watercourse margins suggested a positive relationship between soil penetrability and mole cricket occurrence. Among variables that might be the target of management, the presence of riparian vegetation positively influenced the occurrence of mole crickets, whilst tillage and sowing of streambeds were revealed as the most important threats. We suggest that the maintenance of native vegetation in the margins of watercourses could improve soil resilience to erosion, increase water retention, soil penetrability and fertility, and provide a food supply and shelter for mole crickets. Overall, the implementation of such recommendations is likely to benefit other farmland species known to consume mole crickets, including several endangered species.

Influence of spatial and temporal dynamics of agricultural practices on the lesser kestrel

Summary1. European agriculture is facing dramatic changes that are likely to have marked impacts on farmland biodiversity. There is an urgent need to develop land management strategies compatible with the conservation of biodiversity.2. We applied a spatially explicit behaviour‐based model to assess how farmland management and the pattern of events across the annual farming calendar influences the foraging decisions of lesser kestrelsFalco naumanniin a cereal steppe landscape. Moreover, we simulated the most likely scenarios of future agricultural changes to predict its impacts on lesser kestrel breeding success. Lesser kestrels have been the subject of serious conservation concern and constitute a good model species to judge impacts on farmland species more widely.3. Our results show that the location of cereal and fallow patches within a 2‐km radius of a kestrel colony influences the total food supply delivered to the nestlings, explaining the differences in breeding success between years and colonies. Furthermore, the particular sequence in which patches are harvested by farmers is also predicted to influence offspring survival.4. Agricultural intensification, simulated by increasing the proportion of cereal fields, is predicted to negatively influence breeding success. However, the field harvesting sequence can play an important role in alleviating the effects of the increased percentage of cereal, as demonstrated by the higher breeding success obtained when harvesting starts from patches farthest from the colonies. The replacement of cereal cultivation by low‐intensity grazed fallows would not be detrimental for kestrels.5. Synthesis and applications. Our results highlight the effectiveness of behaviour‐based models to evaluate the interacting effect of spatial and temporal dynamics of agricultural landscapes and predict the response of populations to environmental change. To optimize food availability for lesser kestrels, land managers should implement long rotational schemes with &lt;60% of the area under extensive cereal cultivation in a 2‐km radius around colonies. Harvesting should start in the cereal patches farthest from colonies. Ideally, the predominant land use around colonies should be fallows. These outcomes illustrate how behaviour‐based models can be applied to identify specific management recommendations that would improve the effectiveness of agri‐environmental schemes, the most accepted tool for maintaining farmland landscapes.

Autumn migration of soaring birds through the Gebel El Zeit Important Bird Area (IBA), Egypt, threatened by wind farm projects

SummarySystematic bird observations were performed during autumn 2006 in the migration bottleneck area of Zeit Bay, Egypt (27.73°N, 33.51°E), situated on the coast of the Gulf of Suez, opposite southern Sinai. Owing to the strong northerly winds in that area, considerable pressure exists to construct wind farms. A total of 145,432 soaring birds, including 134,599 storks and 9,376 raptors over a period of 453.6 hours were observed between 20 August and 29 October by two teams working daily in two shifts. White Stork Ciconia ciconia and European Honey Buzzard Pernis apivorus were the most numerous species (91.4% and 5.7% respectively) of all soaring birds observed. As both species migrate early, relatively few birds were recorded passing through in October. A total of 57,179 soaring birds were observed within a range of 2.5 km from the observers, and of these 32,248 were flying at heights up to 200 m. Few individuals of the rapidly declining breeding populations of Egyptian Vulture Neophron percnotperus (‘Endangered’) and Lesser Kestrel Falco naumanni (‘Vulnerable’) passed (8 and 33 respectively). Pallid Harriers Circus macrourus (‘Near Threatened’) however, were more numerous (100) than at other migration sites along the East African-West Asian Flyway (Israel, southern tip of Sinai, Suez and Bab-el-Mandeb). Western Marsh Harrier Circus aeruginosus and Montagu’s Harrier Circus pygargus were also more numerous than at these sites. Some other large migrant species, observed at Suez, Bab el-Mandeb or in Israel, were seen only in small numbers or not at all at Zeit Bay in autumn. Among them, the Steppe Eagle Aquila nipalensis being the best known example of loop migration, entering Africa at Suez and Bab el-Mandeb, is for this reason not expected in autumn at Zeit Bay, while in spring it is a regular migrant. The number of Black Storks Ciconia nigra observed accounted for 4.8% of the flyway population, that of White Storks for 33.3%, Great White Pelicans Pelecanus onocrotalus for a further 3.5% and European Honey Buzzards for 0.8%. The extrapolation of the number of birds passing through the study area during the migration season, suggests that it was used by 92% of the White Stork, 12% of the Black Stork, 5% of the Great White Pelican, 4% of the European Honey Buzzard and 2% of the Pallid Harrier flyway populations in autumn 2006.

