Hedgerows interact with forests to shape the abundance of mesopredators and their predation rate on eggs in farmland landscapes.

Nest predation is the main cause of reproductive failure, particularly in ground-nesting birds on farmlands. Understanding the links between nest predation and habitat change can help design effective management schemes to constrain the negative impact of predation pressure on birds. However, the mechanisms underlying the relationships between landscape attributes, predator distribution, and nest predation are still unclear. Here, we use an experimental approach to examine the effects of distance to the hedgerow as well as hedgerow and forest densities on the abundance of major mesopredators of ground nests of our study area (i.e., corvids) and on the predation rate of artificial ground nests (n = 2576). We found evidence that landscape configuration influenced predation patterns differently depending on the predator species. Nest predation by corvids was more likely in homogeneous and open agricultural landscapes with a low density of forest and hedgerows, whereas predation by other predators was more likely close to hedgerows. Nest predation by corvids and the abundance of corvids also tended to be lower in landscapes dominated by grasslands. Other variables such as road density and distance to human settlements had contrasted effects on the likelihood of a nest being depredated by corvids, i.e., no effect with proximity to human settlements and decreasing trend with road density. Altogether, our results suggest that landscape features interact with mesopredator distribution and their predation rates of ground nests. Therefore, from a conservation and management perspective, a heterogeneous agricultural landscape that includes a mixture of crops associated with patches of forests, hedgerows, and grasslands offering alternative food to generalist predators should contribute to reducing ground-nesting bird predation.

Detectability and predator strategy affect egg depredation rates: Implications for mitigating nest depredation in farmlands.

Predation is a major evolutionary force in animal ecology. Mechanisms by which prey coloration provides camouflage has been widely studied. However, predator response to prey camouflage and concealment has received less attention. Understanding vegetation structure effect on depredation success could help managers design strategies to mitigate the depredation of managed species (e.g., threatened or hunted). We aimed to investigate the relationship between depredation rate, nest camouflage and concealment in ground-nesting birds of farmlands, and their predators. We set up an experiment of 2576 artificial ground nests to assess the role of egg coloration (white, light green, and dark green), egg size (small, medium, and large), and vegetation structure (vegetation height and land use) in nest survival rates. We also explored the role of predator searching strategies by analysing clumped depredation and multiple depredation events. Of the nests, 34.0% were depredated, with corvids as the predators 78.5% of the time. Corvid depredation decreased by 40-60% in grasslands and spring crops above a vegetation height of 30 cm. In contrast, vegetation height and land use may be of far less importance in avoiding depredation by other predators. The probability of depredation was spatially clumped, suggesting that predators increase search effort in areas where a nest was previously encountered. Neighboring depredation and depredation repetition were more frequent in corvids than in other predators. Our study indicates that nests in vegetation higher than 30 cm had a drastic reduction in depredation rates by corvids. Management of vegetation structure is a key tool to mitigate depredation risk, and improving the availability of alternative food resources may be a complementary tool.

Revisiting an old question: Which predators eat eggs of ground-nesting birds in farmland landscapes?

Nest predation is a major cause of reproductive failure in birds, but predator identity often remains unknown. Additionally, although corvids are considered major nest predators in farmland landscapes, whether breeders or floaters are involved remains contentious. In this study, we aimed to identify nest predators using artificial nests, and test whether territorial or non-breeders carrion crow (Corvus corone) and Eurasian magpie (Pica pica) were most likely involved. We set up an experiment with artificial ground nests (n = 1429) in farmland landscapes of western France, and assessed how different combinations of egg size and egg material (small plasticine egg, large plasticine egg, quail and natural hen eggs) might influence predation rates and predator species involved. Nest predators were identified using remotely triggered cameras and marks left in plasticine eggs. Corvids were by far the predators most involved (almost 80% of all predation events), independent of egg type. Carrion crows alone were involved in 60% of cases. Probability of predation increased with egg size, and predation rate was higher for natural than for artificial eggs, suggesting that, in addition to egg size, predators might perceive plasticine and natural eggs differently. Predation rates of artificial nests by corvids were related significantly to corvid abundance, and far more to breeder than floater abundances, for both carrion crows and magpies. This study emphasizes the importance of identifying predators at species level, and considering their social status when assessing corvid abundance impact on prey population dynamics. Combining camera traps and plasticine eggs can achieve this objective. Given the high predation rate by carrion crows, a better understanding of landscape-mediated changes in predator diet seems mandatory to design mitigation schemes able to confront ecological challenges raised by generalist predators.

