Food Niche Overlap of Avian Predators (Falconiformes, Strigiformes) in a Field and Forest Mosaic in Central Poland

Food niche overlap statistics are a common way to show competition for food resources in a group of animals. Niche breadths of various species are very variable and their diet composition changes reflecting prey availability. The aim of this study was to evidence the food niche overlap of the whole assemblage of avian predators (eight raptor and owl species, some of them reaching very high densities) in a field and forest mosaic of central Poland. The diet composition was assessed on the basis of pellet analyses and the identification of prey remains found under the nests in the breeding period. The extent of the niche overlap was calculated using a Pianka formula. The food niche overlap indices ranged from 0.02 to 0.93 (mostly below 0.5). The most separate food niche was that of the white-tailed eagle, who regularly preyed on fish. The highest niche overlap was recorded for the common buzzard and common kestrel, two species preying on field rodents, switching to soricomorphs when the former were scarce. Our results confirmed that the food niches of species coexisting in the same area were considerably separate, which is a result of preying on various prey species or searching for them in different habitats.

Feeding of young-of-the-year fishes of the Curonian lagoon of the Baltic sea in 2016

Results of studies on nutrition of juvenile fishes of the Curonian Lagoon of the Baltic Sea are presented. Material on young-of-the-years nutrition was collected in October 2016 during the expeditions of «AtlantNIRO» at 14 standard stations in the Curonian Lagoon. A total of 418 specimens of young-of-the-years were collected and processed. Juveniles of fishes of the Curonian Lagoon were represented by 10 species: pikeperch, bream, roach, perch, smelt, ruffe, three-spined stickleback, ninespine stickleback, bleak and sabrefish. Planktonic and benthic invertebrates formed a basis of the young-of-the-years diet. In most species of juvenile fishes, the nutritional spectra did not differ from the nutritional spectra in the range. An exception was juveniles of the ruff and ninespine stickleback, in which planktonic crustaceans predominated in the diet, while in other reservoirs they consumed bottom organisms. Only Cladocera and Copepoda were found in the diet of roach of juveniles; bottom organisms were absent. In the range of roach juveniles, bottom organisms and mollusks prevailed. The food similarity indices for juvenile fish in the Curonian Lagoon are quite high, which may indicate a tension in food relations between juveniles and (or) partial or complete overlap of their food niches. The weakening of food competition is ensured by the divergence of daily dietary peaks. Three-spined and nine-spined sticklebacks as well as a sabrefish and sticklebacks have the closest food spectrum. On the contrary, sabrefish and bream have a different food spectrum. The peculiarity of feeding of pikeperch juveniles in 2016 was the lack of transition to predatory nutrition.

Change Agents’ Perspectives on Spatial–Relational Proximities and Urban Food Niches

Cities are breeding spaces for innovations in the agro-food sector with the potential to foster the development of local niche networks and a food sustainability transition. In this paper, we propose a conceptual framework for the context-related development of urban food niche organizations and their networks of change agents. With a qualitative analysis of three niche-establishing organizations and their networks, we address the lack of knowledge on spatial–relational dynamics shaping the development of niche organizations and their networks. The identified dynamics are structured along the connotations of geographic, cognitive, social and institutional proximity within the niche networks, to the to the dominant actors, rules, and practices of the urban food system’s regime and to society. For each niche network, we defined a strategic orientation that might lead to a specific development path. Finally, we propose strategies on how cities may foster the development of niche organizations and their networks to highlight local opportunities of supporting a food system sustainability transition, i.e., increasing food literacy, enabling access to space, and engaging in networking.

Floral Resources Partitioning by Two Co-occurring Eusocial Bees in an Afromontane Landscape

Floral preferences of generalist foragers such as eusocial bees influence the success of pollination of many flowering plants, as well as competition with many other bee species in tropical communities. Eusocial bees are important for the pollination success of many flowering plants, as well as for food resources availability for many other species. However, their foraging preferences are still unknown in many tropical areas, especially in the Afrotropics. We studied the foraging activity of two syntopic eusocial bees with large colonies, the honeybee Apis mellifera Linnaeus and the stingless bee Meliplebeia ogouensis (Vachal), on seven plant species in the Bamenda Highlands, Cameroon, in two consecutive years. Simultaneously, we quantified intra- and inter-annual changes in the food resources. We observed resource partitioning among the two bee species. Although both species are considered as generalists, their short-term food niches overlap was very low. Their preferences to the most often visited plants differed even more strongly interannually. Our results bring the first evidence on such relatively strong resource partitioning among two dominant eusocial bee species from West/Central Africa.

