Assessing the ability of novel ecosystems to support animal wildlife through analysis of diurnal raptor territoriality

Novel ecosystems have emerged through human intervention and are rapidly expandingaround the world. Whether they can support animal wildlife has generated considerable controversy.Here we developed a new approach to evaluate the ability of a novel forest ecosystem,dominated by the exotic tree species Eucalyptus globulus, to support animal wildlife inthe medium and long term. To evaluate this ability, we took advantage of the fact that speciesterritory size decreases with increasing habitat quality, and we used territoriality of araptor guild composed of Northern Goshawk (Accipiter gentilis), Eurasian Sparrowhawk(A. nisus) and Common Buzzard (Buteo buteo) as indicator. We compared the territorialityof these species in the novel ecosystem with that in other ecosystems found in the literature.Average distances between con-specifics in the novel ecosystem were similar, or evenshorter, than those in other ecosystems. Average distances between Goshawk con-specificswere among the shortest described in the literature. All three species nested preferably in mixed stands abundant in large exotic trees, with high structural complexity and abundance of native species within the stand. Key factors supporting this diverse and dense raptor community were the special forest management system implemented in the study area and the agricultural matrix located close to forest plantations that complements the supply of prey. Our results suggest that forest management that promotes a complex and suitable forest structure can increase the ability of novel forest ecosystems to support wildlife biodiversity, particularly a diverse nesting community of forest-dwelling raptors and their preys. The results further suggest the suitability of territoriality for assessing this potential of novel ecosystemsMinisterio de Ciencia y TecnologíaUniversidad de AlcaláMinisterio de Educación y Cienci

Higher reproductive success of small males and greater recruitment of large females could explain the strong reversed sexual dimorphism (RSD) in the northern goshawk

Abstract Reversed sexual dimorphism (RSD), whichoccurs when the female of a species is larger than the male,is the rule for most birds of prey but the exception amongother bird and mammal species. The selective pressuresthat favour RSD are an intriguing issue in animal ecology.Despite the large number of hypotheses proposed to explainthe evolution of RSD, there is still no consensus about themechanisms involved and whether they act on one or bothsexes, mainly because few intrapopulation studies havebeen undertaken and few raptor species have been investigated.Using the strongly size-dimorphic northern goshawk(Accipiter gentilis L.) as a model, we studied a populationwith one of the highest densities of breeding pairs reportedin the literature in order to understand selective pressuresthat may favour RSD. We evaluated life-history processes,including recruitment of adult breeders and reproductivesuccess, and we explored the mechanisms thought to act oneach sex, including hunting efficiency, diet, body conditionand mate choice. We found that smaller males producedmore fledglings than larger ones, but there was no relationshipbetween size and reproductive success for femalesMinisterio de Educación y Cienci

Anything for a quiet life: shelter from mobbers drives reproductive success in a top-level avian predator

17 p.Understanding how habitat structure relates to reproductive performance of species can help identify what habitats are of the highest quality for a given species and thereby guide effective management. Here, we compared the influence of prey abundance and the amount of shelter area on the relationship between habitat and breeding performance. We focused on the forest-dwelling northern goshawk Accipiter gentilis in an agroforestry system. Using structural equation modelling, we tested the associations between reproductive performance and three explanatory factors: habitat structure, abundance of food resources or levels of mobbing disturbance, and prey supply to the nest. Our results suggest that habitat structure influences reproductive performance through shelter rather than through prey abundance. During the study period, forested habitats in the breeding territories provided shelter to the goshawk, reducing disturbance by carrion crows Corvus corone, which acted as large, aggressive, social mobbers. Decreased disturbance increased prey supply to the nest, probably because it favored food accessibility and male goshawk foraging efficiency. Habitat was not significantly associated with quality of the breeders, both in terms of body size and seniority in the territories. Our findings suggest that reproductive performance, and therefore habitat quality, may depend more on sheltered access to food resources than on the amount of food available. Our observation that mobbers decrease predator foraging efficiency highlights the possibility of designing effective, socially acceptable predator management strategies to protect sensitive domestic prey.Ministerio para la Transición Ecológica y el Reto DemográficoMinisterio de Educación y CienciaMinisterio de Ciencia e InnovaciónComunidad de MadridUniversidad de Alcal

Territoriality in diurnal raptors: relative roles of recent evolution, diet and nest site

Animal territoriality, defined here as defence of well-delimited breeding areas to exclude competitors, has beenwidely studied. However, the phylogenetic and ecological characteristics influencing the variation in the expressionof this behaviour are poorly understood. We evaluated the effect of phylogeny and key ecological factors on territorialbehaviour and territory size in diurnal raptors from the western Palearctic and New World. To our knowledge, ourwork is the first comparative analysis of raptor territorial behaviour and territory size that accounts for phylogeneticrelationships. One important finding is that territorial behaviour has not been strongly conserved across evolutionarytime, but differences in territoriality of diurnal raptors have been influenced by recent evolution, which has ledto variations of this behaviour in response to changes in climate and habitat. Raptor current ecology is also associatedwith the expression of these traits. Species that capture more agile prey and nest in more protected sites weremost likely to be territorial. Additionally, territorial species that are bigger and capture more agile and bigger preydefended larger territories than species feeding on more vulnerable and smaller prey. We discuss potential mechanismsfor these patterns and the implications of our findings for future research on avian territoriality.Comisión Interministerial de Ciencia y Tecnología-CICYTREMEDINALMinisterio de Educación y Cienci