Exposure of Wild Ungulates to the Usutu and Tick-Borne Encephalitis Viruses in France in 2009-2014: Evidence of Undetected Flavivirus Circulation a Decade Ago.

Abstract: Flaviviruses have become increasingly important pathogens in Europe over the past few decades. A better understanding of the spatiotemporal distribution of flaviviruses in France is needed to better define risk areas and to gain knowledge of the dynamics of virus transmission cycles. Serum samples from 1014 wild boar and 758 roe deer from 16 departments (administrative units) in France collected from 2009 to 2014 were screened for flavivirus antibodies using a competitive ELISA (cELISA) technique. Serum samples found to be positive or doubtful by cELISA were then tested for antibodies directed against West Nile virus (WNV), Usutu virus (USUV), Bagaza virus (BAGV), and tick-borne encephalitis/Louping ill viruses (TBEV/LIV) by microsphere immunoassays (except BAGV) and micro-neutralization tests. USUV antibodies were detected only in southeastern and southwestern areas. TBEV/LIV antibodies were detected in serum samples from eastern, southwestern and northern departments. The results indicate continuous circulation of USUV in southern France from 2009 to 2014, which was unnoticed by the French monitoring system for bird mortality. The findings also confirm wider distribution of TBEV in the eastern part of the country than of human clinical cases. However, further studies are needed to determine the tick-borne flavivirus responsible for the seroconversion in southwestern and northern France.

Influence of flavivirus co-circulation in serological diagnostics and surveillance: A model of study using West Nile, Usutu and Bagaza viruses.

This study aims at assessing the serological cross-reactions existing between three mosquito-borne flaviviruses with avian reservoirs co-circulating in Europe: West Nile (WNV), Usutu (USUV) and Bagaza (BAGV). The study is useful for a better interpretation of serological results in diagnostics and surveillance. Serum samples obtained from a natural host, the red-legged partridge (Alectoris rufa), experimentally infected with WNV, USUV or BAGV were analysed using two commercially available WNV competition ELISAs suitable for serological surveillance, and by the confirmatory virus neutralization test (VNT). The ELISAs examined showed different levels of specificity for WNV, as judged by cross-reaction observed with the other flaviviruses. By VNT, virus-specific antibodies were confirmed in 80%, 50% or 0% of sera from WNV-, BAGV-, or USUV-inoculated birds, respectively. The results indicate how the co-circulation of cross-reacting flaviviruses may affect the outcomes of WNV serological surveillance when applying currently available serological tools. On the one hand, the choice of the ELISA test for antibody screening should consider the differences found in specificity, since one test is more specific for WNV while the other one is more suitable for detection of a broader range of flavivirus antibodies. On the other hand, besides corroborating that cross-neutralization occurs between flaviviruses from different serocomplexes (WNV/USUV and BAGV), this study points out that cross-neutralization between WNV and USUV is not symmetric, and reveals the difficulty to identify USUV infections serologically. This finding indicates that actual USUV infections might be underestimated in the current diagnostic schemes.

Changes in habitat selection patterns of the gray partridge Perdix perdix in relation to agricultural landscape dynamics over the past two decades.

