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Replacement of natural forests with plantations is causing forest loss and fragmentation worldwide. There is a great need for conservation and restoration of fauna in these fragmented forests, particularly those with special ecological functions, such as fruit-eating birds. In this 3-year study, we explored the relative importance of landscape-level and local factors for the richness and abundance of fruit-eating birds in broad-leaved forest patches scattered within a coniferous plantation in Japan. As local factors of remnant forests we included fleshy fruit availability and stand structural attributes, and then analyzed how the relative importance of these factor varies between the breeding (May–August) and non-breeding (September–December) seasons and among three bird size classes. Our results provide new insights into seasonal variations in the factors associated with bird richness and abundance and demonstrate the importance of fruit availability in the remnant forest patches. The main factors showing positive associations with bird richness/abundance were stand structural attributes (e.g., tree basal area) and landscape variables (e.g., proportion of broad-leaved forest) during the breeding season, whereas it was fruit availability during the non-breeding season, when migrating birds are dominant. We detected only minor variations in the associated factors among the three size classes. Thus, preserving continuous mature forests is of great importance for conserving breeding communities of fruit-eating birds, and maintaining fruit availability is an effective approach for supporting migrating birds during the non-breeding season. These findings are applicable to forest management aimed toward biodiversity conservation in regions being replaced or to be replaced by plantations, such as in many areas of temperate East Asia.

Forest loss and degradation can impact on ecosystem functions. Decomposition of vertebrate carcasses is an important ecosystem function in forests, and burying beetles and scavenging vertebrates is known to contribute to the provision of this function in forests. However, the relative importance of burying beetles and scavenging vertebrates in the removal of vertebrate carcasses has rarely been explored in terms of the impact of forest loss and degradation. Here, we experimentally placed mouse carcasses on forest floors to investigate burial and removal rates by forest animals during a 7-day period at 31 sites (natural broad-leaved forests and conifer plantations in an urban/agricultural matrix) in central Japan. Ninety-six percent of dead mice disappeared with 7 days of being placed on the forest floor. Rates of carcass disappearance increased with forest area surrounding the study sites. Field observations and camera trapping showed that two species of Nicrophorus burying beetles and six species of scavenging vertebrates contributed to the carcass burial and removal. Burial rates by beetles increased with forest area, while removal rates by vertebrates decreased with forest area. Model comparisons showed that the area of both natural forests and plantations surrounding the study sites influenced burial and removal rates. Therefore, forest loss influenced the disappearance rates of vertebrate carcasses. Different responses to forest loss between burying beetles and scavenging vertebrates could maintain the carcass burying/removing function at a landscape level.