Diet of the little Athene noctua (Scopoli, 1769) on the territory of Berehovo district (Transcarpathian region)

Objectives. The Little Owl is the most common owl in the Western Palearctic and its population is declining significantly in Europe. Therefore, conservation and study of this owl is an important issue in most European countries. Analysis of trophic patterns at the local level provides interesting and valuable information about the predator’s eating habits. The owl’s diet investigation allows us to analyze their potential adaptations to habitats with different levels of environmental transformation. Materials and Methods. We studied nutrition of the Little Owl Athene noctua, in agricultural lands of Berehove district of Transcarpathian region in Ukraine. In total, 1446 pellets were collected at 15 pellet stations in 2002–2020 and 2506 prey items were identified. The prey items represented 18 vertebrate species (16 species of small mammals of three orders Rodentia, Soricomorpha, Carnivora, as well as reptiles of the family Lacertidae and birds of the order Passeriformes and arthropods. Results. Vertebrates play a major role in feeding the Little Owl (over 99 % of total prey biomass in all of the studied sites). The common vole is the most common prey in the owl’s diet (52.1 % of the total prey number and 67.5 % of the biomass of the prey caught), as well as a high proportion of mice of the genus Apodemus and Sylvaemus. The contribution of invertebrates to total prey biomass is insignificant (0.3 %). A large number of invertebrates were observed in the diet of the Owl in summer and were almost completely absent in winter. Conclusions. According to our data, the Little Owl is a typical predator generalist in Transcarpathia. The 28 taxa found in the pellets show a wide range of food objects in a relatively small area, and high level adaptations to habitats with different levels of environmental transformation (agrosystems and anthropogenic areas).

Prey Capture in Anthocyanin-free Sarracenia leucophylla (Sarraceniaceae) Is Associated with Leaf Size, But Not Red Pigmentation

Anthocyanin pigmentation is a significant horticultural feature in plants and can be a crucial mediator of plant–insect interactions. In carnivorous plants, the modified leaves that capture prey can be visually striking and are traditionally considered prey attractants. Nevertheless, the question of whether bold color and venation patterns function as lures for insect prey remains ambiguous, and appears to vary across taxa. Furthermore, vegetative pigments can have alternate functions as protectants against thermal and oxidative damage. Our dual-year study compares the wild-type pitcher phenotype with a true-breeding anthocyanin-free mutant of the white-topped pitcher plant (Sarracenia leucophylla Raf.). We bred full-sibling crosses of S. leucophylla carrying either the wild-type anthocyanin gene or the anthocyanin-free variant. In both experimental years, growth points were established in outdoor plots and pitchers were allowed to capture prey before harvest at the end of each growing season. Dry weight of prey biomass was measured from pitchers of both pigment morphs, along with nectary counts, pitcher size, and internal temperature. The presence of anthocyanins in trapping leaves did not affect the biomass of insects captured. Nor did wild-type or anthocyanin-free pitcher morphs differ in size, temperature, or nectary counts. Instead, pitcher height, and, nominally, mouth diameter were better predictors of prey biomass. Despite striking visual differences in pitcher color, wild-type and anthocyanin-free plants did not catch significantly different quantities of prey. Our study provides empirical data that anthocyanin pigmentation in S. leucophylla does not affect the capture of prey biomass, and supports a growing body of literature showing that pigmentation traits serve in multiple contexts.

Diet of Leopards Panthera pardus fusca inhabiting protected areas and human-dominated landscapes in Goa, India

The diet of leopards occupying human-dominated and protected areas (PAs) in Goa, India was analyzed through scat analysis. A total of 117 scats, 55 from wildlife sanctuaries/ national parks and 62 from human-dominated areas were collected and analyzed. Analysis of 55 scats from protected forest revealed the presence of only wild prey in the leopard diet, whereas 61% of scats collected from human-dominated areas consisted of only wild prey, 29% of domesticated animals, and 10% a mixture of both wild prey & domesticated animals. Of the prey biomass consumed in human-dominated areas, domestic animals constituted only 33% of the leopard diet. Among all leopard scats, 71% contained only one prey species, 28% contained two species, and 1% contained three.