Changes in agricultural practices have reshaped agricultural landscapes and triggered a drastic decline in spatial and temporal heterogeneity leading to changes in habitat quality and food resources for birds. However, the precise relationships between landscape changes, spatial and temporal heterogeneity, and habitat preferences in response to those changes remain poorly known.We investigated patterns of habitat selection and causes for changes over the years 1997-2017 for the gray partridge Perdix perdix, an iconic farmland species which has experienced a severe decline since the 1950s. Using a long-term (1997-2017) dataset collected over 435 km2, we modeled relationships between annual land-cover maps and partridge sightings over 17 5-year moving windows, assessing the effects of landscape metrics, the strength of the relationships, and the dynamics of habitat suitability.We detected a shift in gray partridge habitat preferences over time, toward more risky habitats. Avoidance of predator reservoirs (woodlands and buildings) has weakened, and selection of human infrastructure, such as roads and tracks, has increased. Since 1997, the mean size of suitable patches has also decreased by about 26%.We have interpreted these changes in habitat selection as being the result of decreasing habitat quality and the increasing prevalence of captive-reared birds, currently released in their thousands in the study site. Synthesis and applications. The gray partridge has not adjusted well to changes in farming practices, and the low, still decreasing, population density suggests that it is not sustainable, despite local initiatives and the investment in captive-bird releases. We emphasize that efforts must be redirected toward habitat improvement to restore the density of refuge cover, insects, and seeds in the landscape, hunting management to ensure self-sustainable populations and massive releases of high-quality birds. Only integrated local management, involving hunters, farmers, gamekeepers, and scientists can ensure the recovery of this species.

Complete mitochondrial genome of the Western Capercaillie Tetrao urogallus (Phasianidae, Tetraoninae).

The Western Capercaillie (Tetrao urogallus) is a galliform bird of boreal climax forests from Scandinavia to eastern Siberia, with a fragmented population in southwestern Europe. We extracted the DNA of T. urogallus aquitanicus and obtained the complete mitochondrial genome (mitogenome) sequence by combining Illumina and Sanger sequencing sequence data. The mitochondrial genome of T. urogallus is 16,683 bp long and is very similar to that of Lyrurus tetrix (16,677 bp). The T. urogallus mitogenome contains the normal 13 protein-coding genes (PCGs), 22 transfer RNAs, 2 ribosomal RNAs, and the control region. The number, order, and orientation of the mitochondrial genes are the same as in L. tetrix and in other species of the same and other bird families. The three domains of the control region contained conserved sequences (ETAS; CSBs), boxes (F, E, D, C, B, BS box), the putative origin of replication of the H-strand (OH) and bidirectional promoters of translation (LSP/HSP).

HPLC-QTOF method for quantifying 11-ketoetiocholanolone, a cortisol metabolite, in ruminants' feces: Optimization and validation.

Studies of animal ecology can benefit from a quantified understanding of eco-physiological processes and, in particular, of the physiological responses in free-ranging animals to potential stressors. The determination of fecal cortisol metabolites as a noninvasive method for monitoring stress has proved to be a powerful tool. High-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) has emerged as the most accurate method for avoiding problems related to the nonspecificity of immunoassays. In this study, we optimize and validate a reliable method using HPLC-MS/MS for quantifying 11-ketoetiocholanolone (11-k), a representative fecal cortisol metabolite in ruminants. An appropriate extraction and purification procedure was developed taking into account the complex nature of feces. The final extract obtained was then analyzed with HPLC-MS/MS using a quadrupole-time-of-fly (QTOF) tandem mass spectrometer with an electrospray ionization interface operating in positive mode, which allowed an unequivocal determination of the metabolite due to its accurate mass capabilities. After rigorous optimization of both sample extraction and the HPLC-QTOF parameters, making use of feces from free-ranging Iberian ibex, ideal conditions were established. Matrix-matched standards were used to calibrate the method. The limit of detection and quantification was 13- and 40- ng/g, respectively. The validation of the method was performed with recoveries in the range of 85-110%, a figure much higher than the 60% obtained with the previous extraction methods used in our laboratory, and with relative standard deviations (RSDs) no higher than 15% for the complete analytical procedure, including extraction and analysis. The time required for the fecal 11-k analysis was greatly reduced in comparison with the previous work carried out in our laboratory. This is the first time that QTOF mass detection coupled with HPLC has been validated for 11-k quantification in feces from free-ranging ruminants such as Iberian ibex. Given the high selectivity and sensitivity attained, our method could become a useful tool for noninvasive stress quantification in ruminants.

Experimental infection of grey partridges with Bagaza virus: pathogenicity evaluation and potential role as a competent host.

