This chapter gives an overview of the embryonic development and morphological characteristics of the Little Owl. We first look at how the egg develops, with special attention paid to the temporary asymmetric ears, then zoom in on owlet development as they grow and the plumage of adult birds and how molt takes place. The eyes are special and the species has retinal cells similar to diurnal birds of prey. While Little Owls can differentiate several colors, the species does not see infra-red rays. It has an auditory sensitivity to locate small rodents with an accuracy of up to 1%. The bill is yellowish and its color functions as a signal for the fitness of both juveniles and adults. The Little Owl has differential biometrical measures (such as length of wing, tail, tarsus) according to the subspecies or according to the sex (such as weight - females are heavier close to the breeding time). We finally examine the voice. The species has a large vocal repertoire, including 40 acoustic signals and combinations with regional specificities. The chapter concludes with specific characteristics for flight and the anatomy.

Little Owls have been shown to be directly and indirectly affected by habitat loss, vehicle collisions, limited availability of nest and roosting sites, pesticides (i.e., secondary poisoning) and heavy metals, entrapment in anthropogenic structures (i.e., hollow metal power poles and chimneys, and drowning in water troughs), predators and weather. They are susceptible to parasites, diseases and injuries too. While the Little Owl has co-evolved with a few of these (e.g., weather, predators, diseases, parasites), anthropogenic activities have substantially altered the landscape within which Little Owls exist(ed). When the population grows and owl densities become higher, density-dependent processes take place and serve to stabilise the population. In a metapopulation context, as populations become increasingly small, immigration helps to support them, extending the survival time of these population clusters. The mating system hypothesis, which predicts that the sex that establishes the territory should disperse shorter distances, was studied using the EURING data set containing 108 444 observations of ringing, re-capture and recovery data for 59 743 unique ringed birds. Little Owls ringed as young and recovered at least one year later dispersed on average 14.69 km for females, 6.47 km for males and 11.61 km for birds with unknown sex for live re-captures. Birds ringed as adults and then later recovered dispersed 2.33 km for females, 2.45 km for males and 2.42 km for birds with unknown sex for live re-captures.

The framework of this book reflects the complexity of the situation of the species at different scales. To position the Little Owl in the cultural context we look at the history and cultural traditions connected to the species. We describe the taxonomy and subspecies to settle some taxonomic discussions of the species based upon major genetic, morphological and biogeographical findings. The distribution of the different subspecies and recent population estimates for the Western Palearctic are given to illustrate the geographic diversity. The habitat is described and its relationships with the species. Food as principle biotic factor delivers the crucial energy input for the birds. Abiotic factors such as breeding cavities and perches show their importance for breeding and foraging efficiency to minimize the energetic cost. Next we focus on the breeding season, discussing clutch size, hatching and fledging success in relation to the age of the birds. We then describe behavior mainly based upon two decades of webcam observations. Next we zoom in on limiting factors that influence populations in a given geographic environment, e.g., immigration, re-introduction or supplementation, and mechanisms of interaction between local populations, such as migration, meta-populations and sinks/sources. After describing the main causes for declines in the species, we summarize knowledge into a conservation and management strategy. We conclude this chapter with an overview of the key points raised, with an overview of the most important open questions and suggestions for future studies.

New media such as internet-connected cameras in nestboxes can yield infra-red images in the dark leading to new insights and knowledge. Substantial new information has become available from the groundbreaking webcam project of Vogelbescherming Nederland Beleef de Lente that started in 2007 and continues to this day. Volunteers select video clips revealing as yet undiscovered remarkable behavior over 14 entire breeding seasons, day and night, from courtship to egg-laying, to the fledging of the young. Due to simpler and cheaper technology, more and more people have decided to install such cameras in their nestboxed which is expected to yield even more new knowledge in the future, opening unprecedented opportunities for citizen science. This chapter is complemented by a lot of information from the long-term research of Van Harxen and Stroeken (from 1986) in their study area in Southeast Achterhoek in the Netherlands.

