Nuria Selva

KILL RATES AND PREDATION BY WOLVES ON UNGULATE POPULATIONS IN BIAŁOWIEŻA PRIMEVAL FOREST (POLAND)

Wolf (Canis lupus) kill rates, factors affecting their variation, and predation impact on ungulates were studied in the Polish part of Biaowieza Primeval Forest (580 km 2 ). With the mean size of hunting groups being 4.4 individuals, wolves killed, on average, 0.513 6 0.04 prey·(pack) 21 ·d 21 (mean 6 1 SE); 63% of prey were red deer (Cervus elaphus), 28% were wild boar (Sus scrofa), and 4% were roe deer (Capreolus capreolus). Per capita kill rate averaged 0.116 ungulates·(wolf) 21 ·d 21 , and daily food intake was 5.58 6 0.32 kg·(wolf) 21 ·d 21 . Kill rate on red deer was affected by snow cover (P , 0.001). A pack of wolves killed, on average, 0.264 deer/d in seasons with no snow and 0.587 deer/d when snow was 17 cm deep. The increase in kill rates coincided with a decline in the condition of juvenile (but not adult) deer in late winter (mean marrow fat content in the femur 66% in October-January vs. 27% in February-March). Per capita kill rates decreased slightly (not significantly) with the increasing size of wolf hunting group. However, the amount of food acquired per wolf did not differ among groups containing 2-6 individuals, because larger packs killed bigger prey more often and small prey less frequently than did small packs. Wolf kill rates on wild boar were higher in spring-summer (0.242 6 0.06 boar·(pack) 21 ·d 21 ), when piglets were present, than in autumn-winter (0.106 6 0.04 boar·(pack) 21 ·d 21 ). Annually, wolves killed on average 72 red deer, 16 roe deer, and 31 wild boar over a 100-km 2 area. Compared to prey densities, wolves were an important agent of mortality for red deer only, taking annually 12% of spring-summer (seasonally highest) numbers of deer, which was equivalent to 40% of deer annual increase due to breeding and 40% of their annual mortality. Compared to winter densities (3-6 deer/km 2 ), percentage predation by wolves was inversely density dependent; thus wolves limited deer numbers but did not regulate prey population. By eliminating a substantial proportion of the annual production of the deer population, wolves hamper its growth and prolong the time until it reaches carrying capacity of the habitat. However, wolf predation alone is a poor predictor of deer population dynamics, because deer are also subject to lynx (Lynx lynx) predation and hunting harvest.

Conservation Focus on Europe: Major Conservation Policy Issues That Need to Be Informed by Conservation Science

Europe is one of the worlds most densely populated continents and has a long history of human-dominated land- and seascapes. Europe is also at the forefront of developing and implementing multinational conservation efforts. In this contribution, we describe some top policy issues in Europe that need to be informed by high-quality conservation science. These include evaluation of the effectiveness of the Natura 2000 network of protected sites, implications of rapid economic and subsequent land-use change in Central and Eastern Europe, conservation of marine biodiversity and sustainability of fisheries, the effect of climate change on movement of species in highly fragmented landscapes, and attempts to assess the economic value of ecosystem services and biodiversity. Broad policy issues such as those identified are not easily amenable to scientific experiment. A key challenge at the science-policy interface is to identify the research questions underlying these problem areas so that conservation science can provide evidence to underpin future policy development.

The nested structure of a scavenger community

Scavenging is a widespread phenomenon in vertebrate communities which has rarely been accounted for, in spite of playing an essential role in food webs by enhancing nutrient recycling and community stability. Most studies on scavenger assemblages have often presented an oversimplified view of carrion foraging. Here, we applied for the first time the concept of nestedness to the study of a species-rich scavenger community in a forest ecosystem (Białowieża Primeval Forest, Poland) following a network approach. By analysing one of the most complete datasets existing up to now in a pristine environment, we have shown that the community of facultative scavengers is not randomly assembled but highly nested. A nested pattern means that species-poor carcasses support a subset of the scavenger assemblage occurring at progressively species-rich carcasses. This result contradicts the conventional view of facultative scavenging as random and opportunistic and supports recent findings in scavenging ecology. It also suggests that factors other than competition play a major role in determining community structure. Nested patterns in scavenger communities appear to be promoted by the high diversity in carrion resources and consumers, the differential predictability of the ungulate carcass types and stressful environmental conditions.

A global map of roadless areas and their conservation status

Too many roads Roads have done much to help humanity spread across the planet and maintain global movement and trade. However, roads also damage wild areas and rapidly contribute to habitat degradation and species loss. Ibisch et al. cataloged the worlds roads. Though most of the world is not covered by roads, it is fragmented by them, with only 7% of land patches created by roads being greater than 100 km2. Furthermore, environmental protection of roadless areas is insufficient, which could lead to further degradation of the worlds remaining wildernesses. Science, this issue p. 1423 Roads have fragmented the vast majority of Earth’s terrestrial environment. Roads fragment landscapes and trigger human colonization and degradation of ecosystems, to the detriment of biodiversity and ecosystem functions. The planet’s remaining large and ecologically important tracts of roadless areas sustain key refugia for biodiversity and provide globally relevant ecosystem services. Applying a 1-kilometer buffer to all roads, we present a global map of roadless areas and an assessment of their status, quality, and extent of coverage by protected areas. About 80% of Earth’s terrestrial surface remains roadless, but this area is fragmented into ~600,000 patches, more than half of which are <1 square kilometer and only 7% of which are larger than 100 square kilometers. Global protection of ecologically valuable roadless areas is inadequate. International recognition and protection of roadless areas is urgently needed to halt their continued loss.

