Black Woodpecker Research Articles

降雪期におけるクマゲラとオオアカゲラの採餌痕の比較と識別

2008年4月～2011年3月の降雪期に北海道空知地域で，クマゲラ Dryocopus martius とオオアカゲラ Dendrocopos leucotos の採餌場所を直接観察することにより，両種の採餌場所，つつかれ出た木くずや樹皮の大きさ，くちばし痕の幅を比較した．さらにこれらのデータを使って両種の採餌痕を識別する方法について検討した．また，博物館標本を用いてくちばしサイズの計測を行った．クマゲラのみ針葉樹で採餌し，採餌木の胸高直径はクマゲラの方が太かった．枯死木利用率は両種でほぼ同じあり，クマゲラだけ生幹で採餌し，オオアカゲラは枯枝で採餌することが多かった．つつかれ出た最も大きい木くずや剥がされた樹皮の大きさは，クマゲラの方が大きかった．くちばし痕の幅に影響を与える要因を調べるため一般化線形モデルで解析した結果，鳥種のみがくちばし痕の幅に影響を与え，鳥種×性，木くずの堅さ，樹種はくちばし痕の幅に影響を与えなかった．くちばし痕の幅はクマゲラで 4～7 mm，オオアカゲラで 2～5 mmと，6 mm以上のものはすべてクマゲラのものであった．1箇所でくちばし痕の幅を3つ測定できた場合の中央値は，クマゲラで 4～6 mm，オオアカゲラで 2～4 mmであり，5 mm以上はクマゲラだけであった．クマゲラのくちばし幅の実測データを使いブートストラップ法により確率を推定すると，最大値を用いるより，くちばし幅が3個測定できた場合で，その中央値が 5 mm以上である場合の確率の平均は0.904（95％パーセンタイル信頼区間：0.788～0.988）と高く，クマゲラの採餌痕を判別する基準としての信頼性は高かった．クマゲラとオオアカゲラの採餌痕を分類するために構築した樹形モデルでは，まずもっとも大きい木くずの大きさ13以上でクマゲラを分け，残ったデータを採餌位置で，生幹をクマゲラ，生枝，枯幹，枯枝をオオアカゲラと分類した．この場合のクマゲラの正答率は75.4％であった．標本を用いて，両種のくちばしを計測した結果，計測したどの部位に関しても明らかにクマゲラのくちばしは大きかった．

Breeding avifauna of the Special Protection Area Natura 2000 ‘Grądy Odrzańskie’ in Czernica and Siechnice counties, Wrocław district (Poland)

Abstract In 2009, in the Special Protection Area Natura 2000 ‘Grądy Odrzańskie’ in Czernica and Siechnice counties, Wrocław district, 95 breeding bird species were recorded. For 33 of them, maps of distribution of their breeding pairs are presented and for the remaining a relative abundance was estimated based on line transect method. In 2009, the following species were recorded in the study area for the first time: Cygnus olor, Crex crex, Upupa epops, and Picus canus. On the other hand, 11 species recorded in 1978-87 as breeding in the study area (Ciconia nigra, Pernis apivorus, Milvus migrans, Milvus milvus, Falco tinnunculus, Gallinago gallinago, Limosa limosa, Tringa totanus, Riparia riparia, Anthus campestris, Phoenicurus phoenicurus) were not recorded again in 2009. It has been shown that Saxicola torquata, Ficedula albicollis, Corvus corax and Remiz pendulinus have increased in numbers. The following species recorded in 2009 as breeding in the the study area: Cygnus olr, Ciconia ciconia, Circus aeruginosus, Crex crex, Alcedo atthis, Dryocopus martius, Picus canus, Dendrocopos medius, Lulula arborea, Sylvia nisoria, Ficedula albicollis, Lanius collurio and Emberiza hortulana are included in Annex 1 of the Bird Directive.

Black woodpecker Dryocopus martius (L., 1758) distribution, abundance, habitat use and breeding performance in a recently colonized region in SW Europe

Black woodpecker Dryocopus martius (L., 1758) distribution, abundance, habitat use and breeding performance in a recently colonized region in SW Europe

Modelling distribution of habitats required for different uses by the same species: Implications for conservation at the regional scale

Most modelling exercises use generic occurrence points of a species, but the distribution of habitats used for different purposes may differ. Modelling separately the availability of functionally different habitats may allow for the identification of the habitats mostly affecting/limiting distribution, with important implications for conservation. We analyzed the regional distribution of the black woodpecker in Northern Italy. We separately modelled the availability of feeding and nesting habitats at the fine scale (20m×20m), and compared the outputs with a more conventional distribution modelling procedure, which included all records and was developed at the territory scale (1km×1km). Both the conventional and feeding habitat models performed well (although they tended to under- and overestimate occurrence, respectively), whereas the nesting habitat model had a lower discriminatory ability. Nesting and feeding habitats show different relationships between woodpecker occurrence and habitat variables, this resulting in a weak overlap of the respective niches and in quite different distributions. The conventional model provided less information for management, being mainly affected by elevation and urbanized areas; the two specific models instead showed effects of habitat variables on occurrence of feeding and nesting sites. The availability of feeding habitat is likely the most important factor limiting distribution in the area and could be the focus of possible habitat management, which should include the preservation of grassland patches interspersed within woodlands, especially on South-facing, gently sloping mountainsides. Modelling separately the availability of functionally different habitats may provide useful information for conservation and management.

