Seasonal Diet Research Articles

Вовк (Canis lupus) півночі Центрального Полісся: раціон, екологічна ніша та вибірковість хижацтва

The diet of the wolf in the Chornobyl Radiation and Ecological Biosphere Reserve (ChBR) due to the high proportion of the red deer (Cervus elaphus) in its diet is generally uncharacteristic of the Polissia and occupies an intermediate position between the diets of wolves in Central Europe and the Polissia. The wolf is a highly flexible carnivore with a diet that can change depending on the time and location. In the context of climate change, the drying of marshes, high winter temperatures, and heat stress, the elk as a species of northern origin is vulnerable to wolf predation. This fact explains the high proportion of elk in the ChBR in the wolf’s diet in 2019–2020, when cases of elk deaths from wolves were recorded even in small fire ponds. Preliminary data indicate significant changes in the seasonal diet of wolves in the ChBR and an increase in the proportion of elk in it in the winter, when this species migrates from Belarus. The construction of a fence on the Ukrainian–Belarusian border may lead to a decrease in the number of elk due to reduced migration and a corresponding decrease in the share of this species in the wolf’s diet. The current epizootic of African wild boar fever has led to a long-term depression of the boar population and a small share of this species in the wolf’s diet. There are no grounds for a rapid recovery of the wild boar population and its high representation in the wolf diet in the near future. The fluctuations in the ‘wolf–elk’ and ‘wolf–deer’ systems during the climatic anomaly of 2019–2020 almost completely levelled out in the next two years. In the first year, there was a sharp shift towards minimising elk losses, then the situation levelled off, and the wolf’s dietary spectrum has remained almost unchanged to date. Beaver demonstrates a change in the selectivity of wolf predation. In hot and dry years, it is more intensively preyed on by wolves, and less so in more watered cooler years (with changes in selective predation from +0.25 to -0.25). Deer is the only species that sharply reduces its vulnerability to wolf predation in abnormally warm and dry years (selective predation is less than -0.6). When determining the selectivity of wolf predation, it is advisable to map (record GIS coordinates) the findings of wolf excrements.

The Inca child of the Quehuar volcano: Stable isotopes clue to geographic origin and seasonal diet, with putative seaweed consumption

The Inca child of the Quehuar volcano: Stable isotopes clue to geographic origin and seasonal diet, with putative seaweed consumption

Evidence for resource partitioning in weakfishes from a coastal upwelling ecosystem

Evidence for resource partitioning in weakfishes from a coastal upwelling ecosystem

Diet and feeding ecology of the pike perch (Sander lucioperca), an invasive fish species: seasonal diet shifts

Diet and feeding ecology of the pike perch (Sander lucioperca), an invasive fish species: seasonal diet shifts

Body size modulates the extent of seasonal diet switching by large mammalian herbivores in Yellowstone National Park.

Prevailing theories about animal foraging behaviours and the food webs they occupy offer divergent predictions about whether seasonally limited food availability promotes dietary diversification or specialization. Emphasis on how animals compete for food predominates in work on the foraging ecology of large mammalian herbivores, whereas emphasis on how the diversity of available foods generally constrains dietary opportunity predominates work on entire food webs. Reconciling predictions about what promotes dietary diversification is challenging because species' different body sizes and mobilities modulate how they seek and compete for resources-the mechanistic bases of common predictions may not pertain to all species equally. We evaluated predictions about five large-herbivore species that differ in body size and mobility in Yellowstone National Park using GPS tracking and dietary DNA. The data illuminated remarkably strong and significant correlations between body size and five key indicators of diet seasonality (R 2 = 0.71-0.80). Compared to smaller species, bison and elk showed muted diet seasonality and maintained access to more unique foods when winter conditions constrained food availability. Evidence from GPS collars revealed size-based differences in species' seasonal movements and habitat-use patterns, suggesting that better accounting for the allometry of foraging behaviours may help reconcile disparate ideas about the ecological drivers of seasonal diet switching.

Seasonal changes in invertebrate diet of breeding black-necked cranes (Grus nigricollis).