Roadless and low-traffic areas as conservation targets in Europe.

With increasing road encroachment, habitat fragmentation by transport infrastructures has been a serious threat for European biodiversity. Areas with no roads or little traffic (“roadless and low-traffic areas”) represent relatively undisturbed natural habitats and functioning ecosystems. They provide many benefits for biodiversity and human societies (e.g., landscape connectivity, barrier against pests and invasions, ecosystem services). Roadless and low-traffic areas, with a lower level of anthropogenic disturbances, are of special relevance in Europe because of their rarity and, in the context of climate change, because of their contribution to higher resilience and buffering capacity within landscape ecosystems. An analysis of European legal instruments illustrates that, although most laws aimed at protecting targets which are inherent to fragmentation, like connectivity, ecosystem processes or integrity, roadless areas are widely neglected as a legal target. A case study in Germany underlines this finding. Although the Natura 2000 network covers a significant proportion of the country (16%), Natura 2000 sites are highly fragmented and most low-traffic areas (75%) lie unprotected outside this network. This proportion is even higher for the old Federal States (western Germany), where only 20% of the low-traffic areas are protected. We propose that the few remaining roadless and low-traffic areas in Europe should be an important focus of conservation efforts; they should be urgently inventoried, included more explicitly in the law and accounted for in transport and urban planning. Considering them as complementary conservation targets would represent a concrete step towards the strengthening and adaptation of the Natura 2000 network to climate change.

Scavenging on European bison carcasses in Bialowieza Primeval Forest (eastern Poland)

Abstract We investigated the utilization of European bison, Bison bonasus, carcasses by the scavenging guild in Bialowieza Primeval Forest (eastern Poland) during 1997-2001. Twelve carcasses were monitored in systematic visits till total depletion (N=303). Thirteen species of birds and mammals utilized bison carcasses. Most frequent scavengers and their mean scavenging frequencies (mean percentage of visits to each carcass with a given scavenger species recorded) were raven, Corvus corax, 72% red fox, Vulpes vulpes, 41% wolf, Canis lupus, 29% common buzzard, Buteo buteo, 23% raccoon dog, Nyctereutes procyonoides, 20% and white-tailed eagle, Haliaeetus albicilla, 16%. Ravens and white-tailed eagles were observed significantly more often at carcasses placed in clearings than at those exposed in the forest. The opposite was recorded for raccoon dogs. Manifest habitat segregation was also found for flocks of immature ravens and territorial pairs. Wolves had an important facilitation effect for other species and triggered their scavenging activity. Bison carcasses were utilized for an average of 106 ± 61 days (mean ± SD), to over 80% of live weight consumed. The estimated mean daily consumption by all scavengers was 3 kg day-1 (range 0-68), being highest during the first 2 weeks (6.8 ± 6.2 kg day-1). The utilization time of bison carcasses depended on the index of carcass openness, the number of wolf feeding visits to the carcass, the date of carcass exposure, and the habitat type (forest versus open clearings). Ambient temperature had a significant effect on the rate of carcass depletion, while the effects of snow cover and precipitation were negligible.

The challenge of implementing the European network of protected areas Natura 2000.

Established under the European Union (EU) Birds and Habitats Directives, Natura 2000 is one of the largest international networks of protected areas. With the spatial designation of sites by the EU member states almost finalized, the biggest challenge still lying ahead is the appropriate management of the sites. To evaluate the cross-scale functioning of Natura 2000 implementation, we analyzed 242 questionnaires completed by conservation scientists involved in the implementation of Natura 2000 in 24 EU member states. Respondents identified 7 key drivers of the quality of Natura 2000 implementation. Ordered in decreasing evaluation score, these drivers included: network design, use of external resources, legal frame, scientific input, procedural frame, social input, and national or local policy. Overall, conservation scientists were moderately satisfied with the implementation of Natura 2000. Tree modeling revealed that poor application of results of environmental impact assessments (EIA) was considered a major constraint. The main strengths of the network included the substantial increase of scientific knowledge of the sites, the contribution of nongovernmental organizations, the adequate network design in terms of area and representativeness, and the adequacy of the EU legal frame. The main weaknesses of Natura 2000 were the lack of political will from local and national governments toward effective implementation; the negative attitude of local stakeholders; the lack of background knowledge of local stakeholders, which prevented well-informed policy decisions; and the understaffing of Natura 2000 management authorities. Top suggestions to improve Natura 2000 implementation were increase public awareness, provide environmental education to local communities, involve high-quality conservation experts, strengthen quality control of EIA studies, and establish a specific Natura 2000 fund.