Food talk: 40-Hz fin whale calls are associated with prey biomass

Animals use varied acoustic signals that play critical roles in their lives. Understanding the function of these signals may inform about key life-history processes relevant for conservation. In the case of fin whales ( Balaenoptera physalus ), that produce different call types associated with different behaviours, several hypotheses have emerged regarding call function, but the topic still remains in its infancy. Here, we investigate the potential function of two fin whale vocalizations, the song-forming 20-Hz call and the 40-Hz call, by examining their production in relation to season, year and prey biomass. Our results showed that the production of 20-Hz calls was strongly influenced by season, with a clear peak during the breeding months, and secondarily by year, likely due to changes in whale abundance. These results support the reproductive function of the 20-Hz song used as an acoustic display. Conversely, season and year had no effect on variation in 40-Hz calling rates, but prey biomass did. This is the first study linking 40-Hz call activity to prey biomass, supporting the previously suggested food-associated function of this call. Understanding the functions of animal signals can help identifying functional habitats and predict the negative effects of human activities with important implications for conservation.

Inter-individual variation in provisioning rate, prey size and number, and links to total prey biomass delivered to nestlings in the Collared Flycatcher (Ficedula albicollis)

Background In bird species where offspring growth and survival rely on parents’ food provisioning, parents can maximise their fitness by increasing the quantity and/or the quality of preys delivered to their offspring. Many studies have focused on inter-individual variation in feeding rate, yet this measure may not accurately reflect the total amount of food (i.e. energy) provided by parents if there is large variation in the quantity and quality of preys at each feeding. Here, we explored the relative role of individual (sex, age, body condition), breeding (hatching date, brood size) and environmental (temperature) factors on feeding rate, prey number, size and quality, and their contribution to total prey biomass delivered to the nestlings of 164 Collared Flycatcher (Ficedula albicollis) parents in 98 nests. Results Preys delivered to the nest were mainly larvae (53.6%) and flying insects (45.6%). Feeding rate increased with brood size and age, and was higher in males than females. Mean prey number decreased, but mean prey size increased, as the season progressed and parents feeding their brood with primary larvae brought more preys per visit. Relationships between feeding rate, mean prey number and size remained when taking into account the provisioning quality: parents brought either a large number of small prey or a small number of larger items, and the force of the trade-offs between feeding rate and mean prey number and size depended on the quality of the provisioning of the parents. Whatever the percentage of larvae among preys in the provisioning, the variance in total prey biomass was foremost explained by feeding rate (65.1% to 76.6%) compared to mean prey number (16.4% to 26%) and prey size (2.7% to 4%). Conclusions Our study shows that variation in feeding rate, prey number, size, but not quality (i.e. percentage of larvae), were influenced by individual factors (sex and age) and breeding decisions (brood size and timing of breeding) and that, whatever the provisioning strategy adopted, feeding rate was the best proxy of the total biomass delivered to the nestlings.

Predator stomach contents can provide accurate indices of prey biomass

Diet-based annual biomass indices can potentially use predator stomach contents to provide information about prey biomass and may be particularly useful for species that are otherwise poorly sampled, including ecologically important forage fishes. However, diet-based biomass indices may be sensitive to underlying ecological dynamics between predators and prey, such as predator functional responses and changes in overlap in space and time. To evaluate these factors, we fit spatio-temporal models to stomach contents of five Atlantic herring (Clupea harengus) predators and survey catch data for predators and Atlantic herring. We identified drivers of variation in stomach contents, evaluated spatial patterns in stomach content data, and produced predator-specific indices of seasonal Atlantic herring biomass. After controlling for spatio-temporal processes and predator length, diet-based indices of biomass shared similar decadal trends but varied substantially between predators and seasons on shorter time scales. Diet-based indices reflected prey biomass more than prey availability, but weak correlations indicated that not all biological processes were controlled for. Results provide potential guidance for developing diet-based biomass indices and contribute to a body of evidence demonstrating the utility of predator diet data to provide information about relative prey biomass.

