Unmanaged forest and bird community: a study in north-western Lombardy

ABSTRACTAimSeasonality governs species composition at a given place and time. However, the effects of climate and land‐use change can vary by season, altering species composition. These changes can lead to a loss of distinct seasonal community composition, representing a novel form of biotic homogenisation. We ask if breeding and winter bird communities are becoming more similar over time. If so, is homogenisation occurring more rapidly in winter than in the breeding season, and has the presence of individual species changed between seasons?LocationNortheastern United States.Time Period1989–2019.Major Taxa StudiedTwo hundred thirty‐eight bird species.MethodsWe use data from The National Audubon Society's Christmas Bird Count and the North American Breeding Bird Survey to test if winter and breeding bird communities have become more similar (homogenised). We evaluate this change using the Sørensen dissimilarity index, and its components of turnover (species replacement) and nestedness (a subset of a more species rich community) and describe the mechanism in which the seasonal winter and breeding bird communities are changing.ResultsWe found that winter and breeding bird communities are homogenising, driven by significant decrease in turnover and a marginal decrease nestedness. When viewing breeding and wintering communities separately, we observe different trends. Breeding communities are becoming more unique with decreasing turnover and nestedness. Winter communities are becoming more similar to each other, with decreasing turnover and nestedness. More breeding species are declining and species that are typically found in the winter and year‐round residents are the main contributors to the homogenisation between seasons.Main ConclusionsWe show for the first time homogenisation between winter and breeding bird communities over time across the northeastern United States. This insight into how individual species are faring between seasons, and how they impact community structure, can be used when implementing conservation measures for maintaining ecological functioning and integrity.

Comparison of breeding bird and vegetation communities in primary and secondary forests of Great Smoky Mountains National Park

Environmental management agencies make efforts to reduce pollution loading in streams and rivers by promoting vegetated buffer zones between human activity and water. Most of these efforts do not mesh water quality-based buffer zone width requirements with conservation and wildlife values, specifically, the use of these riparian forest corridors for wildlife dispersal between habitats in highly fragmented landscapes. Forest interior birds are of the most concern to management in riparian forests due to their population declines across much of their breeding range. This dissertation investigates the role that landscape-level and habitat-level factors play on the presence of breeding birds in riparian forests, particularly the landscape and habitat factors that are influenced by human-caused fragmentation. This study describes research at the Ray Roberts Greenbelt, Denton, Texas, that explores the relationships between the landscape and forest habitats of the Greenbelt with its breeding bird community. The major findings of this study are that bird communities in the corridor forests are associated with a greater array of factors than are bird communities in patches, suggesting that the birds of patch forests are somewhat insulated from landscape-scale effects. Also, habitat values can be maintained in corridors, but there does not seem to be a significant relationship between the bird communities and the habitat. Forest factors are the primary influences (as inferred from the number of associations and the relative strength of these associations) on the bird communities of the Ray Roberts Greenbelt. Thresholds of richness or abundance in the amount of forest as compared with the forest interior bird community suggest that patches are better than corridors to support this community, and that the more interior forest available, the better for forest interior birds. The suggested minimum amount of forest derived from these thresholds is 35% of the amount of forest within 1 kilometer of any given part of the Greenbelt. Thresholds in forest width for avian communities suggest a minimum width of 200 m for any corridor. Thresholds in distance from interior forest suggest that the forest interior bird community can be best supported by shorter corridors that connect larger patches, with a suggested maximum corridor length of 125 m.