Invertebrates greatly support the growth, development, and reproduction of insectivorous birds. However, the influence of human activity (e.g., pesticide use, deforestation, and urbanization) inevitably leads to a decrease in global arthropods. The diversity and variation in invertebrate diet influence the food composition of birds, especially species living in rapidly changing environments, such as the Tibetan Plateau. However, little is known of the seasonal variation in invertebrate diet in response to environmental changes. Here, we characterized the invertebrate diet composition in pre- and post-breeding black-necked crane (Grus nigricollis) using fecal metabarcoding. We identified 38 invertebrate genera; the top three were Tipula (82.1% of relative abundance), Ceramica (3.0%), and unclassified_Hymenoptera (2.5%), with Tipula predominated the diet in both seasons. We also observed 20 and 16 unique genera in the pre- and post-breeding periods, and the genera composition was distinct between seasons (R = .036, p = .024). In pre-breeding, black-necked cranes tended to consume more diverse foods, and individual cranes exhibited greater heterogeneity at the genus level. At the genera and species level, pre-breeding black-necked cranes showed a wider dietary niche than post-breeding cranes. We observed season-specific features, with Tipula (common crane fly) and Stethophyma (grasshoppers) being enriched in the post-breeding period and Ceramica (moth) being more abundant in the pre-breeding period. Three Tipula species had the greatest importance in discriminating between seasonal diets. This study demonstrated a seasonal pattern of invertebrate diet in the black-necked crane, suggesting diet composition in response to resource and species availability. These results elaborate on the foraging ecology of highland birds and can inform the management of black-necked crane conservation.

Impact of Seasonal Variation in Pasture on Rumen Microbial Community and Volatile Fatty Acids in Grazing Yaks: Insights from High-Altitude Environments.

The environment is one of the most important factors influencing the variation and diversity of the host gut microbiome in plateau areas. It is well-established that dietary variations substantially alter the rumen microbiota. However, there is limited research on the response of the rumen microbiota of grazing yaks to changes in seasonal diet composition under high-altitude environments. This study investigates the seasonal variations in rumen fermentation parameters, bacterial, and fungal communities in yaks, with a focus on the cold and warm seasons. Quantitative data revealed that in the cold season, yaks had an increased acetic acid proportion (p < 0.05) and acetic acid/propionic acid ratio (p < 0.05) compared to the warm season. The relative abundance of Bacteroidetes and Firmicutes were 64.67% and 25.82% in the cold season, respectively, and 66.77% and 26.87% in the warm season. The fungal community showed a higher abundance of Ascomycetes (58.72% to 76.91%) and Neocallimastigomycota in the cold season. These findings highlight the adaptation mechanisms of yaks to seasonal dietary changes and their implications for optimizing yak husbandry practices.

Seasonal Diet Change of the Florida Harvester Ant (Pogonomyrmex badius) and Competition with the Red Imported Fire Ant (Solenopsis invicta)

Seasonal Diet Change of the Florida Harvester Ant (Pogonomyrmex badius) and Competition with the Red Imported Fire Ant (Solenopsis invicta)

Understanding the seasonal dietary patterns of the golden jackal (Canis aureus) for conservation implications in the Hirpora Wildlife Sanctuary, Western Himalayas

Wild canids form an important component of the ecosystem but are generally less studied and least prioritized for conservation. Diet is fundamental for effective management and exhibits the role of a species in an ecosystem. Golden jackal (Canis aureus, Linnaeus, 1758), a medium-sized canid species is known for opportunistic and omnivorous foraging behavior. This research investigates the feeding ecology of golden jackals within the Hirpora Wildlife Sanctuary, Western Himalayas. From August 2020 to July 2022, trails (n=9; 1.5-5.5km) were walked seasonally (once per month) to collect fecal samples (n=128) for investigation of seasonal diet composition and dietary niche breadth and biomass consumption of prey items by golden jackal. The association between the coefficient of digestibility value and food items was assessed using the Pearson correlation. We also conducted PCA to understand contribution of major dietary items. Scat analysis revealed that jackals feed on both animal and plant matter. Animal matter constituted most of the diet, encompassing small mammals and domestic livestock, insects, and birds. Rodents emerge as the dominant dietary item, maintaining consistent prevalence year-round. Livestock carrion, notably domestic sheep formed a significant component across all seasons, with maximal consumption observed in summer. Notably absent from the jackals' diet were traces of threatened mountain ungulates. Domestic sheep emerged as the primary contributor (33.4%) to the overall biomass consumed, highlighting the jackals' interaction with human-associated food resources. The research unveils an overall dietary niche breadth of 0.38, indicating a low degree of dietary diversity. Seasonal analysis indicates heightened dietary overlap in the autumn-summer transition, with rodents, domestic sheep, and birds being major contributors to this overlap. The findings underscore the adaptability of golden jackals to diverse food resources in a seasonal environment. This study provides foundational insights into the dietary ecology of jackal crucial for its conservation and management strategies in the ecologically fragile ecosystem. The finding gives a hint at the role jackals can play in regulating rodent populations and contributing to environmental cleanliness by scavenging.

