S.E. van Wieren

The effect of personality on social foraging: shy barnacle geese scrounge more

Animals foraging in groups can either search for food themselves (producing) or search for the food discoveries of other individuals (scrounging). Tactic use in producer–scrounger games is partly flexible but individuals tend to show consistency in tactic use under different conditions suggesting that personality might play a role in tactic use in producer–scrounger games. Here we studied the use of producing and scrounging tactics by bold and shy barnacle geese (Branta leucopsis), where boldness is a personality trait known to be repeatable over time in this species. We defined individuals as bold, shy or intermediate based on two novel object tests. We scored the frequency of finding food patches (the outcome of investing in producing) and joining patches (the outcome of investing in scrounging) by bold and shy individuals and their feeding time. Shy individuals had a higher frequency of joining than bold individuals, demonstrating for the first time that personality is associated with tactic use in a producer–scrounger game. Bold individuals tended to spend more time feeding than shy individuals. Our results highlight the importance of including individual behavioural variation in models of producer–scrounger games.

Ungulates in temperate forest ecosystems

1. Ungulates and forest management Forest management is currently undergoing major changes, both in Western Europe and in North Amer- ica (Von SchGppfer, 1983; Thomas, 1994). Forestry becomes more oriented towards ecosystem manage- ment, with natural processes promoted and indige- nous species and multi-species forest stands favoured. Strictly regulated, even-aged forestry practices are becoming less common. Forest clearfelling is prac- tised on a smaller scale, thus preventing major dis- turbance of the forest microclimate. Spontaneous regeneration is stimulated in commercial forests by partly thinning of canopies or by small clearcuts, and structural diversity of managed stands is enhanced. In this ‘nature-following forestry’, silvicultural treat- ments are carried out in such a way that the habitat of typical forest plants, wildlife, insects and microor- ganisms is less affected. Sustainable forestry and biodiversity are items of growing importance in this type of forest management. In addition, after decades of reduction, in most countries forest cover is ex- panding again, related to the set-aside of agricultural land and other land-use changes. These new goals in forest management have far- reaching implications for the area and quality of ungulate habitats, for the ungulate populations and for their management. In the past, large herbivorous mammals were often seen as ‘pest species’, conflict-

Genome-wide single nucleotide polymorphism analysis reveals recent genetic introgression from domestic pigs into Northwest European wild boar populations.

Present‐day genetic introgression from domestic pigs into European wild boar has been suggested in various studies. However, no hybrids have been identified beyond doubt mainly because available methods were unable to quantify the extent of introgression and rule out natural processes. Genetic introgression from domestic pigs may have far‐reaching ecological consequences by altering traits like the reproduction rate or immunology of wild boar. In this study, we demonstrate a novel approach to investigate genetic introgression in a Northwest (NW) European wild boar data set using a genome‐wide single nucleotide polymorphism (SNP) assay developed for domestic pigs. We quantified the extent of introgression using allele frequency spectrum analysis, in silico hybridization simulations and genome distribution patterns of introgressed SNPs. Levels of recent introgression in the study area were expected to be low, as pig farming practices are prevailingly intensive and indoors. However, evidence was found for geographically widespread presence of domestic pig SNPs in 10% of analysed wild boar. This was supported by the identification of two different pig mitochondrial DNA haplotypes in three of the identified hybrid wild boar, suggesting that introgression had occurred from multiple sources (pig breeds). In silico hybridization simulations showed that the level of introgression in the identified hybrid wild boar is equivalent to first‐generation hybrids until fifth‐generation backcrosses with wild boar. The distribution pattern of introgressed SNPs supported these assignments in four of nine hybrids. The other five hybrids are considered advanced‐generation hybrids, resulting from interbreeding among hybrid individuals. Three of nine hybrids were genetically associated with a different wild boar population than the one in which they were sampled. This discrepancy suggests that genetic introgression has occurred through the escape or release of an already hybridized farmed wild boar stock. We conclude that genetic introgression from domestic pigs into NW European wild boar populations is more recent and more common than expected and that genome‐wide SNP analysis is a promising tool to quantify recent hybridization in free‐living populations.

The role of seed size in dispersal by a scatter-hoarding rodent

Patrick A. Jansen,1 Martijn Bartholomeus,2 Frans Bongers,1 Jelmer A. Elzinga,2,* Jan den Ouden1 and Sipke E. Van Wieren2 1Silviculture and Forest Ecology Group, Department of Environmental Sciences, Wageningen University, PO Box 342, NL-6700 AH Wageningen, The Netherlands; 2Tropical Nature Conservation and Vertebrate Ecology Group, Department of Environmental Sciences, Wageningen University, Bornsesteeg 69, NL-6708 PD Wageningen, The Netherlands

Flight distance in roe deer Capreolus capreolus and fallow deer Dama dama as related to hunting and other factors

Flight distances in roe deer Capreolus capreolus and fallow deer Dama dama with respect to a human observer on foot were measured in four nature reserves in the Netherlands: two dune reserves in the western part (the Amsterdam Water Supply Dunes (AWD) and Kennemerduinen (KD)) and two forested areas in the eastern part of the country (Hoge Veluwe (HV) and Kootwijk (KO)). In the four areas there is a gradient in hunting pressure from almost none in the AWD, via an increase in KD, to KO and HV. Fallow deer occur in both of the dune reserves and are not hunted. Of all the factors studied, hunting regime and habitat structure were most strongly related to flight distance. Although the number of individuals per group and most weather conditions also showed some relation to flight distances, their influence was relatively unimportant compared to that of hunting regime and habitat structure. When walking down wind, deer (both roe and fallow deer) flee at longer distances (64.7 ± 5.8 m) than when walking upwind (41.7 ± 3.3 m) or in calm wind (44.2 ±1.8 m). In the roe deer population of the AWD, flight distances were the shortest among all the studied areas. In both of the dune areas, the flight distances in dense vegetation structures were shorter than in open field. Fallow deer flight distances did not differ between the dune reserves AWD and KD.

