Trophic cascades: linking ungulates to shrub-dependent birds and butterflies

Great Tits’, Parus major (Passeriformes, Turdidae), Diet in Transformed Forest Ecosystems of Northeastern Ukraine

The diet spectrum of the great tit (Parus major L., 1758) was studied in transformed forests of northeastern Ukraine. Four forest ecosystems were surveyed: four model sites in oak woodlands and in a pine–oak forest with different stages of recreational digression. Forty-seven taxa of invertebrates (n = 325) were detected in the ration of great tit chicks. Insecta (72.4%): Lepidoptera (seven families, 35.9%), Hymenoptera (two families, 21.0%), Diptera (seven families, 2.7%) and Coleoptera (four families, 1.8%) were among them. In terms of the qualitative composition of invertebrates (20 species, 42.6%) and the proportion of seized food objects (159 objects), phytophages prevailed. The food composition of great tit chicks was the most similar in territories MS1 and MS4. It contained six common taxa for these territories (Stugren–Radulescu Index = 0.7, Jaccard = 0.2, Sorensen = 0.3).

Usually hated, sometimes loved: A review of wild ungulates' contributions to people

Nature's contributions to people (NCP) may be both beneficial and detrimental to humans' quality of life. Since our origins, humans have been closely related to wild ungulates, which have traditionally played an outstanding role as a source of food or raw materials. Currently, wild ungulates are declining in some regions, but recovering in others throughout passive rewilding processes. This is reshaping human-ungulate interactions. Thus, adequately understanding the benefits and detriments associated with wild ungulate populations is necessary to promote human-ungulate co-existence. Here, we reviewed 575 articles (2000-2019) on human-wild ungulate interactions to identify key knowledge gaps on NCP associated with wild ungulates. Wild ungulate research was mainly distributed into seven research clusters focussing on: (1) silvicultural damage in Eurasia; (2) herbivory and natural vegetation; (3) conflicts in urban areas of North America; (4) agricultural damage in Mediterranean agro-ecosystems; (5) social research in Africa and Asia; (6) agricultural damage in North America; (7) research in natural American Northwest areas. Research mostly focused on detrimental NCP. However, the number of publications mentioning beneficial contributions increased after the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services conceptual framework was implemented. Human-ungulate interactions' research was biased towards the Global North and Cervidae, Suidae and Bovidae families. Regarding detrimental NCP, most publications referred to production damage (e.g. crops), followed by biodiversity damage, and material damage (e.g. traffic collisions). Regarding beneficial NCP, publications mainly highlighted non-material contributions (e.g. recreational hunting), followed by material NCP and regulating contributions (e.g. habitat creation). The main actions taken to manage wild ungulate populations were lethal control and using deterrents and barriers (e.g. fencing), which effectiveness was rarely assessed. Increasing research and awareness about beneficial NCP and effective management tools may help to improve the conservation of wild ungulates and the ecosystems they inhabit to facilitate people-ungulate co-existence in the Anthropocene.

The Morphological Changes of Moths on Nakajima Island, Hokkaido, Japan

Overgrazing by large mammalian herbivores has led to significant adverse impacts on ecosystems globally. Insects are often a key taxon affected by large herbivores because the plants that are grazed provide crucial food and habitat. By changing vegetation, overgrazing by herbivores could affect aspects of insect morphology, including through changes to larval development due to reduced food availability, and adult dispersal ability due to habitat fragmentation. We investigated the wing morphology of moth species in two contrasting sites at Lake Toya in Hokkaido, Japan. We compared moths on Nakajima Island where deer are overabundant, with moths from the lakeshore 3 km away where deer are far less abundant. We compared forewing size and aspect ratio (length/width) of 13 moth species from both lakeshore and island sites. Four species, three of which were herb-feeding generalists, had significantly smaller wings on the island compared with the lakeshore. Seven species demonstrated a reduction in wing aspect ratio, whereas one species, the largest we measured, showed an increase in wing aspect ratio. We suggest that these morphological changes could be induced by overgrazing by deer (i.e., a reduction in moth host plant biomass and quality) and/or the isolation of moth populations on Nakajima Island. Further work is needed to reveal how these confounded but potentially interacting effects contribute to the morphological changes we found in the moths on the island. Our results show that habitat isolation and overabundance of deer populations can affect moth wing morphology, with potential implications for their population dynamics and community structure.

Opposing deer and caterpillar foraging preferences may prevent reductions in songbird prey biomass in historically overbrowsed forests

Overbrowsing by ungulates decimates plant populations and reduces diversity in a variety of ecosystems, but the mechanisms by which changes to plant community composition influence other trophic levels are poorly understood. In addition to removal of avian nesting habitat, browsing is hypothesized to reduce bird density and diversity through reduction of insect prey on browse‐tolerant hosts left behind by deer. In this study, we excluded birds from branches of six tree species to quantify differences in songbird prey removal across trees that vary in deer browse preference. Early in the breeding season, birds preyed on caterpillars at levels proportional to their abundance on each host. Combining these data with tree species composition data from stands exposed to experimentally controlled deer densities over 30 years ago, we tested whether overbrowsing by white‐tailed deer reduces prey biomass long after deer densities are reduced. Our analysis predicts total prey availability in the canopy of regenerating forests is fairly robust to historic exposure to high deer densities, though distribution of prey available from host species changes dramatically. This predicted compensatory effect was unexpected and is driven by high prey abundance on a single host tree species avoided by browsing deer, Prunus serotina. Thus, while we confirm that prey abundance on host trees can act as a reliable predictor for relative prey availability, this study shows that quantifying prey abundance across host trees is essential to understanding how changes in tree species composition interact with ungulate browse preference to determine prey availability for songbirds.