Dead wood threshold values for the three-toed woodpecker presence in boreal and sub-Alpine forest

Predicting species' responses to habitat loss is a significant challenge facing conservation biologists. We examined the response of both European three-toed woodpecker subspecies Picoides tridactylus tridactylus and P. tr. alpinus to different amounts of dead wood in a boreal and a sub-Alpine coniferous forest landscape in central Sweden and Switzerland, respectively. Habitat variables were measured by fieldwork in forests with breeding woodpeckers (n=10+12) and in control forests without breeding woodpeckers (n=10+12) in the same landscape. Logistic regression analyses revealed steep thresholds for the amount of dead standing trees and the probability of three-toed woodpecker presence in both Sweden and Switzerland. The probability of the presence of three-toed woodpeckers increased from 0.10 to 0.95 when snag basal area increased from 0.6 to 1.3 m² ha⁻¹ in Switzerland and from 0.3 to 0.5 m² ha⁻¹ in central Sweden. In Switzerland, a high road network density was negatively correlated to the presence of woodpeckers (r=−0.65, p=0.0007). The higher volumes of dead wood in Switzerland, where population trends are more positive, than in central Sweden, where the population is declining, would suggest that the volumes of dead wood in managed forests in Sweden are too low to sustain three-toed woodpeckers in the long-term. In terms of management implications, we suggest a quantitative target of at least 5% of standing trees in older forests being dead over at least 100 ha large forest areas. This corresponds about to ?1.3 m² ha⁻¹ (basal area) or ?15 m³ ha⁻¹ (volume), still depending on site productivity.     

Specialised woodpeckers and naturalness in hemiboreal forests – Deriving quantitative targets for conservation planning

In many parts of the world’s forests, intensive management has resulted in habitat loss for several species. Among these, specialised woodpeckers (Aves: Picidae) have been affected negatively due to their high requirements for resources that are scarce in managed forests. We used the gradient of anthropogenic impact on forests in northern Europe’s Baltic Sea region to (1) assess the relationship between the presence of four focal woodpecker species and forest naturalness and (2) quantify their requirements regarding specific resources in four different areas (south-central Sweden, southern Sweden, Lithuania and northeastern Poland). This study focused on specialised woodpecker species of the Dendropicini tribe: the three-toed (Picoides tridactylus), middle spotted (Dendrocopos medius), white-backed (Dendrocopos leucotos) and lesser spotted (Dendrocopos minor) woodpeckers. The occurrence of these species in landscape units of 100 ha was generally related positively to the degree of forest naturalness and to the amounts of resources considered critical for the suitability of their respective habitats. For the middle spotted woodpecker, basal areas 1.0 m²/ha of large-diameter deciduous trees (DBH  40 cm) were associated with a high probability of occurrence (0.9). For the white-backed woodpecker, the same probability of occurrence was found for basal areas 1.4 m²/ha of deciduous snags (DBH  10 cm). Relationships between the occurrence of the three-toed and lesser spotted woodpeckers and snag abundance were more variable among study areas. The results suggest that specialised woodpeckers would benefit from an increase in the area of forest with natural properties. Moreover, they allow defining tentative quantitative targets for sustainable forest management.     

Seasonal variation in home-range size, and habitat area requirement of the lesser spotted woodpecker (Dendrocopos minor) in southern Sweden

Seasonal variation in home-range size and habitat area requirement of lesser spotted woodpeckers (Dendrocopos minor) were studied by radio-tracking in southern Sweden for 6 years. Home-range size did not vary between age-groups or sexes, but varied with season and decreased successively from 742 ha in winter (n=10), 355 ha in early spring (n=15), 103 ha in late spring (n=22) to 43 ha during nesting (n=10). The home-range in late spring (i.e. the 3–5 weeks preceeding egg-laying) represents the defended breeding territory. This included on average 39 ha of forest utilised for foraging (range 31–46 ha, n=15). Since food availability in late spring has a significant influence on reproductive success, and mortality is highest in this period, we regard this as an estimate of the habitat area requirement. This estimate is valid primarily for birds in southern Sweden, but circumstantial evidence indicate that the area requirement may not be grossly different in other areas with different forest types. For conservation of lesser spotted woodpeckers, management should focus on a minimum of 40 ha of forest dominated by deciduous trees, which may be fragmented over a maximum of 200 ha.     