Sources of variation for nutritional condition indices of the plasma of migratory lesser kestrels in the breeding grounds

Although published information on reference values for biochemical parameters in birds of prey has increased during the last years, little is known on their sources of variation. We used an insectivorous and small migratory raptor species, the lesser kestrel Falco naumanni, as a model. We looked for sources of variation of nutritional biochemical parameters (i.e. triglycerides, cholesterol, uric acid and urea) of both nestlings and adults. Reference values indicated that, as a rule, lesser kestrel showed more elevated triglycerides, urea and uric acid levels than other raptors. All analyzed factors except gender (i.e. year, colony, sampling time, presence/absence of a geolocator, body mass, laying date and capture date) reached significance for at least one biochemical parameter. In the morning, we found an important postprandial increase in the concentration of all biochemical parameters in nestlings, and uric acid and urea levels in adults. A positive relationship was detected between triglycerides and body mass in nestlings and adults. Although we did not find differences between blood biochemical parameters of the oldest and youngest chick of each brood, we found that cholesterol levels were lower in nestlings from larger broods. Coloration of tarsi (measured as brightness) was related to triglycerides and urea levels of nestlings and adults, respectively. The feeding habits of lesser kestrel probably explain the different levels and patterns of variation of metabolites in comparison to more carnivorous raptors eating mammals or birds.

Lifetime fitness correlates of natal dispersal distance in a colonial bird

1. Obtaining empirical evidence of the consequences of dispersal distance on fitness is challenging in wild animals because long-term, unbiased data on reproduction, survival and movement are notoriously difficult to obtain. 2. Lifetime fitness correlates of natal dispersal distance were studied in an isolated population of the facultatively colonial lesser kestrel Falco naumanni (Fleischer) monitored during 8 years at north-eastern Spain, where most birds (83%) dispersed from their natal colony to settle at distances ranging from 112 m to 136.5 km. 3. Neither annual breeding success nor age at recruitment was affected by natal dispersal distance. However, a capture-mark-recapture analysis revealed that survival during the year following recruitment decreased exponentially with dispersal distance, with differences of up to 15% between philopatrics and long-distance dispersers. In subsequent years, it remained similar irrespective of the natal dispersal distance moved. These results did not seem to be biased by long-distance dispersers settling differentially in the periphery of the population (which could emigrate permanently and be considered dead in future occasions) or within-individual consistency in successive dispersal distances, so our results appear to reflect genuine survival differences between dispersal tactics. 4. Average lifetime fledgling production, average lifetime recruitment success and rate-sensitive individual fitness (λ(ind)) also decreased with the distance from the natal to the first-breeding colony, indicating that dispersal decisions early in life affecting immediate survival prospects may translate into long-term fitness costs. 5. Both survival and lifetime fitness models including continuous dispersal distances significantly improved the characterization of the effect on fitness compared with models considering dispersal as a discrete process (i.e. dispersal vs. philopatry at a colony level). 6. Long-distance dispersers were more likely to establish new colonies regardless of whether they recruited in the centre or the periphery of the population, revealing their important role in the colonization of unoccupied patches. Individuals experienced a higher probability of mortality in small and newly funded colonies, so lifetime fitness costs of dispersal seem to be explained by recruitment in sites where average quality is low because of high uncertainty in survival prospects.