Seasonal variability in the feeding ecology of an oceanic predator

Complementary approaches (stomach contents, DNA barcoding, and stable isotopes) were used to examine seasonal shifts in the feeding ecology of an oceanic predator, yellowfin tuna (Thunnus albacares, n = 577), in the northern Gulf of Mexico. DNA barcoding greatly enhanced dietary resolution and seasonally distinct prey assemblages were observed for both sub-adults and adults. In general, diet was characterized by ommastrephid squids and exocoetids in spring, juvenile fishes (i.e., carangids and scombrids) in summer, migratory coastal fishes during fall, and an increased consumption of planktonic prey (e.g., amphipods) in winter. Seasonal variability in bulk stable isotope values (δ13C, δ15N, and δ34S) was also observed, with low δ15N values and high δ34S values during late summer/early fall and high δ15N values (low δ34S) during late winter/early spring. Bayesian stable isotope mixing models corroborated seasonal diet shifts, highlighting the importance of oceanic nekton in spring/summer, coastal nekton during fall, and oceanic plankton during winter. Seasonal shifts in diet appeared to be influenced by prey reproductive cycles, habitat associations, and environmental conditions. Findings highlight the complex food web dynamics supporting an opportunistic oceanic predator and the importance of seasonal cycles in prey availability to predator resource utilization in open-ocean ecosystems.

Marsh Harrier Circus aeruginosus diet and hunting habitat selection in the breeding season: implications for lowland breeding waders

ABSTRACT Capsule A temporal mismatch between peak Marsh Harrier hunting activity and wader chick availability means that in most years waders contribute a negligible component of Marsh Harrier breeding season diet when nesting adjacent to lowland grassland, despite a spatial overlap in their habitat use. Aims To examine the potential for conservation conflict with breeding waders by assessing spatio-temporal patterns in Marsh Harrier hunting activity and examining historical and recent data on Marsh Harrier breeding season diet. Methods We monitored Marsh Harrier hunting behaviour in relation to time-in-season and habitat characteristics, and examined nest hatching records of Marsh Harrier and wader nests (Northern Lapwing Vanellus vanellus, Common Redshank Tringa totanus, Black-tailed Godwit Limosa limosa) for evidence of temporal overlap between hunting peaks and predicted wader chick availability. We also recorded prey provisioning to Marsh Harrier broods using nest cameras (2013–2015) and combined this with Marsh Harrier diet studies across Europe from 1942 to 2016. Results Wader adults and chicks contributed only a small proportion (average 1.5%) to the diet of Marsh Harriers nesting adjacent to breeding wader habitats between 1942 and 2016. This was likely due to a temporal mismatch in the peak of harrier hunting and the predicted availability of wader chicks in most years, despite a spatial overlap in habitat use between wader chick-rearing and Marsh Harrier hunting. Conclusion Conservation conflict between breeding Marsh Harriers and waders on lowland grassland is likely to be minimal in most years, with little evidence of waders as harrier prey items. However, harrier hunting activity increases through the breeding season, driven by the timing of their nesting and chick-rearing, and hunting activity was highest over field centres, where waders breed, so later-nesting wader pairs are still at risk. Wader conservation strategies that encourage survival of early wader nests may therefore limit predation and conservation conflict with Marsh Harriers.

Seasonal diet partition among top predators of a small island, Iriomote Island in the Ryukyu Archipelago, Japan

Small islands tend to lack predators because species at higher trophic levels often cannot survive. However, two exceptional top predators—the Iriomote cat Prionailurus bengalensis iriomotensis, and the Crested Serpent Eagle Spilornis cheela perplexus—live on the small Iriomote Island in the Ryukyu Archipelago. To understand how these predators coexist with limited resources, we focused on their seasonal diets between which conflicts are considered to occur. To compare the diets, we used DNA metabarcoding analysis of faecal samples. In the summer, we identified 16 unique prey items from Iriomote cat faecal samples and 15 unique prey items from Crested Serpent Eagle faecal samples. In the winter, we identified 37 and 14, respectively. Using a non-metric multidimensional scaling and a permutational multivariate analysis of variance, our study reveals significant differences in the diet composition at the order level between the predators during both seasons. Furthermore, although some prey items at the species-to-order level overlapped between them, the frequency of occurrence of most prey items differed in both seasons. These results suggest that this difference in diets is one of the reasons why the Iriomote cat and the Crested Serpent Eagle are able to coexist on such a small island.