Indicator species among resident forest birds - A cross-regional evaluation in northern Europe

In European forests, plants, fungi and invertebrates have been proposed as indicator species for assessing conservation value at the stand scale. To cover larger spatial scales, wide-ranging vertebrates could be added to that set of species. For resident forest birds, we (1) explored whether the occurrence of some species could be used to indicate high species richness and abundances, and (2) compared the results among four regions in the Baltic Sea drainage basin with a common species pool but different forest management intensities and varying proportions of deciduous and coniferous trees (south-central and southern Sweden, south-central Lithuania and northeastern Poland). Assemblages of deciduous forest birds in 100-ha landscape units were generally nested, suggesting that species richness within that group may be predicted based on the presence of a few species. Birds of coniferous forests, however, showed poorer conformity to nestedness in Sweden. Specialised species such as the middle spotted (Dendrocopos medius) and lesser spotted woodpeckers (D. minor) in deciduous forest and the three-toed woodpecker (Picoides tridactylus) in coniferous forest generally figured among the best indicators. In deciduous forest, there was high cross-regional consistency in the identity of the best indicators. Moreover, the sites where the best indicator was present also harboured higher relative abundances of most background species. For coniferous forest, however, such a relationship was not found. We conclude that an indicator species approach may be useful for resident birds of deciduous forests in hemiboreal Europe, emphasising that it should constitute one of many complementary tools for conservation management.     

Bird species richness in a Bornean exotic tree plantation: A long-term perspective

To provide sustainable income from forestlands, large areas in the tropics are planted with “agricultural” trees, such as oil palm and rubber, and “industrial” trees, such as Acacia mangium and Gmelina arborea. To examine how native forest birds use such plantations, we surveyed in 2005 the avifauna at Sabah Softwoods, a plantation in southeastern Sabah, Malaysian Borneo. We focused on A. mangium, Albizia (Paraserianthes falcataria), oil palm (Elaeis guineensis), and logged native forest, and compared our results to those of a study conducted at the same plantation in 1982. The number of forest species in the industrial groves did not change dramatically between 1982 and 2005, even though the trees had been cropped several times and the plantation was, by 2005, completely surrounded by cleared land and far removed from primary forest. However, as is common in logged or isolated forests throughout the world, certain primary forest groups (e.g., muscicapine flycatchers) have been extirpated from the entire plantation area. The industrial groves also lacked some larger species of kingfisher, woodpeckers, and canopy frugivores. Nevertheless, numerous primary forest taxa (ca. 50% of species) were found in mature industrial tree groves. Albizia attracted the most species of birds, followed closely by Acacia. Both tree types underpinned relatively complex secondary forests that attracted forest birds. In contrast, younger groves of Acacia and Albizia held mainly open country and scrub species. Oil palm, as a remarkably simple and unusual habitat, attracted few bird species. Sustained occurrence of forest birds in all groves of exotic trees at Sabah Softwoods was substantially enhanced by the relatively rich avifauna of the logged native forest remaining in substantial stands throughout the plantation.     

Effect of forest fragmentation on fruit and seed predation of the tropical dry forest tree Ceiba aesculifolia

Forests fragmentation reduces the density of natural plant populations forming patches of the remaining individuals. One of the biotic interactions that can be affected by forest fragmentation and is poorly studied is seed predation. We determined the effects of forest fragmentation on seed and fruit predation in Ceiba aesculifolia by comparing trees in continuous forest with trees in fragmented forest. We compared the following variables: (a) frequency of fruit predation by Collie’s squirrel (Sciurus colliaei) in each habitat; (b) frequency of the cotton-staining bug seed predator (Dysdercus, Orden Hemiptera) in each habitat; (c) the effect of seed predation on germination frequency and time; and (d) the effect of different life stages of Dysdercus on seed viability. In continuous habitat, 100% of the trees presented fruits with squirrel predation while only 34% of trees in fragmented habitats presented fruit predation. In continuous forest 27% of the trees contained fruits with the seed predator Dysdercus, while only 2% of the trees in fragmented forest presented Dysdercus. The initial weight of damaged seeds was greater than seeds that were not damaged indicating that seed predators select heavier seeds to feed upon. Frequency of seed germination was affected by different life stages; pre-adults decreased germination significantly more than nymphs and adults. Seed predation significantly increased the time it took for germination to occur. Our study shows that forest fragmentation significantly affects predation patterns of squirrels and cotton-staining bugs. Reduction of natural seed predators in forest fragments may have long-term consequences on forest structure and diversity.     