Molecular Evolution of the Toll-Like Receptor Multigene Family in Birds

Toll-like receptors (TLR) are membrane-bound sensors of the innate immune system that recognize invariant and distinctive molecular features of invading microbes and are also essential for initiating adaptive immunity in vertebrates. The genetic variation at TLR genes has been directly related to differential pathogen outcomes in humans and livestock. Nonetheless, new insights about the impact of TLRs polymorphism on the evolutionary ecology of infectious diseases can be gained through the investigation of additional vertebrate groups not yet investigated in detail. In this study, we have conducted the first characterization of the entire TLR multigene family (N = 10 genes) in non-model avian species. Using primers targeting conserved coding regions, we aimed at amplifying large segments of the extracellular domains (275-435 aa) involved in pathogen recognition across seven phylogenetically diverse bird species. Our analyses suggest avian TLRs are dominated by stabilizing selection, suggesting that slow rates of nonsynonymous substitution help preserve biological function. Overall, mean values of ω (= d(n)/d(s)) at each TLR locus ranged from 0.196 to 0.517. However, we also found patterns of positive selection acting on specific amino acid sites that could be linked to species-specific differences in pathogen-associated molecular pattern recognition. Only 39 of 2,875 (∼1.35%) of the codons analyzed exhibited significant patterns of positive selection. At least one half of these positively selected codons can be mapped to putative ligand-binding regions, as suggested by crystallographic structures of TLRs and their ligands and mutagenic analyses. We also surveyed TLR polymorphism in wild populations of two bird species, the Lesser Kestrel Falco naumanni and the House Finch Carpodacus mexicanus. In general, avian TLRs displayed low to moderate single nucleotide polymorphism levels and an excess of silent nucleotide substitutions, but also conspicuous instances of positive directional selection. In particular, TLR5 and TLR15 exhibited the highest degree of genetic polymorphism and the highest occurrence of nonconservative amino acid substitutions. This study provides critical primers and a first look at the evolutionary patterns and implications of TLR polymorphism in non-model avian species and extends the list of candidate loci for avian eco-immunogenetics beyond the widely employed genes of the Major Histocompatibility Complex (MHC).

Using major histocompatibility complex markers to assign the geographic origin of migratory birds: examples from the threatened lesser kestrel

AbstractGathering knowledge about the migratory routes and wintering areas of threatened populations is fundamental for their successful conservation. Here, we used a non‐invasive approach that relies on major histocompatibility complex (MHC) polymorphism to infer the breeding origin of a long‐distance migratory bird, the lesser kestrel Falco naumanni, in its most important wintering quarters in the Sub‐Saharan Africa (Senegal and South Africa). Private alleles support a strong connectivity between wintering Senegalese and western European breeding populations. On the other hand, birds wintering in South Africa were genetically differentiated with respect to western European breeding populations and might therefore gather individuals from the eastern distribution range. This study demonstrates that, at least at wide continental scales, MHC genes can be powerful intrinsic markers to study migration and migration connectivity, thus adding value to its role in conservation and management.

Is there enough habitat for reintroduced populations of the Lesser Kestrel? A case study in eastern Spain

SummaryThe Lesser Kestrel Falco naumanni is one of the most endangered birds in Europe. Spanish populations have suffered large declines and disappeared from large areas of former distribution, thus leading to many reintroduction programmes. One of the main factors that could affect the population growth of reintroduced populations is the availability of suitable habitat for breeding and foraging. We investigated whether nest site availability is a limiting factor for a newly established population of Lesser Kestrels in eastern Spain. We developed univariate models to understand the relationship between building characteristics (area, height, roof condition, etc.) and occupancy and abundance of Lesser Kestrels, and multivariate models to predict the availability of nest-sites. Our results showed that the species selected medium-sized buildings with extensive land use in the surrounding area and an absence of trees. In addition, Lesser Kestrel abundance was explained by roof condition and distance to the nearest building. Multivariate models predicted that most of the buildings were not suitable for nesting by Lesser Kestrels and thus population growth may be limited due to lack of nest sites. Lack of suitable nest sites, conspecific attraction and Allee effects are all processes that may be limiting, resulting in the low population and colony sizes that were found and predicted. Based on this, we recommend the provision of nest boxes, the use of special tiles and the construction of breeding towers to improve building quality and therefore increase colony size. We also critically question the use of reintroduction projects to restore locally extinct populations for two reasons. First in this case the reintroduced population is near some larger colonies and there is a strong tendency for Lesser Kestrels to move from small to large colonies. Secondly, in a general strategy for the conservation of Lesser Kestrels, conservation of the main colonies is the priority rather than dedicating human and economic resources on manipulative actions for the establishment of new colonies.

Mechanisms of colony selection by first‐year Lesser Kestrels Falco naumanni

In colonial species, first‐time breeders may use the number of settled conspecifics in colony selection, but such a relationship is confused by the correlation between colony size and nest‐site availability. To distinguish conspecific attraction from neutral colony selection, we experimentally increased nest availability for first‐year Lesser Kestrels Falco naumanni, allowing us to dissociate the number of vacant nest‐sites from colony size at the arrival time of first‐year birds. Under natural conditions, the number of first‐year birds settling was positively correlated with both the number of philopatric and the total number of breeding pairs (colony size) already settled. However, the probability of occupation of experimentally manipulated nests by first‐year birds was independent of colony size. In experimental colonies, the number of first‐year birds settling was positively correlated with the number of manipulated nest‐sites but not with the number of conspecifics. Overall, these results support a neutral colony selection by first‐year Lesser Kestrels based on nest‐site availability.