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Understanding of ecosystem structure and functioning requires detailed knowledge about plant–animal interactions, especially when keystone species are involved. The recent consideration of parrots as legitimate seed dispersers has widened the range of mechanisms influencing the lifecycle of many plant species. We examined the interactions between the burrowing parro tCyanoliseus patagonus and two dominant algarrobo trees (Prosopis alba and Prosopis nigra) in the Monte Desert, Argentina. We recorded the abundance and foraging behaviour of parrots; quantified the handling, consumption, wasting, and dispersal of ripe and unripe pods; and tested the viability of soft and hardripe seeds wasted and transported by parrots. We found a high abundance of burrowing parrots.They predated on soft seeds from unripe pods while exclusively feeding upon pulp wrapping hardseeds from ripe pods. Frequent pod wasting beneath the plant or transport at a distance invariablyimplied the dispersal of multiple seeds in each event. Moreover, soft seeds retained viability afterdesiccation outside the mother plant, suggesting effective seed dispersal after partial pod predation due to a predator satiation effect. In about half of the foraging flocks, at least one parrot departed in flight with pods in its beak, with 10–34% of the flock components moving pods at distances averaging 238 m (P. alba) and 418 m (P. nigra). A snapshot sampling of faeces from livestock and wildmammals suggested a low frequency of seed dispersal by endozoochory and secondary dispersalby ants and dung beetles. The nomadic movements and long flights of burrowing parrots betweenbreeding and foraging sites can lead to the dispersal of huge amounts of seeds across large areas thatare sequentially exploited. Further research should evaluate the role of the burrowing parrot as afunctionally unique species in the structure of the Monte Desert woods and the genetic structure ofalgarrobo species., This research was funded by the Loro Parque Fundación (grant reference: PP-146-2018-1).

[Aims]: Seed dispersal by endozoochory is an important process in plant regeneration and the establishment of new populations. Seeds with dormancy may especially benefit after disperser gut passage. However, the ways in which gut passage affect the germination of plant species with physiological dormancy remain unclear. Here, we experimentally assessed the mutualistic interaction between the Austral parakeet (Enicognathus ferrugineus) as a disperser of calafate (Berberis microphylla), a thorny bush inhabiting the understory of the Austral temperate forests of South America with seeds that are characterized by deep physiological dormancy., [Methods]: Germination success and viability of calafate seeds obtained from faeces and from intact fruits were tested under four treatments: (i) digested seeds, (ii) digested seeds with faecal extract, (iii) intact seeds from fruit and (iv) intact seeds from fruit with pulp., [Important]: Findings About 65% of the Austral parakeet droppings contained calafate seeds. Viability of seeds did not differ between treatments. However, germination was significantly higher in digested seeds than in intact seeds from fruits, while no difference was found between faecal and pulp extracts. Neither faecal matter nor fruit pulp provided seeds with any ecological advantages derived from enhancing germinability, but did confer some disadvantage in germination time. Faecal matter is expected to be completely lacking around seeds after several months under snow before germinating in the following spring, given intense washing due to persistent rain and the spring thaw in the Patagonian Andes. The higher germinability along with faster germination of digested seeds supports the hypothesis of a legitimate mutualistic interaction between Austral parakeets and calafate. We hypothesized that the passage through the disperser digestive tract might break physiological dormancy as differences in germinability between ingested and non-ingested seeds. Our results highlight the relevant role of endozoochory in plant species with physiological dormancy living in highly seasonal environments., K.S. and S.A.L. were funded by the projects PICT 2015-2072 and PICT 2018-1623.

Establishing whether herb seed endozoochory is accidental or has evolved independently or in combi-nation with other dispersal mechanisms may be valuable in the study of plant–animal interactions, but it remains unexplored for birds. We tested whether an Australian cockatoo, the galah (Eolophus roseicapilla), swallows entire seeds when feeding on other tissues without subsequent seed digestion, thus enhancing seed dispersal (the ‘foliage is the fruit’ hypothesis). Our preliminary sampling provides strong evidence supporting that this seed predator also acts as a legitimate endozoochorous disperser. A large proportion of droppings contained numerous seeds of six herb species of three plant families, surviving gut passage to be dispersed as viable propagules. The wide range in the number of seeds found in combinations with up to five species in particular droppings suggests both simultaneous and sequential passive ingestion without seed digestion and/or focused seed predation and digestion. As expected for inadvertent ingestion and inefficient digestion, our findings suggest that seed number and richness of dispersed plants are associated traits in this particular mutualistic interaction. This relationship can have important implications in community-wide processes, favouring herbs whose seeds are disseminated in a viable state over those predated or negatively affected by gut transit., We thank J. Griffith and the owners of Artemis Station for help in the fieldwork and Fundacion Repsol for funding. Adam Lovas-Kiss was supported by the Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences and by the New National Excellence Programme of the Ministry of Human Capacities (UNKP-19-4-DE-172).