Landscape supplementation in adjacent savannas and its implications for the design of corridors for forest birds in the central Cerrado, Brazil

We examined landscape supplementation (sensu [Oikos 65 (1992) 169]) by forest birds along forest/savanna boundaries in central Brazil to: (1) verify the role of savanna vegetation in providing resources to forest bird communities; (2) suggest minimum amounts of savannas to be conserved within corridors, to provide adequate foraging habitat for forest birds outside reserves. Transect counts parallel (n=64) and perpendicular (n=64) to forests were conducted in eight savannas (cerrado sensu stricto) between February 2000 and January 2001. Patterns of species richness and abundance of birds in relation to distances from forests were examined using Generalised Linear Mixed Models. Omnivores were the most abundant birds foraging in savannas, followed by insectivores and frugivores. Landscape supplementation in savannas was proportional to the density of savanna vegetation. Also, it was higher in the breeding season than in the non-breeding period. These two patterns suggest that surrounding savannas play a major role in providing additional foraging areas for forest bird species. We suggest that the environmental policy currently protecting 20 m of gallery forests along each side of rivers be modified to include at least 60 m of savanna along these forests through central Brazil. The study suggests that appropriate conservation efforts should also encompass the surrounding matrix to which the home ranges of target species are expanded, and not only their major habitat.     

川西高山峡谷区6种森林枯落物的持水与失水特性

川西高山峡谷区森林较高的地表枯落物储量可能具有较好的水文生态效益,但缺乏研究关注。以川西高山峡谷区6种森林为对象,在雨季调查了不同森林地表枯落物的持水和失水特性。结果表明:(1)川西高山峡谷区林地枯落物蓄积量与最大持水量和有效拦蓄量呈显著正相关,林地枯落物蓄积量为6.90～17.49 t/hm~2,最大持水量为1.64～5.42 mm,最大持水率为138.18%～330.09%,有效拦蓄量为0.53～3.33 mm,有效拦蓄率为77.57%～203.02%。(2)相对其他森林,亮叶桦(Betula luminifera)-青麸杨(Rhus potaninii)林枯落物的持水性能最好,橿子栎(Quercus baronii)-白刺花(Sophora davidii)-黄栌(Cotinus coggygria)林枯落物的持水性能最差。(3)林地枯落物的累积持水量和累积失水量分别随浸泡时间和失水时间的增加呈对数形式变化,但枯落物吸水速率和失水速率分别与浸泡时间和失水时间呈显著的幂函数关系。川西高山峡谷区森林枯落物在雨季具有明显吸持拦蓄降雨的功能,且以亮叶桦-青麸杨林最好,研究结果为该区森林生态建设和生态效益评价提供了参考依据。     

Estimating occupancy of a data deficient mammalian species living in tropical rainforests: Sun bears in the Kerinci Seblat region, Sumatra

Tropical mammals represent some of the most threatened species, but also the least known because they tend to be difficult to study. To objectively evaluate the conservation status of these species, standardized methods are urgently required. The sun bear Helarctos malayanus is a case in point: it is cryptic, difficult to detect and consequently classified on the IUCN Red List as Data Deficient, and the highest priority for bear conservation research. In this study, we apply a detection/non-detection sampling technique using camera trap data with environmental covariates to estimate sun bear occupancy from three tropical forest study areas with different levels of degradation and protection status in Sumatra. Sun bear detections, and encounter rates, were highest in one of the primary forest study areas, but sun bear occupancy was highest in the degraded forest study area. Whilst, sun bears were recorded at a greater proportion of camera placements in degraded forest, these records were often on only one occasion at each placement, which greatly increased the final occupancy estimate. Primary forests with their large fruiting trees undoubtedly represent good sun bear habitat, but our results indicate that degraded forest can also represent important habitat. These forests should therefore not be considered as having limited conservation value and assigned to other uses, such as oil palm production, as has previously happened in Sumatra. Estimating occupancy between years will yield information on the population trends of sun bears and other tropical mammals, which can be used to provide more reliable conservation assessments.     