We inventoried breeding and wintering bird communities in four treatments of temperate rainforest on Prince of Wales Island, southeast Alaska during 1991-1992 and 1992-1993. The four forest treatments sampled included: (1) young growth (20 years) originating from clearcut logging with no silvicultural modification (non-modified), (2) young growth (20 years) precommercially thinned along uniformly-spaced thinning grids (thinned), (3) young growth (20 years) with gaps in the overstory canopy created by felling trees in 0.05-ha openings (gapped), and (4) virgin old growth (≥ 150 years). Of 16 common breeding bird species observed, six showed significant responses to young-growth modifications. One species was more abundant and two species were less abundant in thinned sites, while one species was more abundant and two species were less abundant in gapped sites than at least one of the other treatments. None of the three common wintering species of birds observed was influenced by young-growth modification. Breeding bird communities, in general, were less similar between young- and old-growth treatments than among young-growth treatments. Three of the 16 common breeding bird species were more abundant in old growth than each of the young-growth treatments and one uncommon species was detected almost exclusively in old growth during both the breeding and wintering seasons. Four other breeding bird species were more abundant in young-growth treatments than in old growth. Higher use of old growth by wintering birds was related to winter severity. To enhance habitat for wintering and breeding birds we recommend: (1) thinning young growth along variable-spaced grids to create additional canopy layers and improve snow-intercept properties of young growth for canopy-foraging birds, (2) retention of old-growth clumps in clearcuts for bird species associated with old-growth structure, and (3) long-term conservation of old-growth temperate rainforest for breeding and wintering birds positively associated with old growth.

The Samcheok forest fire of April 2000 was the biggest stand-replacing fire recorded in Korea, and led to the largest-scale salvage logging operation (performed until 2005) ever implemented. We investigated the effects of the treatments performed after the fire on the breeding bird community in 2002–2005 (the management period) and 2006–2008 (the post-management period). A total of 75 line transect surveys resulted in 660 detections of 54 species in undisturbed stands (CO), in burned and naturally restored stands (NI), and in burned and logged stands (IT). Four species (Parus major, Aegithalos caudatus, Dendrocopos kizuki, and Parus ater) were identified as indicator species in CO which showed no temporal changes in bird communities and habitat structure. Among the various stand treatments, the standardized species richness was highest in CO (11.6 ± 4.6 species/transect in 2002–2005, 12.1 ± 3.5 in 2006–2008), and this richness did not change over time. On the other hand, low richness was observed in NI (6.8 ± 2.6 in 2002–2005, 9.6 ± 2.3 in 2006–2008), and the lowest richness was seen in IT (5.0 ± 2.4 in 2002–2005, 6.1 ± 1.8 in 2006–2008), but both of these increased over time. Although the bird abundances in NI and IT were lower than those in CO (38.0 ± 27.7 birds/transect in 2002–2005, 31.3 ± 10.9 in 2006–2008), the abundances in NI (15.1 ± 8.6 in 2002–2005, 17.6 ± 11.4 in 2006–2008) and IT (11.7 ± 8.3 in 2002–2005, 10.0 ± 4.6 in 2006–2008) were not significantly different. There was no significant difference in abundance between time periods for any of the stand treatments. These results imply that NI (i.e., no salvage logging) allows greater bird richness but not abundance to be recovered compared to IT. No indicator species was consistently present in NI throughout the two time periods covered due to the rapid regrowth of vegetation, but four open-habitat dwellers (Falco tinnunculus, Phoenicurus auroreus, Emberiza cioides, and Sturnus cineraceus) colonized IT during the post-management period. The bird assemblage in IT, as assessed by canonical correspondence analysis, shifted to open habitats, while the avifauna in NI became similar to that in CO over time. While post-fire treatment can provide new colonization opportunities for open-habitat dwellers, the slow colonization process, the low species richness, and the low bird abundance observed in large areas of IT indicate that post-fire treatment using salvage logging inhibits the restoration of forest bird communities by producing a poorer breeding bird community that is very different from the original one. Based on these lessons from the response to the Samcheok forest fire, we suggest that preserving as much of the disturbed forest as possible is essential, and that the current approach to post-fire treatment—intensive salvage logging—needs to be revised to ensure the effective restoration of breeding bird communities in disturbed temperate pine forests.