Spatial relationships and mechanisms of coexistence between dominant and subordinate top predators

Most forest ecosystems contain a diverse community of top-level predators. How these predator species interact, and howtheir interactions infl uence their spatial distribution is still poorly understood.Here we studied interactions among top predators in a guild of diurnal forest raptors in order to test the hypothesisthat predation among competing predators (intraguild predation) signifi cantly aff ects the spatial distribution of predatorspecies, causing subordinate species to nest farther away from the dominant ones.Th e study analyzed a guild in southwestern Europe comprising three raptor species. For 8 years we studied the spatialdistribution of used nests, breeding phenology, intraguild predation, territory occupancy, and nest-builder species andsubsequent nest-user species.Th e subordinate species (sparrowhawk Accipiter nisus ) nested farther away from the dominant species (goshawk A. gentilis), which preyed on sparrowhawks but not on buzzards Buteo buteo , and closer to buzzards, with which sparrowhawks donot share many common prey. Th is presumably refl ects an eff ort to seek protection from goshawks. Th is potential positiveeff ect of buzzards on sparrowhawks may be reciprocal, because buzzards benefi t from old sparrowhawk nests, which buzzardsused as a base for their nests, and from used sparrowhawk nests, from which buzzards stole prey. Buzzards occasionallyoccupied old goshawk nests.Universidad de Alcalá de Henare

Prey preferences and recent changes in diet of a breeding population of the Northern Goshawk Accipiter gentilis in Southwestern Europe

Capsule: Northern Goshawk Accipiter gentilis diet has changed significantly since the 1980s,probably due to changes in populations of preferred prey species.Aims and methods: To assess changes to the breeding season diet of the Northern Goshawk insouthwest Europe over three decades. We examined prey remains at and around nests andassessed avian prey availability using point count surveys.Results: During 2008&#-11, Goshawks mainly ate birds, with Feral Pigeons Columba livia f. domesticabeing the most important prey species. Goshawks preferred prey of 100&;8722#400 g and forest preyspecies to non-forest species. Goshawk diet has changed significantly over recent decades: 22%of current prey items belong to species that were not part of the diet in the 1980s. We suggestthat these dietary changes reflect changes in the abundance of prey species of the preferredsize caused by changes in land use leading to an increase in forest cover, new prey speciescolonization and changes in the abundance and management of domestic prey.Conclusion: This study emphasizes that major transformations occurring in agroforestry systemsare affecting the main preferred prey of important forest predators, which may haveconsequences for conservation of both the predators and their prey

Effective nut dispersal by magpies (Pica pica L.) in a Mediterranean agroecosystem

Scatter-hoarding animals such as corvids play a crucial role in the dispersal of nut-producing tree species. This interaction is well known for some corvids, but remains elusive for other species such as the magpie (Pica pica), an abundant corvid in agroecosystems and open landscapes of the Palearctic region. In addition, the establishment of the individual dispersed seeds—a prerequisite for determining seed-dispersal effectiveness—has never before been documented for the interaction between corvids and nut-producing trees. We analyzed walnut dispersal by magpies in an agroecosystem in southern Spain. We used several complementary approaches, including video recording nut removal from feeders, measuring dispersal distance using radio tracking (with radio transmitters placed inside nuts), and monitoring the fate of dispersed nuts to the time of seedling emergence. Magpies were shown to be highly active nut dispersers. The dispersal distance averaged 39.6 ± 4.5 m and ranged from 4.1 to 158.5 m. Some 90% of the removed walnuts were cached later, and most of these (98%) were buried in the soil or hidden under plant material. By the time of seedling emergence, ca. 33% of nuts remained at the caching location. Finally, 12% of the cached nuts germinated and 4% yielded an emerged seedling, facilitating the transition to the next regeneration stage. The results demonstrate for the first time that magpies can be an effective scatter-hoarding disperser of a nut-producing tree species, suggesting that this bird species may play a key role in the regeneration and expansion of broadleaf forests in Eurasia.Gobierno de EspañaComunidad de MadridMinisterio de Economía y Competitivida

Breeding habitat preferences and reproductive success of Northern Goshawk (Accipiter gentilis) in exotic Eucalyptus plantations in southwestern Europe