Landscape and habitat factors affecting cabot's tragopan Tragopan caboti occurrence in habitat fragments.

Cabot's tragopan Tragopan caboti is an endemic and endangered pheasant of the lower montane forests of southeastern China. The typical habitats of the tragopan have been seriously fragmented because of forest management for timber production and farmland reclamation in recent years. The effects of the fragment size and isolation on the distribution of the cabot's tragopan were studied in Wuyanling Natural Reserve. Thirty one habitat fragments (2.5-48.5 ha) surrounded by non-habitat sapling coniferous forests, in an intensively managed forested landscape, were surveyed over four seasons for the occurrence of cabot's tragopan. Five of the 31 fragments were occupied in all four seasons and nine were not occupied. Both landscape and habitat factors affected the occurrence of cabot's tragopan, with landscape factors having the greatest effect. Large and less isolated habitat fragments containing a larger amount of the tree Daphniphyllum macropodum were occupied significantly more often than small, isolated fragments. The appearance of cabot's tragopan in the habitat fragments was best explained by the size of the fragments, the distance to the nearest suitable habitat and the amount of macropdous daphniphyllum trees. Our results could be used to improve the management of the forests where Cabot's tragopan occurs in southeastern China.     

Habitat structure and proximity to forest edge affect the abundance and distribution of forest-dependent birds in tropical coastal forests of southeastern Madagascar

Despite the fact that Madagascar is classified a biological `hotspot' due to having both high levels of species endemism and high forest loss, there has been no published research on how Madagascan bird species respond to the creation of a forest edge or to degradation of their habitat. In this study, we examined how forest bird communities and different foraging guilds were affected by patch habitat quality and landscape context (forest core, forest edge and matrix habitat) in the threatened littoral forests of coastal southeastern Madagascar. We quantified habitat use and community composition of birds by conducting 20 point counts in each landscape contextual element in October and November 2002. We found that littoral forest core habitats had significantly (p<0.01) more bird species than forest edge and matrix habitats. Thirty-one (68%) forest dependent species were found to be edge-sensitive. Forest edge sites had fewer species, and a higher representation of common species than forest interior sites. Twenty-nine species were found in the matrix habitat, and the majority of matrix-tolerant forest species had their greatest abundance within littoral forest edge habitats. Guild composition also changed with landscape context. Unlike other tropical studies with which we are familiar, we found that frugivorous species were edge-sensitive while sallying insectivores were edge-preferring. The majority of canopy insectivores (n=15, 88%), including all six endemic vanga species, were edge-sensitive. When habitat quality was assessed, the distributions of nine edge-sensitive species were significantly (p<0.01) affected by changes in habitat complexity and vegetation vertical structure in core or edge point counts. Therefore, we believe that changes in vegetation structure at the edge of littoral forest remnants may be a key indicator of mechanisms involved in edge sensitivity of forest dependent species in these forests. Our findings indicate that habitat fragmentation and degradation affect Madagascan bird communities and that these processes threaten many species. With continued deforestation and habitat degradation in Madagascar, we predict the further decline of many bird species.     