Natural dimethyl sulfide gradients would lead marine predators to higher prey biomass

Finding prey is essential to survival, with marine predators hypothesised to track chemicals such as dimethyl sulfide (DMS) while foraging. Many predators are attracted to artificially released DMS, and laboratory experiments have shown that zooplankton grazing on phytoplankton accelerates DMS release. However, whether natural DMS concentrations are useful for predators and correlated to areas of high prey biomass remains a fundamental knowledge gap. Here, we used concurrent hydroacoustic surveys and in situ DMS measurements to present evidence that zooplankton biomass is spatially correlated to natural DMS concentration in air and seawater. Using agent simulations, we also show that following gradients of DMS would lead zooplankton predators to areas of higher prey biomass than swimming randomly. Further understanding of the conditions and scales over which these gradients occur, and how they are used by predators, is essential to predicting the impact of future changes in the ocean on predator foraging success.

Assessing prey selection of snow leopard in Mt. Kangchenjunga, Nepal

In spring of 2012, we studied the feeding habits of snow leopard using a comprehensive approach that combines fecal genetic sampling, macro and microscopic analysis of snow leopard diets and direct observation of Naur and livestock in Kangchenjunga Conservation Area of east Nepal. Out of collected 88 putative snow leopard scat samples from 140 transects (290 km) in 27 (4*4 km2) sampling grid cells, 83% were confirmed to be from snow leopard. The genetic analysis accounted for 19 individual snow leopards (10 male and 9 female) with a mean population size estimate of 24 (95% CI: 19- 29), and an average density of 3.9 snow leopards/100 km2 within 609 km2. Total available prey biomass of Naur and Yak was estimated at 355,236 kg (505 kg yak/km2 and 78 kg Naur/km2). From the available prey biomass, we estimated snow leopards consumed 7% annually which was comprised of wild prey (49%), domestic livestock (45%), and 6% unidentified items. The estimated 47,736 kg Naur biomass gives a snow leopard-Naur ratio of 1: 59 on a weight basis. The proportion of young Naur was estimated at 17%, with an almost double predation rate at 28%. Predators such as common leopard and wolf share the same habitat and might compete with snow leopard for prey which will likely influence future predator-prey associations in KCA. Along with livestock insurance scheme improvement, there needs to be a focus on improved livestock guarding as well as engaging and educating local people to be citizen scientists on the importance of snow leopard conservation, involving them in long-term monitoring programs and promotion of ecotourism.

Assessing prey selection of snow leopard in Mt. Kangchenjunga, Nepal

In spring of 2012, we studied the feeding habits of snow leopard using a comprehensive approach that combines fecal genetic sampling, macro and microscopic analysis of snow leopard diets and direct observation of Naur and livestock in Kangchenjunga Conservation Area of east Nepal. Out of collected 88 putative snow leopard scat samples from 140 transects (290 km) in 27 (4*4 km2) sampling grid cells, 83% were confirmed to be from snow leopard. The genetic analysis accounted for 19 individual snow leopards (10 male and 9 female) with a mean population size estimate of 24 (95% CI: 19- 29), and an average density of 3.9 snow leopards/100 km2 within 609 km2. Total available prey biomass of Naur and Yak was estimated at 355,236 kg (505 kg yak/km2 and 78 kg Naur/km2). From the available prey biomass, we estimated snow leopards consumed 7% annually which was comprised of wild prey (49%), domestic livestock (45%), and 6% unidentified items. The estimated 47,736 kg Naur biomass gives a snow leopard-Naur ratio of 1: 59 on a weight basis. The proportion of young Naur was estimated at 17%, with an almost double predation rate at 28%. Predators such as common leopard and wolf share the same habitat and might compete with snow leopard for prey which will likely influence future predator-prey associations in KCA. Along with livestock insurance scheme improvement, there needs to be a focus on improved livestock guarding as well as engaging and educating local people to be citizen scientists on the importance of snow leopard conservation, involving them in long-term monitoring programs and promotion of ecotourism.