We examined the relative importance of riparian vs. upland habitats to breeding birds by comparing species abundance, richness, and similarity of bird communities in managed Douglas-fir forests in western Washington State, USA. We also examined whether forested buffer strips along second- and third-order streams effectively maintain the pre-logging riparian breeding bird community by comparing species abundance, richness, and turnover among three treatments: (1) unharvested controls; (2) sites that were clear-cut, leaving a narrow (∼14 m) forested buffer on both sides of the stream; and (3) sites that were clear-cut, leaving a wide (∼31 m) forested buffer along both sides of the stream. Deciduous trees, berry-producing shrubs, and other deciduous shrubs less common in adjacent upland forest characterized streamside zones. Despite different vegetation features, riparian and upland habitats did not differ in any measures of bird species richness and composition. No species or species group was more abundant in the upland. Neotropical migrants, resident species, and species associated with deciduous trees and shrubs in forested habitats were more abundant in riparian habitats than in adjacent uplands. Total bird abundance and abundance of four species (American Robin [Turdus migratorius], Pacific-slope Flycatcher [Empidonax difficilis], Black-throated Gray Warbler [Dendroica nigrescens], and Winter Wren [Troglodytes troglodytes]) were higher in riparian habitats. Abundance of these riparian associates was correlated with percent cover of berry-producing shrubs and the number of deciduous trees in the canopy. We found that the number of breeding bird species on sites with narrow buffers increased from slightly fewer than controls before harvest to an average of 10 more species than controls after harvest, a change reflected in an average 20% increase in species turnover on narrow-buffer sites relative to controls. Total bird abundance did not differ between treatments and controls. Resident species, those species associated with shrubs in forested habitats and conifer trees, declined on both buffer treatments. Species associated with upland and riparian forests (Black-throated Gray Warbler, Golden-crowned Kinglet [Regulus satrapa], and Brown Creeper [Certhia americana]) decreased in abundance on riparian buffer treatments relative to controls, whereas species associated with open, shrubby habitats (Dark-eyed Junco [Junco hyemalis], Cedar Waxwing [Bombycilla cedrorum], and Song Sparrow [Melospiza melodia]) increased in abundance on one or both riparian buffer treatments. High species turnover on narrow-buffer treatments indicated that buffers <14 m on each side of the stream did not maintain the pre-logging bird community. There was little difference in species turnover or species richness between the wide-buffer treatment and the control, indicating that a 30-m buffer on both sides of second-order and third-order streams maintains most of the pre-logging bird community in the first two years postharvest. The Black-throated Gray Warbler was the only riparian associate to decline on both the narrow- and wide-buffer treatments; its abundance was positively correlated with buffer width, and a buffer ≥45 m wide on each side of second- and third-order streams was needed to support populations at densities found on unharvested controls. To maintain the entire breeding bird community associated with forested riparian habitats in the coastal Northwest, we recommend a minimum buffer of 45 m along both sides of second- and third-order streams. Habitat features such as deciduous trees (Alnus rubra and Acer macrophyllum) and berry-producing shrubs (especially Rubus spectabilis) appear to be important and should be maintained within forested riparian buffer strips. This study documents short-term effects of riparian treatments on the breeding bird community, which may take several years to respond to habitat manipulations. Thus, we recommend continued monitoring to assess long-term effects of buffer width reduction.

This article examines the bird community of a large reservoir and its surrounding area , located in the central part of a large city in the northern part of the steppe zone of Ukraine. The city, Krivoy Rog, has a population of over 700,000 people. Large areas of the city have undergone dramatic transformation. Industrial and and residential areas of the city are located around the reservoir. The shores of the reservoirs are subject to recreational loading. The natural landscape here is a combination of steppe habitats and scubland.. The material for this study was collected in the breeding seasons of 1996, 1999, 2012, 2015. The number and distribution of birds were determined by registrations of birds along transects. The diversity index, dominance and evenness of species distribution in the breeding bird communities were compared for different habitats and different years. In breeding season 73 bird species belonging to 15 orders were found on the territory of the reservoir. Of these, 62 species bred, and 11 more used the area for foraging but bred in adjacent habitats. 24 species were present in winter. The average density of the breeding birds per species increased from 1.8 ± 0.4 pairs/km of survey route in 1996 to 3.2 ± 0.8 pairs/km in 2015. The dominant species in the breeding bird communities were Passer montanus L., Sturnus vulgaris L., Parus major L., Fulica atra L., Podiceps cristatus L. In the period 1996–1999 the habitat conditions in the territory of the water reservoir changed. These changes were associated with mass recreation of city residents here. The changes resulted in a stressful situation for the habitats and the bird communities. The changes resulted in an imbalance in the development of the bird communities. Since 2012 the birds adapted to the new environmental conditions and formed a new community. By 2015, the species diversity of birds had increased, the degree of pressure on the dominant species and the species distribution of the species had leveled off. The number of bird species nesting in the habitats of the water reservoir had increased. Within the bird communities ground and cavity nesting birds were replaced by woodland-nesting species. Transformation of bird habitat had a decisive impact on the development of the community of nesting birds. The differences in ecological characteristics of the community of birds were expressed along the gradient of transformation of habitats: the proportion of ground-nesting species in the community fell, species diversity was reduced, the dominant species increased their pressure on the bird community and and the distribution of of species abundance became more uniform. Against the background of these changes, the diversity of breeding species increased in the tree plantations, as compared to transformed natural habitats. This is evidence, that the development of the bird communities in artificially created habitats and development of bird communities in transformed habitats takes place in different ways and in different directions.