Population status of the Bornean orang-utan (Pongo pygmaeus) in the Sebangau peat swamp forest, Central Kalimantan, Indonesia

A survey of the density and population size of Bornean orang-utan (Pongo pygmaeus) was carried out in 1995 and 1996 in an area of peat swamp forest in the Sungai (River) Sebangau catchment, Central Kalimantan, Indonesia. Densities were calculated for four forest sub-types by counts of orang-utan sleeping platforms (nests) along line transects. Densities were found to be highest in the tall interior and mixed swamp forest sub-types. Low pole forest supported the lowest density. Habitat disturbance caused by logging was shown to affect orang-utan density within mixed swamp forest. The orang-utan population for a larger peat covered landscape unit (9200 km²), including the Sebangau catchment, was estimated to be between 5671 (±955) and 8951 (±1509) individuals, based upon the area of each forest type, the level of disturbance in each area and corrected to prevent overestimates. This study identifies the presence of a very large, self-sustaining orang-utan population in this region and emphasises the urgent requirement for greater protection of Kalimantan's peat swamp forests in the light of recent and rapid habitat degradation.     

Bryophyte species richness on boulders: relationship to area, habitat diversity and canopy tree species

Bryophytes growing on siliceous boulders (diameter 50-200 cm) were studied in two forests in east-central Sweden to investigate the influence of different canopy tree species on the bryophyte species richness. Granite boulders lying below crowns of Ulmus glabra (elm), Fraxinus excelsior (ash), Acer platanoides (maple), Quercus robur (oak), Betula pendula (birch), and Picea abies (Norway spruce) were studied in two mixed stands. Both boulder area and within-boulder habitat diversity were positively related to species richness. Boulders below the base-rich deciduous trees F. excelsior, U. glabra and A. platanoides held roughly twice as many species as those below P. abies, with Q. robur and B. pendula as intermediates. The rank order among trees was as expected from bark pH and litter decomposability in the literature. We also used sample plots to investigate species richness at a smaller scale. Within plots, intermediate levels of litter, inclination and exposed rock promoted species richness, and also the covering tree species had an effect. Individual plots were on average not more species-rich on large boulders than on small ones. This leads us to conclude that population extinctions on the plot-level, and re-colonisations from other parts of the boulder, are less important for species richness than within-boulder habitat diversity. Since species richness was lower under P. abies it is important to favour a diversity of tree species and to include base-rich deciduous trees in otherwise homogeneous Picea forests.     

Methods for conservation outside of formal reserve systems: The case of ants in the seasonally dry tropics of Veracruz, Mexico

Like most ecosystems of the world, tropical dry forests of the central coast of the Gulf of Mexico are inadequately preserved. Given that reserve expansion is unlikely, it is imperative that the conservation capacity of the matrix surrounding reserves is enhanced. Here, we examine the habitat value of isolated pasture trees and patches of secondary regrowth in terms of their terrestrial and arboreal ant assemblages in both a wet and dry season. These simplified wooded systems increase species densities within the agricultural matrix and provide habitat for some forest ant species. Estimated species richness of arboreal ants was particularly low on isolated trees, highlighting an important limitation. This was not the case for terrestrial ants, which were particularly species rich under isolated trees. We also found that the inter-site variations in species densities and similarity to the forest ant assemblage for terrestrial and arboreal strata were not correlated, suggesting that responses to restoration may not be as uniform as often thought. This has important implications for the use of indicator taxa in suggesting the response of other taxa. In terms of species composition, neither secondary regrowth nor isolated trees were appropriate replacements for forest fragments, even though the studied forest fragments were small (13-32 ha). The ant assemblages did not exhibit a seasonal change in composition. However, season influenced the contrast between habitats, with isolated trees being more distinct from pasture, and regrowth more closely resembling forests, during the wet season. Microclimatic variables indicate that the forests were least affected by the tropical dry season, and this may contribute to their characteristic fauna. We conclude that even small forest patches make a unique contribution to landscape conservation and that, where reserves are limited, conscientious management of the landscape matrix may provide some species with sufficient new habitat to survive outside of reserve systems. These conclusions are influenced by both season and strata studied.     