Invasive wild pig (Sus scrofa) diets on barrier islands in the southeastern United States.

Biological invasions are a leading cause of reductions in global biodiversity. Islands are particularly sensitive to invasions, which often result in cascading impacts throughout island communities. Wild pigs (Sus scrofa) are globally invasive and pose threats to numerous taxa and ecosystems, particularly for islands where they have contributed to declines of many endemic species. However, the impacts of wild pig diet on the flora and fauna remain understudied in many island systems. We used DNA metabarcoding of wild pig fecal samples to quantify the seasonal diet composition of wild pigs on three barrier islands in the southeastern United States. Wild pigs exhibited a diverse diet dominated by plants, but also including marine and terrestrial animals. The diet composition of plants varied seasonally and between islands. Consumption of invertebrates also changed seasonally, with a shift to coastal invertebrates, particularly crabs, in spring and summer. Vertebrates were found in <10% of samples, but spanned broad taxa including amphibians, fish, mammals, and reptiles. Species consumed by wild pigs indicate that wild pigs use a variety of habitats within barrier islands for foraging, including maritime forests, saltmarshes, and beaches. An observed shift to beach foraging during sea turtle nesting season suggests wild pigs have potential to hinder nesting success on islands without established management programs. These findings provide insight into the diverse diets of wild pigs on barrier islands and highlight the need for removal of wild pigs from sensitive island ecosystems because of their potential impacts to native plant and animal communities. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Shift in piscivory by salmonids following invasion of a minnow in an oligotrophic reservoir

AbstractPredation can play an important role in structuring ecological communities, and predator–prey dynamics can be altered following the introduction of new species. An unauthorized introduction of redside shiner (Richardsonius balteatus) into reservoirs in the Upper Skagit River, Washington, USA created concern that a consequent shift in predator–prey dynamics in the reservoirs could reduce recruitment and production of native salmonids in the basin. We estimated predation mortality in Ross Lake on nonnative redside shiner and juvenile native salmonids to evaluate the potential role of predation in regulating these populations and limiting survival of native species of concern. We used bioenergetics modelling and stable isotope analysis combined with directed field measurements of growth, seasonal diet and thermal experience of piscivorous salmonids to quantify their consumption demand on prey fishes to evaluate the relative magnitude of predation mortality on invasive redside shiners and native salmonids. While redside shiner are the dominant prey fish species in Ross Lake, the modest biomass of native salmonids consumed could translate into substantial mortality, the magnitude of which depended on the timing and size at which prey fishes were eaten. This information provides important context for how nonnative species may indirectly impact native species through shared predation (apparent competition) and can inform conservation decisions surrounding nonnative species control, sustainability of native salmonids and introductions of anadromous fishes.

Seasonal Diet Composition of Goitered Gazelle (Gazella subgutturosa) in an Arid and Semi-Arid Region of Western China.

Global climate change, habitat fragmentation, and human interference have resulted in a significant, ongoing decline in the population of goitered gazelles. Effective conservation strategies require an understanding of resource requirements of threatened species, such as dietary needs. Therefore, we aimed to elucidate the food composition and seasonal dietary changes of goitered gazelles through microhistological analyses of fresh feces. Fabaceae (11.5%), Gramineae (9.4%), Chenopodiaceae (20.2%), Asteraceae (10.1%), and Rosaceae (19.5%) formed the primary dietary components of goitered gazelle. Additionally, Krascheninnikovia arborescens (13.4%) and Prunus sibirica (16.3%) were identified as the key forage plants. Forbs (50.4%) were the predominant plants for grazing throughout the year, particularly in the spring (72.9%). The proportion of trees in the diet was highest in the autumn (36.7%) and comparatively lower in other seasons. Furthermore, the proportions of shrubs (22.0%) and graminoids (14.8%) both reached their peaks in the winter. Our findings indicate that goitered gazelles strategically forage seasonally to cope with resource bottlenecks, enhancing their adaptability to arid and semi-arid habitats. Our study provides essential ecological information for the conservation of goitered gazelles and emphasizes the importance of dietary studies of species of ecological significance in environmentally sensitive areas.