How animals use food resources according to their relative availability is essential for our understanding and predictions of ecosystem interaction. Non-linear functions between use and availability are described with the feeding functional response, a key tool to describe such functions that is still poorly understood in some cases. For example, in species with a marked sexual size dimorphism it is not clear how such non-linear functions differ between males and females. Here, we used likelihood methods and model selection to model non-linear functions in legume use by male and female great bustards (Otis tarda) based on diet composition data from droppings. The great bustard shows the highest sexual size dimorphism among birds, and it has opportunistic and generalist foraging habits, with a strong selection for legumes. Simple functional-response models described the proportion of legumes in great bustard droppings as a non-linear function of legume availability. Functional response type II fitted to data better than type III in autumn and winter, whereas in spring, type III was the best-fitted model, describing a dietary switch of great bustards feeding on legumes. The best-fitted functional response included an effect of sex in the asymptote of the curve; the female diet included a higher proportion of legumes than the male diet, suggesting a possible effect of sexual size dimorphism. We concluded that great bustards behaved as opportunistic foragers, whose sexual size dimorphism might play a role in the functional response to legumes., This study was supported by the Spanish Administration (grant numbers CGL2005-04893, CGL2008-02567, CGL2012-36345 and CGL2017-87206-P; AEI/FEDER, UE) and HENARSA-CSIC contract. The first author would like to thank Spanish SEPE from Spanish Ministry of Labour and Social Insurance for its funding support.

Intra-specific coloration polymorphism coupled with an ancient process of lineage differentiation in Berberomeloe majalis (Linnaeus, 1758) offers the opportunity to analyse the temporal scenario in which the correlation between toxicity and coloration might have evolved. Based on phylogenetic and phylogeographic analyses, we identified the timing for the split between red-striped and entirely black morphotypes of B. majalis. To evaluate whether coloration patterns and toxicity are related in this species, we quantified the concentration of cantharidin across morphotypes and phylogeographic lineages. Phylogenetic analyses based on cox1 mitochondrial DNA sequences recovered three major clades where both morphotypes were intermingled, indicating a multiple homoplastic origin for the entirely black coloration. Our analyses showed that cantharidin content did not differ between morphs of B. majalis; however, it significantly increased in haemolymph in females kept isolated from males, which reveals the females’ ability either to concentrate cantharidin towards haemolymph or to synthesize cantharidin themselves. Lack of monophyly and absence of genetic isolation in both morphotypes favour the hypothesis of a recent homoplastic phenomenon to explain the loss of the striped pattern. Our phylogenetic and phylogeographic analyses show that changes in coloration are recent, suggesting that the ancient pressures that fixed and maintained red-striped colorations are no longer acting today on B. majalis. The absence of change in cantharidin content (i.e. entirely black and red-striped specimens are equally poisonous) suggests that the evolution of colour polymorphisms in B. majalis is probably decoupled from toxicity., CGL2010-15786, CGL2008-02567, CGL2012-36345, y CGL2015-66571-P