Scale-independent significance of river and riparian zones on three sympatric Myotis species in an agricultural landscape

Conserving biodiversity in agricultural landscapes is an urgent issue. The effective conservation of biodiversity requires plans based on species’ habitat preferences at multiple spatial scales. We examined how the foraging habitat selection of bats varied with grain size (50, 150, 250, and 350 m) and how habitat selection in the home range differed from that in the foraging habitat in an agricultural landscape. Focusing on three sympatric Myotis species (Myotis petax, Myotis gracilis, and Myotis frater), we radio-tracked 10 individuals of each species for 121 nights in Hokkaido, northern Japan. Rivers and broadleaved riparian forests were commonly preferred at multiple scales, although the preferred land-cover type was dependent on both extent and grain size for most species. The best grain sizes for predicting the foraging-habitat use of M. petax and M. gracilis were 50 and 150 m. By contrast, M. frater showed no tendency across the grain sizes. Our results indicate that it is necessary to consider both extent and grain size to understand the habitat selection of bats. Our findings also suggest that focusing primarily on preferred land-cover types at multiple scales is effective for conservation planning, given the limited resources in terms of time, manpower, and finances. Although arable did not negatively affect the selection of foraging habitats and home ranges in these bat species, preventing the loss of rivers and forests should be prioritized over preventing arable land expansion.     

Effects of habitat fragmentation on pollen flow and genetic diversity of the endangered tropical tree Swietenia humilis (Meliaceae)

Fragmentation of tropical forest represents a major threat to some tree populations by reducing local population size and gene flow from other populations. Both processes can decrease outcrossing rates and genetic variation in remnant stands. Despite these risks, some tree species have pollen vectors that mitigate these negative consequences for fragmented populations. In this paper, we assess both pollen flow and diversity of pollen sources in continuous forest and isolated stands of Swietenia humilis, a tropical tree species pollinated by small insects. Using seven nuclear microsatellite markers, we test the hypothesis that genetic diversity and the number of pollen donors are lower in remnant populations. Results show that allelic richness of seeds is lower in isolated populations (6.1 vs. 8.3 alleles per locus), even though adult populations do not show this difference.Pollen pool structure is greater in isolated patches (Φ_Iso = 0.26) than in continuous forest (Φ_For = 0.14), which yields estimates of the average effective number of pollen donors (N_ep) of 1.9 and 3.6 respectively. In addition, estimates of number of sires per mother indicate that isolated trees have half the number of pollen sources (4.98) than trees in the forest (9.8). Although extensive pollen movement (>2000 m) was recorded on both habitat conditions, indicating that fragmented patches are not isolated from pollen-mediated gene flow, this extensive pollen flow among trees in fragmented landscapes may not serve to counteract deleterious reproductive and genetic consequences of habitat fragmentation.     

A multi-taxa assessment of nestedness patterns across a multiple-use Amazonian forest landscape

Understanding how biodiversity is partitioned among alternative land-uses is an important first step for developing effective conservation plans in multiple-use landscapes. Here, we analysed nestedness patterns of species composition for nine different taxonomic groups [dung beetles, fruit-feeding butterflies, orchid bees, scavenger flies, leaf-litter amphibians, lizards, bats, birds and woody plants (trees and lianas)] in a multiple-use forestry landscape in the Brazilian Amazon containing primary, secondary and Eucalyptus plantation forests. A formal nestedness analysis was performed to investigate whether species-poor land-uses were comprised of a subset of species from more diverse forests, and the extent to which this pattern varied among taxa. At the landscape-scale the species-by-sites matrices were significantly nested for all nine taxonomic groups when both sites and species were sorted to maximally pack the species/occurrence matrix and, except for orchid bees when sorted by land-use intensity (primary forest to Eucalyptus plantation). Different patterns emerged when we conducted pairwise analyses of nestedness between the three forest types: (a) most of the taxonomic groups were nested in accordance with increased land-use intensity; (b) neither orchid bees nor leaf-litter amphibians from secondary forest made up a significant nested subset of primary forest species, although species found in Eucalyptus plantation sites were nested within secondary forest communities; and (c) lizards from Eucalyptus plantations were not a nested subset of either primary or secondary forest. Our findings emphasize the complex nature of patterns of species occupancy in tropical multiple-use forestry landscapes, and illustrate that there may be no easy solutions to questions regarding the conservation value of secondary and exotic plantation forests.     