Eco-evolutionary dynamics of gut phageome in wild gibbons (Hoolock tianxing) with seasonal diet variations

It has been extensively studied that the gut microbiome provides animals flexibility to adapt to food variability. Yet, how gut phageome responds to diet variation of wild animals remains unexplored. Here, we analyze the eco-evolutionary dynamics of gut phageome in six wild gibbons (Hoolock tianxing) by collecting individually-resolved fresh fecal samples and parallel feeding behavior data for 15 consecutive months. Application of complementary viral and microbial metagenomics recovers 39,198 virulent and temperate phage genomes from the feces. Hierarchical cluster analyses show remarkable seasonal diet variations in gibbons. From high-fruit to high-leaf feeding period, the abundances of phage populations are seasonally fluctuated, especially driven by the increased abundance of virulent phages that kill the Lachnospiraceae hosts, and a decreased abundance of temperate phages that piggyback the Bacteroidaceae hosts. Functional profiling reveals an enrichment through horizontal gene transfers of toxin-antitoxin genes on temperate phage genomes in high-leaf season, potentially conferring benefits to their prokaryotic hosts. The phage-host ecological dynamics are driven by the coevolutionary processes which select for tail fiber and DNA primase genes on virulent and temperate phage genomes, respectively. Our results highlight complex phageome-microbiome interactions as a key feature of the gibbon gut microbial ecosystem responding to the seasonal diet.

Seasonal Diet Changes and Trophic Links of Cold-Water Fish (Coregonus albula) within a Northern Lake Ecosystem

The seasonal feeding patterns of the cold-adapted fish, Coregonus albula, are poorly studied in high-latitude lakes but could provide insight for predicting the effects of global warming. We examined vendace’s diet composition, traced the carbon and nitrogen isotope ratios from producers to consumers in the food web, and estimated vendace’s trophic position in a subarctic lake (the White Sea basin). Results showed the vendace to be a typical euryphagous fish, but clear seasonal differences were found in the relative importance of plankton and benthos in the diet. The vendace consumed primarily benthic amphipods in the summer, planktonic cladocerans in the autumn, and copepods in the winter–spring (under ice); larvae of aquatic insects were the second-most important food items throughout the year. Because of the substantial proportion of fish embryos in its diet, the vendace had a trophic position similar to that of a predatory fish (perch). The Bayesian food source-mixing model revealed that the majority of vendace energy derives from planktonic copepods. The dominant Cyclops had the lowest carbon isotope values, suggesting a carbon-depleted diet typical for methanotrophic bacteria, as its probable food source was in a lake under ice. Understanding the feeding patterns of vendace provides information to better predict the potential biotic effects of environmental change on lake ecosystems.

Variation of parental and chick diet in opportunistic insectivorous European Bee-eaters

Variation of parental and chick diet in opportunistic insectivorous European Bee-eaters

Trophic ecology of the demersal predator Brazilian flathead Percophis brasiliensis (Percophidae) in a coastal upwelling ecosystem, SW Atlantic

Abstract Upwellings are important oceanographic processes that induce several changes in marine ecosystems, including in the benthic-pelagic coupling (BPC) that plays a major role in coastal areas. However, there is little available information about the possible effects of coastal upwellings on the trophic role of predators and in the BPC. Thus, here we investigate possible seasonal and ontogenetic changes in the trophic interaction of a demersal predator, the Brazilian flathead Percophis brasiliensis, from an upwelling ecosystem. Sampling was carried out for one year during two coastal upwelling events. Based on stomach content analysis (SCA) were recorded seasonal diet shifts, probably driven by coastal upwellings, leading to an increase in pelagic prey and changing the trophic coupling pathways. Stable isotope analysis revealed that isotopic niche decreased with the body size, as well as the values of the Levins’ index. Also, significant, and positive relationships were observed between δ13C and δ15N versus total length. Our results showed that the demersal predator has a relevant trophic role in the BPC which is probably influenced by coastal upwellings.

Seasonal dynamics of gut microbiome: A study of multi-kingdom microbiota of earthworm gut in an urban park

Seasonal dynamics of gut microbiome: A study of multi-kingdom microbiota of earthworm gut in an urban park