Bagaza virus (BAGV; synonymous to Israel turkey meningoencephalomyelitis virus, ITV) is a relevant arthropod-borne epornitic flavivirus. In its first emergence in Europe (southern Spain, 2010) BAGV caused an outbreak, severely affecting red-legged partridges and common pheasants. The effects (pathogenicity, role as reservoir host) of BAGV in other European phasianids are unknown. To fill this gap, grey partridges were experimentally infected with BAGV. The clinical course of the disease was severe, with neurological signs, significant weight loss and 40% mortality. Low viral loads in the blood and the absence of contact transmission suggest a limited-if any-role on BAGV transmission for this European phasianid.

Does wintering north or south of the Sahara correlate with timing and breeding performance in black-tailed godwits?

Migrating long distances requires time and energy, and may interact with an individual's performance during breeding. These seasonal interactions in migratory animals are best described in populations with disjunct nonbreeding distributions. The black-tailed godwit (Limosa limosa limosa), which breeds in agricultural grasslands in Western Europe, has such a disjunct nonbreeding distribution: The majority spend the nonbreeding season in West Africa, while a growing number winters north of the Sahara on the Iberian Peninsula. To test whether crossing the Sahara has an effect on breeding season phenology and reproductive parameters, we examined differences in the timing of arrival, breeding habitat quality, lay date, egg volume, and daily nest survival among godwits (154 females and 157 males), individually marked in a breeding area in the Netherlands for which wintering destination was known on the basis of resightings. We also examined whether individual repeatability in arrival date differed between birds wintering north or south of the Sahara. Contrary to expectation, godwits wintering south of the Sahara arrived two days earlier and initiated their clutch six days earlier than godwits wintering north of the Sahara. Arrival date was equally repeatable for both groups, and egg volume larger in birds wintering north of the Sahara. Despite these differences, we found no association between wintering location and the quality of breeding habitat or nest survival. This suggests that the crossing of an important ecological barrier and doubling of the migration distance, twice a year, do not have clear negative reproductive consequences for some long-distance migrants.

Oestrosis in Asiatic ibex (Capra sibirica): a case report and molecular characterization of larvae.

Three third-instar Oestrus larvae were found in the frontal sinus of an adult female Asiatic ibex (Capra sibirica) in the Tian Shan mountain range, Kyrgyzstan. The larvae were identified as Oestrus ovis based on morphology and after sequencing and analyzing a fragment of the cytochrome oxidase I (COI) gene. In light of this identification and the fact that Asiatic ibex and livestock are sympatric in many areas in Central Asia, we discuss the risks of interspecific parasite spillover.

Molecular characterization of bot flies, Oestrus spp., (Diptera, Oestridae), from domestic and wild Bovidae hosts.

The identification of Oestrus spp. larvae from Bovidae hosts is a difficult task due to the great morphological similarity between species. The lack of unambiguous identification criteria could have also serious epidemiological implications since domestic and wild hosts are sympatric in many natural areas. In order to accurately identify the Oestrus parasitizing hosts, we characterized two different genetic markers, 28S (rRNA) and COI, in larvae collected from domestic sheep and goats, European mouflon and Iberian ibex. Our sequence analyses demonstrate that all samples, except those from Iberian ibex, greatly resembles O. ovis and so we conclude that the species parasitizing this ibex is not O. ovis. Further studies will be needed to confirm whether it is in fact O. caucasicus, as previously suggested, or even a new species.

Distinguishing disease effects from environmental effects in a mountain ungulate: seasonal variation in body weight, hematology, and serum chemistry among Iberian ibex (Capra pyrenaica) affected by sarcoptic mange.

Our study focuses on the Iberian ibex (Capra pyrenaica) from the Sierra Nevada Natural Space (southern Spain), where sarcoptic mange is an endemic disease and animals are affected by a highly seasonal environment. Our aim was to distinguish between disease and environmental influences on seasonal variation in body weight, hematology, and serum biochemistry in Iberian ibex. We sampled 136 chemically immobilized male ibexes. The single effect of mange influenced hemoglobin, hematocrit, mean corpuscular volume, leukocytes, band neutrophils, monocytes, cholesterol, urea, creatine, and aspartate aminotransferase. Both mange and the period of the year also affected values of mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, neutrophils, glucose, and serum proteins. Scabietic animals showed a marked reduction in body weight (21.4 kg on average), which was more pronounced in winter. These results reveal that 1) infested animals are anemic, 2) secondary infections likely occur, and 3) sarcoptic mange is catabolic.