This chapter covers the entire Little Owl breeding cycle. The breeding season is obviously a critically important period during which reproduction can be influenced by many different factors, such as weather, food, habitat, density, geographical location and parental experience. The season begins in January or February with the affirmation of territorial boundaries and onset of courtship. The Little Owl does not have high a productivity due to very few replacement clutches, moderate fledging success and relatively high egg failure. According to the mortality rate of adults and juveniles, each pair should produce between 1.7 and 2.34 fledged young per year to compensate mortality and actually most of the long-term breeding studies across Europe show results ranging between both values. Analysis of consistently organized long-term demographic data has enhanced our understanding of Little Owl population dynamics. Further, this demographic data has been linked to specific habitat conditions at the nest site, home range and landscape scales. We offer clarification of the terminology related to nesting success and reproduction due to its importance in providing an accurate and consistent foundation for the data that will be used to assess the reproductive performance of the owls, as well in long-term monitoring of status and trends.

The Little Owl has a generalist diet and takes a high diversity of small prey. It eats a range of small-sized prey across its entire distribution area. The diet varies with the season and the geographical area. From north to south and from winter to summer, an increase in the numbers of insects in the diet has been observed. However, small mammals remain the key prey category by biomass and energetic yield, contributing significantly to the ecology and welfare of the species. For insect-eating owl species it is difficult to get a true picture of its diet by only studying its pellets or prey remains in nestboxes, because they catch lots of prey, the remains of which are hard to find and identify in pellets. We present their relative proportion. In this chapter we look at this prey diversity through time and space, and focus on the hunting method of the owl, as well as caching behavior in larders. We offer a thorough review of the owl’s diet and individual prey species, with attention given to the importance of micromammals. Pellet contents are described in detail and comprehensive results of camera-observed breeding seasons are presented, principally stemming from our own research over 17 breeding seasons by camera observation in 2002-2020, totaling 34 916 prey items.

This chapter presents a brief overview of the status of and threats to the Little Owl. We then offer a conservation strategy for the owl that involves five critical success factors: Knowledge, Limiting Factors, Evolution of Landscape Conditions, Legislation and Policies, and People. Thereafter, we describe four main drivers to implement this strategy, focused on Monitoring, Management, Standardized Methodologies and Data Management. The long-term conservation of the Little Owl is complicated, as the species is largely linked to an agriculturally dominated landscape. This landscape condition can change rapidly and significantly due to human demographics, and changes in policies and management. The conservation strategy described in this chapter requires a multiscale, multidisciplinary approach, with collaboration between different stakeholders (conservationists, scientists, different authorities, farmers) and additional research into the ecology of the species. This strategy must be applied at different levels: local, regional, national and international. We encourage people involved in this conservation strategy to work broadly, openly and to freely co-ordinate on issues, data, and management efforts that will benefit the broader array of species and environments of which the Little Owl is a part.

This chapter deals with research priorities that were obtained during the writing of this book. We first illustrate the recent insights that were published since the publication of the first volume. New research topics deal with further exploring and identifying critical habitat components and the effect of land improvement initiatives. Demographics need to be studied in less covered areas using methods that have been perfectioned in the typical highly researched countries. Examining responses of Little Owl populations to land uses and the effects of abiotic environmental factors should allow for more quantitative management and follow-up on the effectiveness of taken measures. The adoption of the information-theoretic approach, focus on process variation and searching for mechanisms will need more statistical background and thoroughness, leading to even more long-term observational studies and focus on the cumulative effects. To do this in an optimal way, more experiments are urgently needed, to enable controling for certain parameters. Finally there is a need for the expansion of the investigated geographic range and an increase in research and experiment maturity in emerging countries, hopefully enabled by highly mature research teams and international co-operation.