Inter‐specific interactions linking predation and scavenging in terrestrial vertebrate assemblages

Predation and scavenging have been classically understood as independent processes, with predator–prey interactions and scavenger–carrion relationships occurring separately. However, the mere recognition that most predators also scavenge at variable rates, which has been traditionally ignored in food‐web and community ecology, leads to a number of emergent interaction routes linking predation and scavenging. The general goal of this review is to draw attention to the main inter‐specific interactions connecting predators (particularly, large mammalian carnivores), their live prey (mainly ungulates), vultures and carrion production in terrestrial assemblages of vertebrates. Overall, we report an intricate network of both direct (competition, facilitation) and indirect (hyperpredation, hypopredation) processes, and provide a conceptual framework for the future development of this promising topic in ecological, evolutionary and biodiversity conservation research. The classic view that scavenging does not affect the population dynamics of consumed organisms is questioned, as multiple indirect top‐down effects emerge when considering carrion and its facultative consumption by predators as fundamental and dynamic components of food webs. Stimulating although challenging research opportunities arise from the study of the interactions among living and detrital or non‐living resource pools in food webs.

Unforeseen Effects of Supplementary Feeding: Ungulate Baiting Sites as Hotspots for Ground-Nest Predation

Despite the ubiquity and magnitude of food provision to wildlife, our understanding of its ecological effects and conservation implications is very limited. Supplementary feeding of ungulates, still one of the main paradigms of game management in Europe, occurs in natural areas on an enormous scale. We investigated the indirect effects of this practice on nest predation risk in the Polish Eastern Carpathians (Bieszczady Mountains). We hypothesized that the predators attracted to ungulate baiting sites would also forage for alternative prey nearby, increasing the nest predation risk for ground-nesting birds in the vicinity. We conducted a paired experiment by placing artificial nests (N = 120) in feeding and control sites (N = 12) at different distances from the ungulate feeding site. We also documented the use of three ungulate feeding sites by potential nest predators with automatic cameras. The proportion of depredated nests was 30% higher in the vicinity of feeding sites than at control sites (65%±31.5 vs 35%±32.1). The probability of a nest being depredated significantly increased with time and at shorter distances from the feeding site. We predicted that the area within 1-km distance from the feeding site would have a high risk (>0.5) of nest predation. We recorded 13 species of potential ground-nest predators at ungulate baiting sites. Most frequent were Eurasian jays Garrulus glandarius, mice and voles Muroidea, ravens Corvus corax, brown bears Ursus arctos, and wild boar Sus scrofa. Nest predators made most use of supplementary feeding sites (82% pictures with predators vs 8% with ungulates, the target group). Our study alerts of the impacts of ungulate feeding on alternative prey; this is of special concern when affecting protected species. We urge for a sensible management of ungulate feeding, which considers potential indirect effects on other species and the spatial and temporal components of food provision.

Logging and forest edges reduce redundancy in plant-frugivore networks in an old-growth European forest

Summary1. Seed dispersal by frugivores is the basis for regeneration of fleshy-fruited plants in forest ecosys-tems. Previous studies have reported a decrease in forest specialist frugivores due to logging andforest edges. Forest generalists appear less sensitive and may even increase at forest edges. Suchchanges in the abundance of frugivores may have consequences for consumer/resource ratios andcompetition in plant–frugivore networks.2. Optimal foraging theory predicts an increase in dietary specialization of animals at low consumer/resource ratios due to reduced competition. A decrease in forest specialists in logged forests shouldcause decreased consumer/resource ratios, increased dietary specialization and reduced redundancy,whereas an increased abundance of forest generalists at edges may compensate for a loss of specialists.3. In Europe’s last old-growth lowland forest (Bialowieza, Eastern Poland), we recorded fruit_removal by frugivores from fleshy-fruited plant species in the interior and at edges of logged andold-growth forests for 2 consecutive years.4. The abundance of forest generalists increased at forest edges, whereas specialists were unaffected.Conversely, logging resulted in a decrease in abundance of forest specialists but had no effect onthe abundance of generalists. Accordingly, consumer/resource ratios increased from interior to edgesand were reduced in the interior of logged forests compared with the interior of old-growth forests.As predicted by optimal foraging theory, a decrease in consumer/resource ratios coincided withincreased dietary specialization and a loss of redundancy in the interior of logged forests. Despitelow dietary specialization, redundancy was reduced at forest edges as forest generalists dominatedplant–frugivore interactions.5. Synthesis. We show that a shift in frugivore assemblages at forest edges and increased dietaryspecialization of frugivores in the interior of logged forests involved a loss of redundancy comparedwith continuous old-growth forests. This suggests that seed dispersal services in secondary foresthabitats depend on an impoverished subset of dispersal vectors and may suffer reduced adaptivepotential to changing environmental conditions. Thus, our study highlights the value of old-growthforests for the conservation of frugivore-mediated seed dispersal processes.Key-words: Bialowieza Forest, ecosystem services, functional niche, mutualistic networks, optimal_foraging, plant–animal interactions, resource specialization, seed dispersalIntroduction