Postural laterality in Iberian ibex Capra pyrenaica: effects of age, sex and nursing suggest stress and social information.

Most studies of lateralized behaviour have to date focused on active behaviour such as sensorial perception and locomotion and little is known about lateralized postures, such as lying, that can potentially magnify the effectiveness of lateralized perception and reaction. Moreover, the relative importance of factors such as sex, age and the stress associated with social status in laterality is now a subject of increasing interest. In this study, we assess the importance of sex, age and reproductive investment in females in lying laterality in the Iberian ibex (Capra pyrenaica). Using generalized additive models under an information-theoretic approach based on the Akaike information criterion, we analyzed lying laterality of 78 individually marked ibexes. Sex, age and nursing appeared as key factors associated, in interaction and non-linearly, with lying laterality. Beyond the benefits of studying laterality with non-linear models, our results highlight the fact that a combination of static factors such as sex, and dynamic factors such as age and stress associated with parental care, are associated with postural laterality.

Advances in studies of disease-navigating webs: Sarcoptes scabiei as a case study.

The discipline of epidemiology is the study of the patterns, causes and effects of health and disease conditions in defined anima populations. It is the key to evidence-based medicine, which is one of the cornerstones of public health. One of the important facets of epidemiology is disease-navigating webs (disease-NW) through which zoonotic and multi-host parasites in general move from one host to another. Epidemiology in this context includes (i) classical epidemiological approaches based on the statistical analysis of disease prevalence and distribution and, more recently, (ii) genetic approaches with approximations of disease-agent population genetics. Both approaches, classical epidemiology and population genetics, are useful for studying disease-NW. However, both have strengths and weaknesses when applied separately, which, unfortunately, is too often current practice. In this paper, we use Sarcoptes scabiei mite epidemiology as a case study to show how important an integrated approach can be in understanding disease-NW and subsequent disease control.

Reliability of an ELISA test for diagnosing oestrosis in Iberian ibex.

Oestrosis is one of the most prevalent parasitosis affecting the Iberian ibex, Capra pyrenaica . To date, both the diagnosis of oestrosis and the determination of the intensity of parasitism require the use of invasive methods (necropsy), which necessarily limit research possibilities. We analyzed the immune humoral response (IgM and IgG) against Oestrus ovis L. excretory/secretory larval antigens in 32 sera taken from Iberian ibex from the Sierra Nevada Natural Space (southern Spain). Three antigens were collected: L1OES (from L1 larvae), L2OES (L2), and L3OES (L3). Necropsy was considered as the gold standard. The percentage of ibexes harboring Oestrus spp. larvae was 88%, the mean intensity of parasitism being 16.96 ± 14.96 larvae per parasitized host (range: 2-52). In our sample, first-instar larvae (L1) were found in 9% of ibexes, while 69% of hosts carried L2 larvae and 88% L3 larvae. Positive correlations between L1 and L2 numbers, and between L2 and L3 numbers were detected. The best results with the immunoenzymatic assay were obtained using IgG antibodies against the L1OES antigens (specificity = 89%; sensitivity = 100%; positive predictive value = 100%; negative predictive value = 57%). The IgG seroprevalence against L1OES was 78%. Thus, the analysis of IgG antibodies against antigens collected from L1 O. ovis larvae would seem to be a noninvasive method for reliably diagnosing oestrosis in naturally infested Iberian ibex. Nevertheless, additional immunological and methodological advances are still required because false positive and false negative results still represent a non-negligible part of the results of the ELISA tests.

Applicability of major histocompatibility complex DRB1 alleles as markers to detect vertebrate hybridization: a case study from Iberian ibex × domestic goat in southern Spain.