[EN]: In sexually size-dimorphic species, physiological constraints derived from differences in body size may determine different food requirements and thus a trophic niche divergence between males and females. These relationships between sexual size dimorphism (SSD) and dietary overlap are not well understood in birds. We analyzed differences between the sexes in diet composition, dietary diversity, diet selection, and volume and density of droppings, as well as the dietary overlap between sexes, in the Great Bustard (Otis tarda), the species showing the highest SSD among birds. We discuss the differences that we found in relation to various predictions derived from ecological and physiological differences between the sexes, under the hypothesis that these differences are ultimately determined by the strong SSD of this species. As expected, our best linear mixed-effects food selection models included sex as a main factor explaining differences in diet composition and dietary diversity of Great Bustards throughout the annual cycle. Both sexes were mostly herbivorous, consuming legumes when they were available. Males consumed fewer arthropods, but of significantly larger size, than females. The droppings of males were larger, heavier, and slightly denser than those of females. Males showed higher dietary diversity than females, except during the postmating season. The mean dietary overlap between the sexes was 0.7, one of the smallest values among birds. Overall, our results suggest that the species' extreme SSD along with the distinct reproductive role of each sex might explain the trophic niche divergence in the Great Bustard., [ES]: En las especies con dimorfismo sexual de tamaño, las limitaciones fisiológicas derivadas de las diferencias en el tamaño corporal pueden determinar diferentes requerimientos alimentarios y por ende una divergencia del nicho trófico entre los machos y las hembras. Estas relaciones entre el dimorfismo sexual de tamaño corporal (DST) y el solapamiento de la dieta no están bien entendidas en las aves. Analizamos las diferencias sexuales en la composición de la dieta, la diversidad de la dieta, la selección de la dieta, y el volumen y la densidad de las heces, así como el solapamiento de la dieta entre sexos en Otis tarda, la especie con mayor DST entre las aves. Las diferencias encontradas fueron analizadas con relación a varias predicciones derivadas de las diferencias ecológicas y fisiológicas entre los sexos, bajo la hipótesis de que estas diferencias están determinadas en última instancia por el fuerte DST en esta especie. Como esperábamos, nuestros mejores modelos lineales de efectos mixtos de selección de alimentos incluyeron al sexo como el factor principal que explica las diferencias en la composición y en la diversidad de la dieta en O. tarda a lo largo del ciclo anual. Ambos sexos fueron principalmente herbívoros, consumiendo legumbres cuando estaban disponibles. Los machos consumieron menos artrópodos pero de tamaño significativamente más grande que las hembras. Las heces de los machos fueron de mayor tamaño y más pesadas, y levemente más densas que las de las hembras. Los machos mostraron una mayor diversidad en la dieta que las hembras, excepto durante la estación post reproductiva. El solapamiento promedio de la dieta entre los sexos fue 0.7, uno de los valores más pequeños entre las aves. En conjunto, nuestros resultados sugieren que el enorme DST en esta especie, junto con el rol reproductivo distintivo de cada sexo, podrían explicar la divergencia del nicho trófico en O. tarda., This study was financially supported by the Spanish Ministry of Science and Innovation and the Spanish Ministry of Economy and Competitiveness through projects CGL2005-04893, CGL2008-02567, and CGL2012- 36345. N

Studies evaluating agri-environmental schemes (AES) usually focus on responses of single species or functional groups. Analyses are generally based on simple habitat measurements but ignore food availability and other important factors. This can limit our understanding of the ultimate causes determining the reactions of birds to AES. We investigated these issues in detail and throughout the main seasons of a bird's annual cycle (mating, postfledging and wintering) in a dry cereal farmland in a Special Protection Area for farmland birds in central Spain. First, we modeled four bird response parameters (abundance, species richness, diversity and "Species of European Conservation Concern" [SPEC]-score), using detailed food availability and vegetation structure measurements (food models). Second, we fitted new models, built using only substrate composition variables (habitat models). Whereas habitat models revealed that both, fields included and not included in the AES benefited birds, food models went a step further and included seed and arthropod biomass as important predictors, respectively, in winter and during the postfledging season. The validation process showed that food models were on average 13% better (up to 20% in some variables) in predicting bird responses. However, the cost of obtaining data for food models was five times higher than for habitat models. This novel approach highlighted the importance of food availability-related causal processes involved in bird responses to AES, which remained undetected when using conventional substrate composition assessment models. Despite their higher costs, measurements of food availability add important details to interpret the reactions of the bird community to AES interventions and thus facilitate evaluating the real efficiency of AES programs.

Despite the fact that parrots (Psitacifformes) are generalist apex frugivores, they have largely been considered plant antagonists and thus neglected as seed dispersers of their food plants. Internal dispersal was investigated by searching for seeds in faeces opportunistically collected at communal roosts, foraging sites and nests of eleven parrot species in different habitats and biomes in the Neotropics. Multiple intact seeds of seven plant species of five families were found in a variable proportion of faeces from four parrot species. The mean number of seeds of each plant species per dropping ranged between one and about sixty, with a maximum of almost five hundred seeds from the cacti Pilosocereus pachycladus in a single dropping of Lear's Macaw (Anodorhynchus leari). All seeds retrieved were small (