Do large herbivores select a diet that maximizes short-term energy intake rate?

Using field data on diet composition, diet quality and eating behaviour of three species of herbivores (red deer, Highland cattle and Konik ponies) it was tested if herbivores select their diet according to the intake rate maximizing principle. The digestible organic matter intake rate (DOMIR) was used as test parameter. Across all species and diets, 61% of the diet composition could be explained by rate maximization, ponies having the lowest (52.1%) and red deer having the highest (72.1%) proportion of the highest DOMIR-preference class in their diet. Possible reasons for not selecting a perfect optimal diet in the sense of energy maximization include estimation errors, the lack of inclusion of nutrient constraints in the model, and the effects of living in a complex and constantly changing environment leading to ‘imperfect’ foraging decisions. Despite the imperfections, the results do lend substantial credit to the rate maximizing view.

Prevalence of Coxiella Burnetii in Ticks After a Large Outbreak of Q Fever

Q fever has emerged as an important human and veterinary public health problem in the Netherlands with major outbreaks in three consecutive years. Goat farms are probably the prime source from which Coxiella burnetii have spread throughout the environment, infecting people living in the vicinity. Coxiella burnetii infection not only spilled over from animal husbandry to humans but could also have spread to neighbouring wildlife and pets forming novel reservoirs and consequently posing another and lingering threat to humans, companion animals and livestock. In these cases, transmission routes other than airborne spread of contaminated aerosols may become significant. Therefore, the role of ticks in the transmission of Coxiella burnetii in the current situation was investigated. A total of 1891 questing Ixodes ricinus ticks and 1086 ticks feeding on pets, wildlife and livestock were tested by a recently developed multiplex Q‐PCR. All ticks were negative, except for a few ticks feeding on a herd of recently vaccinated sheep. Coxiella‐positive ticks were not detected after resampling this particular herd three months later. Based on these data we conclude that the current risk of acquiring Q fever from questing ticks in the Netherlands is negligible. However, for future risk assessments, it might be relevant to sample more ticks in the vicinity of previously C. burnetii infected goat farms and to assess whether C. burnetii can be transmitted transovarially and transstadially in I. ricinus ticks.

Diet selection by roe deer Capreolus capreolus in Kielder Forest in relation to plant cover

Abstract The diet of roe deer Capreolus capreolus in relation to the cover and abundance of ground vegetation was investigated at two sites in Kielder Forest, Northumberland. Positive selection was found for heather Calluna vulgaris , other dicotyledons and evergreen ferns, which together formed a large part of the diet. Coarse monocotyledons were avoided. Sitka spruce Picea sitchensis formed a significant part of the diet in spring. Differences in the diet were apparent between the two sites, with more Sitka spruce eaten and more browsing damage occurring on the site with the poorer soil type. The management implications of these results are discussed.

Few vertebrate species dominate the Borrelia burgdorferi s.l. Life cycle

Background. In the northern hemisphere, ticks of the Ixodidae family are vectors of diseases such as Lyme borreliosis, Rocky Mountain spotted fever and tick-borne encephalitis. Most of these ticks are generalists and have a three-host life cycle for which they are dependent on three different hosts for their blood meal. Finding out which host species contribute most in maintaining ticks and the pathogens they transmit, is imperative in understanding the drivers behind the dynamics of a disease. Methods. We performed a systematic review to identify the most important vertebrate host species for Ixodes ricinus and Borrelia burgdorferi s.l. as a well-studied model system for tick-borne diseases. We analyzed data from 66 publications and quantified the relative contribution for 15 host species. Review results. We found a positive correlation between host body mass and tick burdens for the different stages of I. ricinus. We show that nymphal burdens of host species are positively correlated with infection prevalence with B. burgdorferi s.l., which is again positively correlated with the realized reservoir competence of a host species for B. burgdorferi s.l. Our quantification method suggests that only a few host species, which are amongst the most widespread species in the environment (rodents, thrushes and deer), feed the majority of I. ricinus individuals and that rodents infect the majority of I. ricinus larvae with B. burgdorferi s.l. Discussion. We argue that small mammal-transmitted Borrelia spp. are maintained due to the high density of their reservoir hosts, while bird-transmitted Borrelia spp. are maintained due to the high infection prevalence of their reservoir hosts. Our findings suggest that Ixodes ricinus and Borrelia burgdorferi s.l. populations are maintained by a few widespread host species. The increase in distribution and abundance of these species, could be the cause for the increase in Lyme borreliosis incidence in Europe in recent decades.

Nitrogen prediction in grasses: effect of bandwidth and plant material state on absorption feature selection

We analysed stability and predictive capabilities of known nitrogen absorption features between plant material prepared for NIRS (dried) and RS (fresh) studies. Grass spectra were taken of the plant canopy, and again after the grass sample was dried and ground. Models were derived using stepwise multiple linear regression (sMLR). Regression values (adj.r 2) produced using the dried material were greater than those produced using canopy material. For dried material only wavebands from the SWIR region were selected. Wavebands selected by sMLR on canopy material were located in both the VNIR and SWIR regions. Using wavebands selected for dried material models produced low adj.r 2 values when applied to canopy plant material; differences in adj.r 2 values are smaller when wavebands selected in canopy material models are applied to dried material. Widening of nitrogen features produced higher adj.r 2 values for both dried and canopy material. This work shows that obtaining models with high predictive capabilities for nitrogen concentration is possible, but waveband selection should not be limited to features identified by NIRS studies. To accommodate for variability in absorption features, and instrument errors, absorption features should be widened.