Black WoodpeckerDryocopus martiushabitat selection in the Italian Alps: implications for conservation in Natura 2000 network

SummaryThe Black WoodpeckerDryocopus martiusis the largest woodpecker of the Palearctic Region and it has been recognised as a keystone species whose presence provides critical resources to secondary cavity-users in European forest ecosystems. Here we investigate cavity tree and foraging-habitat selection of Black Woodpecker in three natural parks located in the central and eastern Italian Alps and included in the Natura 2000 network. A total of 94 cavity trees were identified, showing a minimum diameter of 35 cm and a mean diameter of 51 cm. We counted 30 active nests, but only 40% were newly excavated. Silver firAbies albaand larchLarix deciduawere preferred as cavity trees, with silver fir also associated with habitat surrounding the cavity trees. Norway sprucePicea abiesand Silver fir were found to be positively associated with the surroundings of feeding sites. Logistic regression models identified the average diameter at breast height and the average tree crown height as significant predictors, positively associated with both cavity trees (AUC: 0.988) and cavity tree plots (AUC: 0.866). Also, the total volume of dead logs and the percentage of understorey cover turned out to be significant predictors of feeding sites, showing a positive and a negative association, respectively (AUC: 0.708). Cross validation of logistic regression models indicated that only cavity tree models can be considered useful tools in conservation practice. Overall, our results indicated that the Black Woodpecker behaves like an opportunist when choosing feeding sites. On the other hand, our results also indicate that the Black Woodpecker clearly behaves as a demanding species when it selects cavity trees, showing a hierarchical pattern in habitat selection and a marked preference for large trees with high crown height. We discuss the implications of our results for the conservation of the Black Woodpecker in Natura 2000 alpine sites.

EDITOR'S CHOICE: Stepping stones are crucial for species' long‐distance dispersal and range expansion through habitat networks

Summary Climate and land‐use changes will require species to move large distances following shifts in their suitable habitats, which will frequently involve traversing intensively human‐modified landscapes. Practitioners will therefore need to evaluate and act to enhance the degree to which habitat patches scattered throughout the landscape may function as stepping stones facilitating dispersal among otherwise isolated habitat areas. We formulate a new generalized network model of habitat connectivity that accounts for the number of dispersing individuals and for long‐distance dispersal processes across generations. By doing so, we bridge the gap between complex dynamic population models, which are generally too data demanding and hence difficult to apply in practical wide‐scale decision‐making, and simpler static connectivity models that only consider the amount of habitat that can be reached by a single average disperser during its life span. We find that the loss of intermediate and sufficiently large stepping‐stone habitat patches can cause a sharp decline in the distance that can be traversed by species (critical spatial thresholds) that cannot be effectively compensated by other factors previously regarded as crucial for long‐distance dispersal (fat‐tailed dispersal kernels, source population size). We corroborate our findings by showing that our model largely outperforms previous connectivity models in explaining the large‐scale range expansion of a forest bird species, the Black Woodpecker Dryocopus martius, over a 20‐year period. The capacity of species to exploit the opportunities created by networks of stepping‐stone patches largely depends on species‐specific life‐history traits, suggesting that species assemblages traversing fragmented landscapes may be exposed to a spatial filtering process driving long‐term changes in community composition. Synthesis and applications. Previous static connectivity models seriously underestimate the importance of stepping‐stone patches in sustaining rare but crucial dispersal events. We provide a conceptually broader model that shows that stepping stones (i) must be of sufficient size to be of conservation value, (ii) are particularly crucial for the spread of species (either native or invasive) or genotypes over long distances and (iii) can effectively reduce the isolation of the largest habitat blocks in reserves, therefore largely contributing to species persistence across wide spatial and temporal scales.

Does fragmentation increase extinction thresholds? A European‐wide test with seven forest birds

AbstractAimTheory predicts that fragmentation aggravates habitat loss, increasing the extinction threshold of habitat specialists. However, contradictory empirical results have fuelled claims that fragmentation has been overemphasized, and more attention should be given to habitat loss for preserving species. We assess variation in species sensitivity to forest amount and fragmentation and evaluate if fragmentation is related to extinction thresholds in seven forest bird species.LocationEurope.MethodsWe use the percentage of forest cover and the proportion of cover occurring in the largest patch to partition effects of forest amount versus fragmentation, and apply logistic regression to model the presence–absence of 17 forest bird species. For seven species showing robust models, we define two fragmentation scenarios, low and maximum, across the forest cover gradient and quantify species' sensitivity to forest contraction with no fragmentation, and to fragmentation under constant forest cover. Finally, we develop two tests of the extinction threshold hypothesis by comparing the occurrence probability of each species under the two fragmentation scenarios at different forest covers.ResultsAs expected, forest contraction had negative impacts on the occurrence probability of all seven species modelled, but – in line with theory – fragmentation also led to a higher extinction threshold for three (Western capercaillie, Hazel grouse and Eurasian pygmy‐owl). One species (Black woodpecker) exhibited the opposite pattern indicating that it probably benefits from fragmentation. Differences among species responses may reflect dispersal abilities, specializations in resources/habitat characteristics and/or sensitivity to potential modifications of interspecific interactions.Main conclusionsAlthough forest amount is of primary importance for the persistence of forest specialist birds, fragmentation is also relevant for some, and neglecting forest fragmentation would be a mistake for these species. Species‐specific traits can be helpful for interpreting species' reactions to fragmentation, and it should not be assumed that it always, or never, matters.