Global population decline of the Great Slaty Woodpecker (Mulleripicus pulverulentus)

The Great Slaty Woodpecker (Mulleripicus pulverulentus) of South and Southeast Asia, the third largest woodpecker species in the world, is currently in the IUCN Red List category of Least Concern. This woodpecker appears associated with old-growth forests, and the rapid reductions in forest cover and old-growth area in Southeast Asia urged examination of its global population trends. We assessed population densities, tree diameter use by the woodpecker, and logging disturbance at 21 transects in four regions across the range of the species: west Borneo, Lingga Island (Riau Archipelago, Indonesia), Tenasserim (Myanmar), and west-central Myanmar. Transect survey effort was 937 km. We assessed rates of deforestation and loss of old-growth forest in the range of the species from expert review reports. By combining population density and forest cover data sets we calculated the global population trend of the species. We found a preference for large diameter trees by foraging and nesting Great Slaty Woodpeckers, and a reduction of the frequency of such trees in logged forests. Across the four study regions, between old-growth forests and logged forests, densities of Great Slaty Woodpeckers were reduced by 80-94%. Although Great Slaty Woodpeckers occur in 15 countries, ca. 70% of the global population occurs in just four countries (Myanmar, Indonesia, Cambodia, and Malaysia), three of which have high annual rates of deforestation and loss of old-growth forest. Our population calculations show that over the past century at least 90% of the global population of the Great Slaty Woodpecker has been lost. At present 26,000-550,000 individuals remain. The current global decline rate of ca. 59% ± SD 17% in three generations justifies IUCN Vulnerable or Endangered status. Contributing factors to the steep decline rate of the species are a long generation time of 5.9-8.2 years and an association with old-growth, lower elevation forests. The Great Slaty Woodpecker case adds an Asian example to a global pattern of specialized woodpeckers that are associated with old or natural forests.     

Population recovery of the threatened endemic Rodrigues fody (Foudia flavicans) (Aves, Ploceidae) following reforestation

In 1999, we intensively surveyed all suitable habitat on the Mascarene Island of Rodrigues and mapped 334 territories of the threatened endemic Rodrigues fody (Foudia flavicans). In addition, we recorded 58 unpaired males, 85 juveniles, and 100 grey-brown-plumaged birds, for a minimum estimated population size of 911 birds. This represents a near 100-fold increase in population size since 1968, which has been achieved in the absence of translocation or taxon-specific management. Birds were generally distributed in direct proportion to the availability of various forest types, but relatively more birds were found in mature, dense forests. Fody density at 10 selected sites, where vegetation surveys were carried out, increased significantly with increasing tree height, canopy cover and tree species diversity. This suggests that habitat management aimed at enhancing Rodrigues fody populations should focus on the protection of existing wooded valleys to allow forest maturation and expansion of afforested areas.     

Seeing the forest for the deer: Do reductions in deer-disturbance lead to forest recovery?

High levels of deer browsing can prevent canopy tree regeneration, but little is known about changes to forest size-structure following long-term deer herd reductions. We monitored changes in forest stand structure and composition in southwestern Ontario, Canada, over 28-years using permanent plots. Our study site was the largest remaining tract of Carolinian (deciduous) forest in Canada (11 km²), a habitat type that contains up to a fifth of Canada’s species at risk and is under intense anthropogenic pressures. We recorded declines in all tree size classes between 1981 and 1996, during which densities of white-tailed deer (Odocoileus virginianus) reached a peak of 55 deer km⁻². Despite significant and sustained deer herd reductions between 1996 and 2009, which reduced deer densities to 7 deer km⁻², there was limited recruitment of small trees and declines in basal area of tree species that were sensitive to deer browsing. Our results suggest that recovery from herbivory is a protracted process during which canopy tree regeneration may continue to decline despite a reduction in browsing pressure due to deer culling. Large declines in canopy-tree densities in Carolinian forests may lead to forest size-structures and herbaceous plant communities that resemble rare oak savanna habitat, creating difficult decisions for conservation managers aiming to protect rare and endangered species within native ecosystems. We recommend that managers protect Carolinian forest stands and encourage canopy tree regeneration by increasing seed sources of native trees. While deer control is essential in reducing forest damage, our results highlight the need to explore other forms of active management to expedite otherwise slow increases in tree density.