First breeding of lesser kestrel <i>Falco naumanni</i> in Campania

The lesser kestrel (Falco naumanni) is a small falcon with a Euro-Central and Asian-Mediterranean range wintering in sub-Saharan Africa. In the second half of the 20th century, the European population experienced a steep decline and was classified as at risk; thus, its biological and ecological aspects have been widely investigated. Nonetheless, data on hematology and plasma chemistry are not yet available. Therefore, hematology and biochemistry parameters were investigated in a sampling population of clinically healthy lesser kestrels (21 female and 10 male adults) from an Italian rescue center during breeding season, estimating the 95% (2.5 - 97.5th percentile) reference intervals (RI) for standard tests based on either parametric or robust statistical methods. The effect of sex on the referenced parameters was also tested and showed no statically significant differences. The established 95% RI highlighted values comparable with those of other similar raptors such as American kestrel (Falco sparverius) and peregrine falcon (Falco peregrinus). As the first recorded hematology and serum chemistry RI, these clinical data could support conservation efforts and clarify the effects of various environmental and ecological factors on the clinical and health status of lesser kestrels, although they should be reinforced with further data from healthy wild animals.

Diet composition of lesser kestrels in Ikh Nart Nature Reserve, Mongolia

The Lesser Kestrel (Falco naumanni) is a small migratory falcon which nests coloni- ally on inland cliffs and ruined buildings. Bandar Turkman city holds one of the most important breeding colonies in Iran. It nests in holes in roofs, walls or on ledges of buildings throughout of the city. We tried to find out whether there is a relationship between nest-site selection and breeding success. Although height from the ground is the most important factor in nest-site selection by F. naumanni, height from the floor and distance to the nearest neighbour are other main factors which affect breeding success. This could be the result of accessibility by human and natural predators such as domestic cats which threaten nests. The number of possible nest-sites in the study area is limited as many old, ruined buildings are being replaced by new construc- tions; this colonially breeding bird species therefore suffers from a lack of highly suitable nest-sites and this directly affect breeding success.

Climate warming would theoretically create conditions for the breeding range expansion of pseudo‐steppe Mediterranean and long‐distance migrant species and provide the possibility for these to overwinter in the same breeding areas. However, contemporary changes in rainfall regimes might have negative effects on the climate suitability and in turn, shrink species potential range. The lesser kestrel Falco naumanni is highly sensitive to rainfall oscillations and has recently extended its Italian breeding range towards northern latitudes and increasing its wintering records. We modelled the effects of temperature and rainfall on current and future climate suitability for lesser kestrels in both the breeding and wintering periods by using MaxEnt. Models were based on the distribution of 298 colonies and 40 wintering records. Future climate suitability was assessed under eight different scenarios.Spring rainfall amount resulted as the main determinant of breeding climate suitability, so its predicted reduction will determine a shrinkage in suitable areas (–42.10% in 2050; –32.07% in 2070). Specifically, the 66.05% of Italian colonies will be outside the climatically suitable area by 2050. However wide areas, suitable under current climate conditions, are still not occupied by lesser kestrel and allow the potential expansion of its Italian breeding range in the short term. Temperature seasonality mainly determined the species’ winter climate suitability, which is overall predicted to boost in the next decades (+145.03% in 2050; and +123.91% in 2070). All but one future scenarios predicted a northward shift of about 40 km for both breeding and wintering climate suitability. Despite its recent expansion, we have found that climate change will pose conservation concerns for the Italian breeding population of lesser kestrels. Indeed, changes in non‐climate factors will also outline the future suitability of the Italian range for lesser kestrels in both seasons with effects that might both strengthen or mitigate climate effects.