Beech forests in the Italian peninsula are actively managed and they also support a high level of biodiversity. Hence, biodiversity conservation can be synergistic with timber production and carbon sequestration, enhancing the overall economic benefits of forest management. This study aimed to evaluate the effect of forest management regimes on bird communities in the Italian Peninsula during 2022 through audio recordings. We studied the structure, composition, and specialization of the breeding bird community in four managed beech stands (three even-aged beech stands aged 20, 60, and 100 years old, managed by a uniform shelterwood system; one uneven-aged stand, managed by a single-tree selection system) and one uneven-aged, unmanaged beech stand in the northern Apennines (Tuscany region, Italy). Between April and June 2022, data were collected through four 1-hour audio recording sessions per site, analyzing 5 min sequences. The unmanaged stand hosted a richer (a higher number of species, p &lt; 0.001) and more specialized (a higher number of cavity-nesting species, p &lt; 0.001; higher Woodland Bird Community Index (WBCI) values, p &lt; 0.001; and eight characteristic species, including at least four highly specialized ones) bird community, compared to all the managed forests; moreover, the latter were homogeneous (similar to each other). Our study suggests that the unmanaged beech forests should be a priority option for conservation, while in terms of the managed beech forests, greater attention should be paid to defining the thresholds for snags, deadwood, and large trees to be retained to enhance their biodiversity value. Studies in additional sites, conducted over more years and including multi-taxon communities, are recommended for a deeper understanding and generalizable results.

Effects of tree retention and woody biomass removal on bird and small mammal communities

Alternative silvicultural practices with variable retention improve bird conservation in managed South Patagonian forests

Hurricane Katrina impacts the breeding bird community in a bottomland hardwood forest of the Pearl River basin, Louisiana

The aim of this study was to examine the changes in breeding bird communities resulting from change in habitat structure caused by forestry. Research was conducted in a natural deciduous forest within the Pyoungchang national forest, Kangwon Province (N 37°27′, E 128°29′), in the Northeastern part of South Korea, from April to June, 1996. Three 8-ha areas with differing degrees of deforestation were selected for territory mapping of breeding bird communities. Vegetation characteristics, vertical structure of habitat (foliage height profile), and diameters at breast height (DBH) distribution were measured in each study area. The characteristics of the breeding bird communities and their niche relationships were surveyed. The relationships between habitat structure and breeding bird communities were also examined. The dominant tree species in the study area were Quercus mongolica, Ulmus davidiana, Acer mono and Fraxinus rhynchophylla. The vertical structure of the forest differed among the study areas. The number of trees per hectare, tree species diversity, and range of DBH decreased with the degree of forest cutting among the areas studied. Bird species diversity, breeding density, species richness, and guild structures also differed among study areas. The hole-nesting and canopyforaging guild was dominant in intact natural forest, whereas the bush-nesting and bush-foraging guild was found to be more prevalent at areas where a few trees had been felled. We found that the structure of a forest seems to be an important determining factor for a breeding bird community. Therefore, the interaction between the structure of a forest and its bird community should be considered in forest management for conservation of bird communities and their habitat.