With its large distributional range across Europe, the Middle East, and Asia, and an ability to co-exist as a commensal with many human habitations, not surprisingly, the Little Owl has figured prominently in many cultural beliefs, and in a variety of ways. The common names given to this species across the countries are linked to its activity, to its voice, to its morphology, to its food, to beliefs, to its habitat, and to mythology. In Greek mythology, Athena was the daughter of Zeus and originally a Mycenaean palace goddess, guardian of cities, war goddess, patroness of arts and crafts, and promoter of wisdom. A particularly interesting example of the cultural use of Little Owls comes from Crespina, Italy, which was a center for the rearing of owls in captivity to be used for hunting small passerines. They were sold at the Little Owl market while tied up on a roost. The nobility (upper-class people) commonly hunted in the countryside using the Little Owls as bait. The history and traditions of the Little Owl are truly long, rich and varied, and grow with additional recoveries of artefacts from archaeological sites, as well as evolving cultural views. In closing this chapter, we urge reviewers of owl myths, traditions and lore to closely scrutinize the information they assemble, to determine whether the ideas and symbolism described in text and artefacts still apply in contemporary societies, or whether they are part of the colorful but quaint past.

In this chapter, we examine aspects of distribution and population in the Little Owl for its global range which covers 78 countries. Recent publications give an overview of population numbers and short- and long-term breeding population and breeding distribution trends for the EU28 and for continental Europe. The European Union (EU28) Red List assessments are based principally on the official data reported by EU Member States to the European Commission under Article 12 of the Birds Directive. In addition, population status and trends are assessed at the EU level. Data outside the European continent are obtained from individual publications. In very general terms, all cumulative data suggests that the global distribution of the Little Owl has increased in 12 countries, decreased in 10, remained unchanged in 25 or was insufficient for determination in 31 countries. For population numbers, the data suggests that the number of owls increased in 12 countries, decreased in 10, remained unchanged in 23 or was insufficient for determination in 33 countries. The global distribution and some limiting factors like latitude and elevation, are mapped, as well as European population numbers and short- and long-term trends. For each country we focus on the population estimates for currently existing populations and present distribution maps when available.

In this chapter we review the parameters that are of importance for the species, its prey species and its predators. The favored habitat for the Little Owl varies from the natural landscapes of steppe and arid deserts to anthropogenic areas. The common features are open areas with low grass, perches and cavities in the ground, rocks, trees or buildings. The species avoids forests, fallow land and large parcels of arable land. A mosaic effect seems to be important for the species, due to the use of habitat edges, in particular for the richness in prey found there. The relations between the landscape factors will determine local owl densities and demographics. All quantitative studies available were done on anthropogenic habitats. Of natural habitats, only qualitative descriptions were available. We first discuss natural habitats in general terms, then we give an overview of different types of occupied anthropogenic habitats, followed by the actual preference of the species toward certain habitat parameters. The latter studies entail both occupied and unoccupied habitats, while habitat typology studies consider only occupied habitats.

Different owl species and subspecies were defined in the early days of taxonomy uniquely based upon morphological features like size and color in specific geographical regions across the world. Recently, more differentiators are taken into account to define new species to avoid upgrading them from a subspecies based upon limited aspects. We consider the biological species concept that takes biological characteristics into account, morphological concept studies, especially morphometrics and coloration of the bird, the phylogenetic concept, using mitochondrial DNA studies to establish a lineage that eventually leads to a common ancestor, complemented by fossil evidence for the evolution of species. Vocalizations of Little Owls across the range are increasingly documented and taken into account as well. The last approach considers the geographical distribution and the use of validated, geocoded, high-quality photographic input. In this chapter we present the current fossil evidence for ancestors of the species. We describe the historical context in which subspecies have been defined. We illustrate the way the subspecies were described, for which we now have evidence for their relevance. We consider 14 subspecies of Little Owl for which we have found substantial evidence. This means that we have one more subspecies.