A timeline for the urbanization of wild birds: The case of the lesser kestrel

Population fragmentation is a widespread phenomenon usually associated with human activity. As a result of habitat transformation, the philopatric and steppe-specialist Lesser Kestrel Falco naumanni underwent a severe population decline during the last century that increased population fragmentation throughout its breeding range. In contrast, the ubiquitous Eurasian Kestrel Falco tinnunculus did not suffer such adverse effects, its breeding range still remaining rather continuous. Using microsatellites, we tested the effects of population fragmentation on large-scale spatial patterns of genetic differentiation and diversity by comparing these two sympatric and phylogenetically related species. Our results suggest that habitat fragmentation has increased genetic differentiation between Lesser Kestrel populations, following an isolation-by-distance pattern, while the population of Eurasian Kestrels is panmictic. Contrary to expectations, we did not detect significant evidence of reduced genetic variation or increased inbreeding in Lesser Kestrels. Although this study reports genetic differentiation in a species that has potential for long-distance dispersal but philopatry-limited gene flow, large enough effective population sizes and migration may have been sufficient to mitigate genetic depauperation. A serious reduction of genetic diversity in Lesser Kestrels would, therefore, only be expected after severe population bottlenecks following extreme geographic isolation.

Migratory connectivity describes the linkage between breeding and nonbreeding sites, having major ecological implications in birds: 1 season influence the success of an individual or a population in the following season. Most studies on migratory connectivity have used large-scale approaches, often considering regional populations, but fine-scale studies are also necessary to understand colony connectivity. The lesser kestrel Falco naumanni, an insectivorous migratory raptor which form colonies during the breeding period, was considered to have strong connectivity based on regional populations. However, no small-scale studies on migratory connectivity have been conducted. Therefore, we GPS (Global Positioning System)-tracked 40 adult lesser kestrels from 15 different Spanish breeding colonies, estimating the overlap index between home ranges and the distance between their centroids. It was found that lesser kestrels from the same breeding colony placed their nonbreeding areas at 347 ± 281 km (mean ± standard deviation) away from each other (range = 23-990), and their home ranges overlapped by 38.4 ± 23.6%. No differences between intra-colony and inter-colony metrics were found, which suggests that lesser kestrels from the same breeding cluster do not overwinter together, but they spread out and mixed independently of the colony belonging throughout the nonbreeding range of the species. Ultimately, this study highlights the importance of performing connectivity studies using fine-scale approaches.

Climate warming and land-use change are reshuffling the distribution of wild organisms on a global scale. Some species may expand their ranges and colonize new regions, which may greatly affect ecological interactions among pre-existing species and colonizers. In the last decades, such processes have originated a unique condition of sympatry among three Eurasian small Falco species (common kestrel F. tinnunculus, lesser kestrel F. naumanni, red-footed falcon F. vespertinus) in the intensively cultivated farmland habitats of the Po Plain (Northern Italy). This provides an excellent opportunity to investigate patterns of spatial niche overlap during the initial phases of the establishment of sympatry. To investigate spatial niche overlap of the three falcon species, we relied on Environmental Niche Models (ENMs) based on widespread breeding occurrence data obtained through field surveys and citizen science programs (during the 2018–2020 period). ENMs were based on bioclimatic and land-use variables in an ensemble modelling framework. We estimated species-specific relative contributions of each climatic and land-use variable and its response curves effect. Eventually, we generated spatial correlation maps of the potential species’ distributions to derive spatially-explicit predictions of potential co-occurrence areas among the three species. Overall, eco-climatic determinants of the distribution of lesser kestrel and red-footed falcon were similar, resulting in a strong association with intensive arable lands and dry continental climate. Consistently, we found a high spatial correlation between the suitability maps of the two species, with highly suitable areas located in the Central-Eastern area of the Po Plain, corresponding to the core range of both species. Conversely, the common kestrel emerged as a habitat generalist and was widely distributed throughout the Po Plain. Our findings suggest that the recent sympatry between lesser kestrels and red-footed falcons in the Po Plain may promote ecological interactions and intra-guild competition.