With ongoing degradation of natural forests and spread of forest plantations, plantations must play an increasinglyimportant role in biodiversity conservation. Study of habitat selection and reproductive success ofsurrogate species in plantations can guide forest management decisions for increasing biodiversity. In this paperwe studied the suitability of exotic Eucalyptus plantations managed at low intensity in northwestern Spain asbreeding habitat for Northern Goshawk (Accipiter gentilis), a top predator frequently considered a surrogatespecies in conservation.Goshawks showed high breeding density, high reproductive success and a regular spatial distribution ofnesting territories. Territoriality was the most important determinant of habitat selection. Goshawks selectedextra-mature Eucalyptus trees in areas of high structural complexity (high tree density, tree species richness, andnumber of tree strata) in the most heterogeneous forest stands (old-mixed Eucalyptus). Reproductive successdecreased with increasing local density of breeding pairs, but reproductive success was not related to structuralcharacteristics of nest stands.The studied plantations provided a suitable breeding habitat for Goshawks. The birds preferred to nest inlarge Eucalyptus trees with appropriate structure in their immediate surroundings. The strong preference ofGoshawks for structurally mature forest patches may make them useful as a surrogate species for assessing theability of forest management practices to promote overall biodiversity in exotic Eucalyptus plantations exploited at low intensity.Comisión Interministerial de Ciencia y Tecnología-CICYTMinisterio de Educación y CienciaMinisterio de Economía y CompetitividadREMEDINALUniversidad de Alcal

Massive and effective acorn dispersal into agroforestry systems byan overlooked vector, the Eurasian magpie (Pica pica)

Oak regeneration and the expansion of forested sites in Eurasia rely on acorn dispersal by animals,especially the Eurasian jay (Garrulus glandarius). However, in open agroforestry systems where jaysare absent, such as old fields far from acorn sources, oak recruitment still occurs. We hypothesize that theEurasian magpie (Pica pica), an abundant corvid in this system, substitutes the jay in its seed dispersal function.By ringing 169 magpies, video recording >7500 acorn removal events with trail cameras, and radiotagging337 acorns, we quantified that (1) magpies cached 41&#-56% of the annual acorn production of Quercusilex trees in single caches on the ground; (2) breeding pairs, and especially males, were the main acorndispersers; (3) each breeding magpie cached 169&#-1372 acorns in 6 weeks; and (4) the effectiveness of dispersal(percentage of cached acorns resulting in seedlings) was 0.6&-2.4%, which (5) yielded a high densityof emerged seedlings (56&-439 seedlings/ha). We evidence that magpie could be a key species in the regenerationof oak agroforestry mosaics because they massively and effectively dispersed acorns. However, inour particular study site, effectiveness was low probably due to herbivory and summer drought stress (i.e.,a context limitation rather than an intrinsic limitation of the disperser). As the distributions of magpies andoaks overlap widely in Eurasia, effective acorn dispersal by magpies could have a significant role in largescaleoak forest recovery in strongly fragmented landscapes.Ministerio de Ciencia y TecnologíaREMEDINALUniversidad de AlcaláMinisterio de Ciencia, Innovación y Universidade

Caching territoriality and site preferences by a scatter-hoarder drive the spatial pattern of seed dispersal and affect seedling emergence

1. For plants with seeds dispersed by scatter-hoarders, decision-making by animals when caching determines the spatial pattern of seed dispersal and lays the initial template for recruitment, driving the regeneration of many species. However, the mechanism by which animal behaviour shapes seed distributions in spatially complex landscapes is not well understood. We investigated caching territoriality and site preferences to determine the spatial pattern of seed caching at different scales and whether scatter-hoarding behaviour drives the spatial distribution of seedling emergence. 2. We used radio-tracking and automatic wildlife cameras to monitor holm oak (Quercus ilex) acorn caching by Eurasian magpies (Pica pica), who are effective scatter-hoarders in agroforestry systems. We assessed the effect of caching territories, distance to seed source, habitat, subhabitat, microsites, and caching material in the spatial pattern of acorn dispersal by magpies. In addition, we analysed the relationship between the density of cached acorns and of emerged seedlings in different habitats. 3. Breeding magpies cached the acorns inside their caching territories, where they preferred tilled areas over oak plantations and mostly avoided old fields. These differences in habitat preference were maximized at relatively short to medium dispersal distances, where most acorns were cached, and decreased or disappeared at long-distances. Within tree plantations, magpies preferred high plant-productivity sites over low productivity ones. At the finest spatial scale, magpies preferred structures built by animals, such as rabbit grit mounds and latrines and ant litter mounds, to cache the acorns. In many sites, magpies selected uncommon materials such as stones and litter to cover caches. In the subsequent spring, seedling emergence was positively correlated with acorn cache density. 4. Synthesis. Scatter-hoarding is a hierarchical process in which caching sites are selected using different criteria at different spatial scales driven by territoriality and site preferences. Territoriality constrained dispersal distance and the habitats available for acorn caching. Magpie territoriality therefore indirectly drives oak seedling emergence and can determine oak recruitment and forest regeneration.CGL2014-459 53308-P (Ministerio Ciencia y Tecnología) PID2019-106806GB-I00 (Ministerio Ciencia e Innovación) S2013/MAE-2719 and S2018/EMT-4338 (Remedinal, CAM) CCG2014/BIO-02 & GP2019-6 (UAH) BES-2015-075276(FPI, MCT