Predictive species' distribution models may answer ecological questions about habitat selection, co-occurrence of species and competition between them. We studied the habitat preferences and segregation of two sympatric species of declining sandgrouse, the black-bellied sandgrouse (Pterocles orientalis) and the pin-tailed sandgrouse (Pterocles alchata), during the breeding season. We developed predictive models that related sandgrouse presence to environmental variables at three different spatial levels: large geographical, landscape and microhabitat scales. At the large geographical scale, differences between sandgrouse distributions, in the Iberian Peninsula, seem to be explained mainly in terms of bioclimatology: pin-tailed sandgrouse appear to be a more thermophilous species and occupy warmer sites usually located in flatter areas. At the landscape spatial level, in those areas that exhibit environmental conditions allowing for both species' co-existence at a large geographical scale, black-bellied sandgrouse appear to be more tolerant to environmental variation than pin-tailed sandgrouse. At the microhabitat level, however, differences between species could be related to different flocking behaviour as a consequence of different sensitivities to vegetation structure and predators. Thus, the observed spatial distribution patterns are the result of different ecological factors that operate at different spatial levels. Conservation guidelines for these species should therefore consider their habitat preferences at large geographical, landscape and microhabitat scales. © 2014 Springer-Verlag Berlin Heidelberg.

9 paginas, 2 figuras, 6 tables y 4 appendix, Organic farming is considered an important way to preserve biodiversity in agricultural landscapes. However, more work is still necessary to enable a full appraisal of the potential benefits of this way of farming, since studies differ in the evaluation of its effectiveness. Studies are particularly scarce in the Mediterranean region, where different climatic and ecological conditions prevent simple extrapolations from work carried out at northern latitudes. In the present study, an analysis of weed and arthropod communities was conducted in 28 pairs of organic and conventional fields in a dry cereal farmland in central Spain. Plants were identified to the species level, and arthropods to the family level. Pitfalls and sweep nets were used to sample respectively, ground-dwelling and plant-visiting arthropods. Abundance (total numbers of individuals), richness (total numbers of plant species or arthropod families), diversity (Shannon–Wiener index) and biomass (milligrams per pitfall/sweep-net) were calculated for each field and compared between organic and conventional fields using Generalized Linear Mixed Models (GLMMs). To explore the effect of predictor variables on weed richness and arthropod biomass, GLMMs were used. Organic fields showed higher abundance of weeds and arthropods (3.01 and 1.43 times, respectively), higher weed richness and diversity (2.76 and 2.33 times, respectively), and a 24% reduction in cereal plants. Arthropod diversity was lower in organic fields due to the presence of three dominant groups: Collembola, Chloropidae (Diptera), and Aphididae (Hemiptera). Weed richness increased as cereal cover decreased in organic fields. Total arthropod biomass was slightly higher in organic fields, and was affected by weed abundance and diversity. The differences between organic and conventional fields found in this study were higher than those reported for northern latitudes. This could be explained by the richer weed flora in the Mediterranean region, and a higher weed seed availability favored by the two-year rotation system typical of Iberian dry cereal farmland. We conclude that organic farming may contribute to preserve biodiversity in dryland cereal agroecosystems in the Mediterranean region, Additional funding was provided by projects CGL2005-04893 and CGL2008-02567 of the Dirección General de Investigación of the Spanish Ministry for Science and Innovation.

Foraging strategies and diet selection play an essential role in individual survival and reproductive success. The study of feeding ecology becomes crucial when it concerns endangered species such as the Little Bustard (Tetrax tetrax), whose populations are suffering strong declines as a consequence of agricultural intensification. Despite the fact that several populations are overwintering in areas affected by agricultural transformation, nothing is known about how feeding behavior responds to these changes. We studied for the first time the winter diet composition of the Little Bustard in Spain and compared it between areas with two different farming systems: dry and irrigated farmland. Diet was studied through the micro-histological analysis of 357 droppings collected in 16 locations across the wintering range of the Little Bustard in Spain. Up to 62 plant species were identified. Most consumed species were cultivated legumes (46.7%) and dicotyledon weeds (45.6%), while monocotyledons were scarcely consumed (7.7%). Diet composition differed significantly between dry and irrigated farmland areas. In irrigated areas, diet was mainly composed of legumes, in particular alfalfa (Medicago sativa). In contrast, in dry farmland areas diet was more diverse, composed mainly of weeds (Compositae, Papaveraceae, and Cruciferae) and also cultivated legumes, particularly vetch (Vicia sativa). These results suggest that legume crops could be an effective measure to improve habitat quality in areas with scarce food resources. However, in the case of irrigated areas, the strong reliance on alfalfa could make the Little Bustard more vulnerable to changes in land use. This study is the first step to understand the winter trophic requirements of the endangered Little Bustard, but further research is necessary to understand the food requirements of this species during the entire annual cycle.