FOOD LENOK BRACHYMYSTAX LENOK AND THE BAIKAL GRAYLING THYMALLUS BAICALENSIS MIDDLE REACHES OF THE RIVER CHIKOY (ZABAYKALSKY KRAI)

In 2017, we studied the composition of the bolus Lenka and chorusbridge reaches of the river Chikoy In the stomach, Lenka, grayling and discovered the pupa and imago of amphibiotic insects. The basis of the diet by mass of semimalignant and rucinski. Change of food components in different seasons of observations is established. The composition of the food lenok and grayling is the difference in the different watercourses. All this contributes to the divergence of fish in food niches and more complete use of food resources.

Ecological shifts during larval development in two West African savanna frogs

During their ontogeny many organisms exhibit size and/or stage-specific variability in a variety of features related to morphology and ecology, leading to a shift in the ecological niche between size- or stage groups. We analysed such ecological shifts between four larval stage groups in each of two syntopic species of frogs (a total of 5870 individuals) in two West African savanna ponds in Côte d'Ivoire. We hypothesized and confirmed differences between stage groups in ecological variables related to microhabitat and feeding niche. Stage groups differed up to 1‰ in δ15N and 1.5‰ in δ13C isotopic signatures, up to 10 cm in selected water depth, up to 6 m in distance to the pond's edge, and in the coverage of submerged vegetation (range = 10–50%). However, the hypothesis that tadpoles with generalized mouthparts (Kassina spp.) exhibit more pronounced ontogenetic shifts in food-web position than a specialized filter-feeding species (Phrynomantis microps), and that differences between larval stages are more pronounced in a heterogeneous habitat (offering more choices of habitat and food niches) than in a homogeneous habitat (offering less choices) was only partly confirmed. This study underlines that potential niche shift during different ontogenetic stages is an important factor to be considered in ecological studies.

The Importance of Field-Margin Location for Maintenance of Food Niches for Pollinators

Understanding the factors that have an impact on the diversity of forage flora in the agricultural landscape is a key issue in the maintenance and control of food niches for pollinators. Field margins are common linear structures in the agricultural landscape. In the present study, we evaluated the factors that exert an impact on the forage flora composition and on the diversity in field margins. The study was conducted in the 2010 - 2011 time period across the agricultural landscape on the Lublin Upland of SE Poland. Data on the forage flora were obtained while making floristic charts along 45 transect plots x 300 m; the total length being 13500 m. Multivariate ordination techniques (PCA and RDA) were employed to analyse forage-flora characteristics. Field margins represent valuable refuge areas for forage-species richness, but not for the abundance of forage species. On field margins, forage-species diversity benefits from the location of natural habitats (forests or meadows), primarily if the distance from these habitats is <1000 m or the field acreage is <10 ha. The shift from heterogeneous habitats to a more homogeneous landscape causes a reduction of forage floral diversity. Due to lack of dense forage-species patches, the promotion of sowing nectariferous and/or polleniferous species seems to be a reasonable management method to enhance the quantitative food niche on field margins and to support the conservation of pollinators in the areas surrounding farms.

Autumn-winter diet overlap of fallow, red, and roe deer in forest ecosystems, Southern Poland

The wild population of fallow deer in Central Europe has grown considerably over the last decade. However, information on feeding habits of this alien species in relation to the indigenous red deer or roe deer, in areas of their co-occurrence, is scarce. A prevailing view maintains that their food-niches are distinct, although direct comparative studies have not been carried out. Therefore, the aim of the research was to compare the diets of fallow, red, and roe deer feeding in the same habitat. Research was based on the rumen contents of 242 animals hunted in the autumn-winter season in the forests of Southern Poland. The analyses demonstrated that fallow deer are moderate grazers in such conditions and eat more graminoids in comparison to red or roe deer (36.4% vs. 16.1% or 5.5%, respectively). On the other hand, it feeds on less browse (17.2% vs. 41.4%) or dwarf shrubs (8.4% vs. 19.0%) than red deer, and on less bramble (10.9% vs. 34.6%) or forbs (4.0% vs. 7.6%) in comparison to roe deer (P=0.05). Although the diets of the three deer species differ in terms of the proportion of each food type in their diet, overlapping of their food-niches is high (52.6%).