BACKGROUND: Hybridization between closely related wild and domestic species is of great concern because it can alter the evolutionary integrity of the affected populations. The high allelic variability of Major Histocompatibility Complex (MHC) loci usually excludes them from being used in studies to detect hybridization events. However, if a) the parental species don't share alleles, and b) one of the parental species possesses an exceptionally low number of alleles (to facilitate analysis), then even MHC loci have the potential to detect hybrids. RESULTS: By genotyping the exon2 of the MHC class II DRB1 locus, we were able to detect hybridization between domestic goats (Capra hircus) and free-ranging Iberian ibex (Capra pyrenaica hispanica) by molecular means. CONCLUSIONS: This is the first documentation of a Capra pyrenaica × Capra hircus hybridization, which presented us the opportunity to test the applicability of MHC loci as new, simple, cost-effective, and time-saving approach to detect hybridization between wild species and their domesticated relatives, thus adding value to MHC genes role in animal conservation and management.

Usefulness of estimated surface area of damaged skin as a proxy of mite load in the monitoring of sarcoptic mange in free-ranging populations of Iberian wild goat, Capra pyrenaica.

In this study we examined the influence of several factors, like the surface of skin with lesions attributable to Sarcoptes scabiei, the time of year and host sex and age on variations of mite load in Iberian wild goats, Capra pyrenaica, from the Sierra Nevada Natural Space, southern Spain. As well, the surface area of skin with scabietic lesions estimated during field surveys were compared with measurements taken in the laboratory and the potential for using categories based on surface areas estimated during monitoring and management programs was analyzed. The surface area of the skin lesions measured in the laboratory and the time of year were the main factors affecting mite load. Results also revealed discrepancies between the surface area of lesions estimated in the field and those measured in the laboratory. The highest error percentages were associated with lesions ranging between 25 and 75% of host skin surface area. By reducing the number of categories of mange infestation (from 5 to 3) the proportion of cases correctly classified using data from field surveys increases. Our analyses suggest that the estimated surface areas of scabietic lesions is a useful relative index of mite abundance and/or intensity of parasitation in Iberian wild goat. Therefore, we conclude that revised classifications should be used in the monitoring of sarcoptic mange in wild populations, since data can be obtained in an inexpensive, fast and non-invasive fashion.

Negative effect of the arthropod parasite, Sarcoptes scabiei, on testes mass in Iberian ibex, Capra pyrenaica.

Testes mass is a key factor in male reproductive success and is potentially exposed to so-called 'parasitic castration'. This is the result of the direct destruction or alteration of reproductive cell lineages (parasitic castration sensu stricto), or the indirect detrimental effects - for example, via body condition - on the ability of progenitors to produce or rear offspring (parasitic castration sensu lato). There are enormous gaps in our knowledge on the effects of parasites on the testes of wild mammals and in an attempt to rectify this dearth of data we examined the relationship between the skin parasite Sarcoptes scabiei and testes mass in Iberian ibex Capra pyrenaica. We considered data from 222 males that were culled in the population from the Sierra Nevada in Spain. Our results provide evidence that sarcoptic mange is associated with reduced size-corrected testes mass in Iberian ibex which supports the hypothesis that parasitism is a determining factor in gonad plasticity in male mammals. We discuss several hypothetical causes of this relationship and highlight the need to deepen the sub-lethal effects of pathogens if we are to accurately understand their modulator effects on host population dynamics.

Sarcoptes scabiei: Specific immune response to sarcoptic mange in the Iberian ibex Capra pyrenaica depends on previous exposure and sex.

Host acquired immunity is a critical factor that conditions the survival of parasites. Nevertheless, there is a shortage of data concerning inter-individual immunological inequalities in wild mammals. Sarcoptic mange is a widespread parasitosis that severely affects mammals such as the Iberian ibex (Capra pyrenaica). Despite some work on the subject, the immune response to sarcoptic mange infestation is still a complex and poorly understood phenomenon. To improve knowledge of the host-Sarcoptes immunological interaction, 18 Iberian ibexes were experimentally infested. IgG levels were assessed using ELISA to test for potential factors determining the specific immune response to infestation. Previous exposure and sex appeared to affect the IgG response to infestation and our results suggest a sex-biased immunomodulation. We discuss the immunological pattern of host-Sarcoptes interactions and also suggest further lines of work that may improve the understanding of immunological interactions of host-Sarcoptes systems.