Captive breeding of different species of birds offers conservationists a viable option when it comes to boosting wild populations of rare endangered species. Including non-releasable animals with permanent injuries can increase the breeding flock and breeding output. In addition, it provides an opportunity for birds that cannot be released to be included in conservation activities by rearing offspring for release in the wild. Between 2013 and 2024, in Bulgaria in the Wildlife Rehabilitation and Breeding Centre, part of Green Balkans - Stara Zagora NGO, individuals from three species of small falcons were paired for breeding - the pairs included birds with permanent disabilities of Lesser Kestrels, Common Kestrels and Red-footed Falcons. For the study period, 34 Lesser Kestrels - offspring to injured pairs, were reared and released into the wild in the country, together with 172 Common Kestrels and two Red-footed Falcons. The breed-and-release activities contributed to reinforcing the wild populations of the falcon species and to improving the skills and knowledge of aviculturists and veterinarians in Bulgaria dealing with birds of prey.

The population decline of the Lesser Kestrel Falco naumanni has been the subject of studies across its Western Palaearctic breeding range, but little is known about its use of pre‐migratory areas or African wintering quarters. We used geolocators to describe the temporal and spatial patterns of Portuguese Lesser Kestrel migration and wintering behaviour. Data on the complete migration were obtained from four individuals and another three provided further information. Prior to southward migration, Lesser Kestrels showed two different behaviours: northward‐orientated movements to Spain and movements in the proximity of the breeding area. Autumn migration took place mostly in late September; spring departures occurred mainly in the first half of February. Wintering grounds included Senegal, Mauritania and Mali, with individuals overlapping considerably in Senegal. Movements registered within the wintering grounds suggest itinerant behaviour in relation to local flushes of prey. During spring migration, birds crossed the Sahara Desert through Mauritania, Western Sahara and Morocco before passing over the Mediterranean to reach Portugal. Autumn migration lasted 4.8 ± 1.1 days, and spring migration lasted 4.1 ± 0.3 days. The mean daily flight range varied between approximately 300 and 850 km for an entire journey of around 2500 km. Effective protection of roosting sites in both pre‐migratory and wintering areas and maintaining grasshopper populations in Sahelian wintering quarters appear crucial in preserving this threatened migratory raptor across its African–Eurasian flyway. There was no evidence of any deleterious effects of fitting birds with loggers.

Summary In the middle of the 20th century the colonial lesser kestrel Falco naumanni experienced a marked decline in its western palaearctic breeding range. Although this decline has been attributed to changes in land use influencing breeding success through lowering the abundance and quality of prey, a quantification of these effects has not yet been undertaken. To study how these two key factors influence breeding success, we developed an individual‐based model, which translates the hunting performance of each adult foraging trip into nestling growth and enables the effect of crop types on the breeding success of the lesser kestrel to be quantified. Both the authors’ own field data and published inferential and experimental studies were used to parameterize and validate the growth model. Model results demonstrated that adult provisioning rates provide very little information on the relation between prey availability and breeding success. On the other hand, the model indicated that small differences in prey abundance among crop types cause large differences in breeding success, highlighting the importance of crop composition in the vicinity of lesser kestrel colonies. Mean prey biomass is an even more important influence on breeding success. Our results indicated a minimum mean prey size of 0·6 g, below which colonies become population sinks. Synthesis and applications. We developed an individual‐based model that simulates the growth in body mass of a lesser kestrel brood as a function of prey abundance and prey size. These two key factors define a parameter space in which the conservation status of breeding colonies can be evaluated. We applied the model to six lesser kestrel breeding colonies with different mean prey size and different agricultural land use influencing prey abundance. Our model suggests that the habitat quality of two of these colonies is sufficient for population persistence, while management actions to increase habitat quality are required in the remaining four colonies. An increase in the availability of prey‐rich habitats such as field margins would achieve this goal without imposing too great a cost on the local farming community.