Avian communities of managed and wilderness hemiboreal forests

Many recent studies have addressed the effects of patch size and isolation on bird communities in highly fragmented landscapes, but the importance of landscape composition in more forested landscapes remains poorly understood. The objectives of our study were (1) to determine the effects of two structurally and temporally distinct disturbance types (agriculture and silviculture) and extent of disturbance (percentage of disturbance within 1.0 km) on avian community structure within forested landscapes, and (2) to investigate underlying mechanisms responsible for associations between landscape composition and avian communities. Differences in microhabitat, microclimate, and nesting success among landscapes were examined as possible mechanisms. Breeding bird communities in central Pennsylvania (USA) were surveyed twice per year during 1997–1999 at 34 sites within contiguous mature forest, which represented a range of disturbance extent (4–59% nonforest cover within 1.0 km). Each site was in a forested landscape containing predominantly agricultural or silvicultural disturbances (n = 17 each). Our results indicate that type of disturbance within landscapes influenced bird community composition and relative abundance more than extent of disturbance. Compared to forests within landscapes disturbed by silviculture, forests within landscapes disturbed by agriculture, irrespective of the extent of disturbance, had fewer forest-associated species, long-distance migrants, forest-canopy and forest-understory-nesting species, and greater numbers of edge-associated species, including avian nest predators and Brown-headed Cowbirds (Molothrus ater). Fewer species and guilds were associated with the extent of disturbance within a landscape or interactions between disturbance type and extent. Abundances of edge-associated species, residents, and forest-canopy nesters increased with increasing amounts of disturbance within forested landscapes. Local variation in microhabitat and microclimate among landscapes did not explain observed differences in avian community structure. However, nesting success was greater and numbers of some avian and small mammalian nest predators were lower in stands within forested landscapes disturbed by silviculture than in forested landscapes disturbed by agriculture. Nesting success was not associated with the extent of a given disturbance type within landscapes. These results demonstrate that, even within forested landscapes, the types of disturbance can influence avian community structure and, thus, should be considered in conservation and forest management plans. In particular, agricultural disturbances within forested landscapes seemed to negatively affect bird communities in adjacent forests more than silvicultural disturbances. Both species richness and abundance of forest-associated species were greater on sites with higher levels of nesting success. Thus, differences in nesting success resulting from altered interactions between nest predators and nesting birds may be an important underlying mechanism of avian community structure and organization at the landscape scale.

Many recent studies have addressed the effects of patch size and isolation on bird communities in highly fragmented landscapes, but the importance of landscape composition in more forested landscapes remains poorly understood. The objectives of our study were (1) to determine the effects of two structurally and temporally distinct disturbance types (agriculture and silviculture) and extent of disturbance (percentage of disturbance within 1.0 km) on avian community structure within forested landscapes, and (2) to investigate underlying mechanisms responsible for associations between landscape composition and avian communities. Differences in microhabitat, microclimate, and nesting success among landscapes were examined as possible mechanisms. Breeding bird communities in central Pennsylvania (USA) were surveyed twice per year during 1997–1999 at 34 sites within contiguous mature forest, which represented a range of disturbance extent (4–59% nonforest cover within 1.0 km). Each site was in a forested landscape containing predominantly agricultural or silvicultural disturbances (n = 17 each). Our results indicate that type of disturbance within landscapes influenced bird community composition and relative abundance more than extent of disturbance. Compared to forests within landscapes disturbed by silviculture, forests within landscapes disturbed by agriculture, irrespective of the extent of disturbance, had fewer forest-associated species, long-distance migrants, forest-canopy and forest-understory-nesting species, and greater numbers of edge-associated species, including avian nest predators and Brown-headed Cowbirds (Molothrus ater). Fewer species and guilds were associated with the extent of disturbance within a landscape or interactions between disturbance type and extent. Abundances of edge-associated species, residents, and forest-canopy nesters increased with increasing amounts of disturbance within forested landscapes. Local variation in microhabitat and microclimate among landscapes did not explain observed differences in avian community structure. However, nesting success was greater and numbers of some avian and small mammalian nest predators were lower in stands within forested landscapes disturbed by silviculture than in forested landscapes disturbed by agriculture. Nesting success was not associated with the extent of a given disturbance type within landscapes. These results demonstrate that, even within forested landscapes, the types of disturbance can influence avian community structure and, thus, should be considered in conservation and forest management plans. In particular, agricultural disturbances within forested landscapes seemed to negatively affect bird communities in adjacent forests more than silvicultural disturbances. Both species richness and abundance of forest-associated species were greater on sites with higher levels of nesting success. Thus, differences in nesting success resulting from altered interactions between nest predators and nesting birds may be an important underlying mechanism of avian community structure and organization at the landscape scale.