Habitat selection in animals is a fundamental ecological process with key conservation implications. Assessing habitat selection in endangered species and populations occupying the extreme edges of their distribution range, or living in highly anthropized landscapes, may be of particular interest as it may provide hints to mechanisms promoting potential range expansions. We assessed second- and third-order foraging habitat selection in the northernmost European breeding population of the lesser kestrel (Falco naumanni), a migratory falcon of European conservation interest, by integrating results obtained from 411 direct observations with those gathered from nine GPS-tracked individuals. The study population breeds in the intensively cultivated Po Plain (northern Italy). Direct observations and GPS data coincide in showing that foraging lesser kestrels shifted their habitat preferences through the breeding cycle. They positively selected alfalfa and other non-irrigated crops during the early breeding season, while winter cereals were selected during the nestling-rearing phase. Maize was selected during the early breeding season, after sowing, but significantly avoided later. Overall, vegetation height emerged as the main predictor of foraging habitat selection, with birds preferring short vegetation, which is likely to maximise prey accessibility. Such a flexibility in foraging habitat selection according to spatio-temporal variation in the agricultural landscape determined by local crop management practices may have allowed the species to successfully thrive in one of the most intensively cultivated areas of Europe. In the southeastern Po Plain, the broad extent of hay and non-irrigated crops is possibly functioning as a surrogate habitat for the pseudo-steppe environment where most of the European breeding population is settled, fostering the northward expansion of the species in Europe. In intensive agricultural landscapes, the maintenance of alfalfa and winter cereals crops and an overall high crop heterogeneity (deriving from crop rotation) is fundamental to accommodate the ecological requirements of the species in different phases of its breeding cycle.

The lesser kestrel Falco naumanni is a facultative colonial falconiform whose breeding range stretches across the entire Palaearctic. As with other pseudo-steppe birds, the lesser kestrel has experienced a sharp decline in western Europe over the last decades, spurring conservation actions. We compared natal philopatry of captive versus wild-bred individuals and the effect of release date on philopatry by comparing return data of captive- and wild-bred kestrels from 13 colonies between 2004 and 2019. We found that wild-bred kestrels show significantly stronger philopatry than their captive-bred counterparts, possibly due to the lack of parental influence experienced by the latter during their first days. No relationship was detected between release date and natal philopatry. Future studies should focus on factors affecting the philopatric behaviour of lesser kestrels bred in captivity, which could in turn improve their captive breeding and release strategy.

The lesser kestrel is a small colonial falcon with a broad breeding distribution range, extending from the Iberian Peninsula to eastern China. Most of the biological and ecological knowledge concerning this species, including migration, has been obtained from European populations. After the end of each breeding season, these populations move preferentially northward, showing pre-migratory movements (of 100-1,000 km) that are necessary to reach rich foraging grounds where they can fuel before commencing the true migration towards Africa. European lesser kestrels migrate on a broad front across the Mediterranean Sea. There is a strong connectivity between European breeding and African non-breeding grounds, with different populations being clearly segregated also during winter. Iberian lesser kestrels show a rather different migration phenology (i.e., earlier departures and shorter travels) compared to other European birds, likely due to the geographic conformation of continents and greater proximity to wintering areas. Tracking data indicate that departures span across two months, averaging ca. September 20th. After ca. 12 days of travel, individuals arrive in the Sahel where they stay 5-6 months. The spring migration routes are similar to autumn ones, being however less straight, with more pronounced westward detours and crossings in proximity of the Gibraltar and Sicily Straits. Spring departures are concentrated in the first two weeks of March. Spring travels usually last longer than autumn ones, i.e., 18-23 days, with more time spent on stopover. The pattern of migration of Middle East and Asian populations is mostly based on anecdotal information.

We examined the breeding success of Lesser Kestrels Falco naumanni in Ikh Nart Nature Reserve, a semi-desert zone in southeast Mongolian. We found that the mean number of nests per colony was 7.4. Lesser Kestrels laid eggs between 24 May and 2 June each year. Mean clutch size was 4.0±0.7 SE, with a mean incubation period of 28±2 SE days. We recorded an overall hatching success rate of 84.2% and overall fledgling success rate of 89.7%, hence a mean fledgling per breeding attempt was 2.79. Our findings revealed relatively high hatching and fledgling rates for our study population, and bode well for the conservation of this small falcon in its poorly-known breeding range.