Modelling distribution and potential overlap between Boreal Owl Aegolius funereus and Black Woodpecker Dryocopus martius: implications for management and monitoring plans

SummaryCorrelative species distribution models (SDMs) are increasingly widespread in the conservation literature. They can be used for a variety of purposes, including addressing practical conservation tasks on the basis of a spatially explicit assessment of environmental suitability for target taxa, which in turn allows for a transparent evaluation of needs and opportunities. Here we used the maximum entropy method (by means of the software MaxEnt) to model distribution of the rare Boreal Owl Aegolius funereus and the Black Woodpecker Dryocopus martius, which excavates the nest-holes used by the owl for breeding. We believe that monitoring surveys for Boreal Owl should consider areas suitable for both species as priority sites, whereas the provision of nest-boxes for the owl may be particularly desirable in habitat patches that are suitable for that species but not for the keystone species whose nest-holes represent the usual nest site for the owl. Finally, areas suitable for both species can represent priority areas for the conservation of forest birds in the Alps, as both species have been reported as umbrella and/or keystone species. Our example provides a possible framework to model management and monitoring opportunities in other species or species pairs, but such an approach can be used to infer the need for particular management options when both limiting factors and species distribution can be spatially modelled, and also to model the areas where different target species are more likely to overlap and interact. The use of distribution models as tools to address practical conservation tasks should also be encouraged in order to accomplish practical tasks according to sound knowledge and transparent methods.

北海道におけるクマゲラの繁殖期の分布

The Black Woodpecker Dryocopus martius was censused along one to three 2-km transects (a total of 1,036) situated in 920, 5-km quadrats (4.5 km×5 km), in Hokkaido from late April to late July, 1976–2012. Based on census results, records from the literature, and personal records of amateur ornithologists, Black Woodpeckers were recorded over almost all Hokkaido, except the plains. They occurred in 21.0% of quadrats in which censuses or observations were conducted. They were observed mainly in evergreen, mixed and deciduous broad-leaved forests, with occurrence rates (No. of transects of occurrence / No. of transects censused) of 11.8%, 16.6% and 6.2%, respectively, and at altitudes below 950 m.

L’ecologia del Picchio Nero, Dryocopus Martius, nelle foreste casentinesi come chiave per la possibile espansione della specie nell'Appennino

Ecological mathematical models are useful tools to define geographic distribution and ecological features of species, playing a fundamental role in defining conservation policies. Through the various methods we can use, recently, those which work with only-presence-data are growing in popularity and particularly MaxEnt. The recent colonization of Foreste Casentinesi National Park by Black Woodpecker represent a very interesting study-case to show how this method work, analysing possible evolution of an expansion process that is still evolving.

가야산국립공원 까막딱다구리의 번식 현황

This study was conducted from April 2012 to June 2012 to analyze breeding status of Black woodpeckers (Dryocopus martius) in the Gayasan National Park. Nest height, tree diameter which a nest built and altitude at the nest site of Black woodpeckers were 17.4 m, 63.8 cm and 587 m, respectively. A pair of Black woodpeckers completed a clutch in 4 eggs on 7 May and 3 of eggs hatched on 24 May 2012. Both female and male incubated eggs and never left eggs without one of parents. A male more contributed to build a nest than a female. Incubation duration was higher in a male than in a female. Nestlings made a begging call in a nest during the growing period. Begging frequency of nestlings increased from 11 days up to 20 days after hatching. After then, nestlings reduced begging and fledged a nest 24 days after hatching. This study provided information of breeding ecology to protect and manage population of Black woodpeckers which are endangered species in South Korea.

Assessing the role of landscape connectivity in recent woodpecker range expansion in Mediterranean Europe: forest management implications

Woodpecker species have significantly expanded their ranges in the last decades of the twentieth century in Mediterranean Europe, which seems to be closely related to forest maturation following large-scale decline in traditional uses. Here we assess the explicit role of forest landscape connectivity in the colonization of the Great Spotted Woodpecker (Dendrocopos major) and the Black Woodpecker (Dryocopus martius) in Catalonia (NE Spain). For this purpose we combined data on breeding bird atlas (10 × 10 km; 1980–2000) and forest inventories (c. 1 × 1 km, 2000). Forest connectivity was measured through graph theory and habitat availability metrics (inter- and intra-patch connectivity) according to species median natal dispersal distances. The best regressions from a set of alternative models were selected based on AICc. Results showed that connectivity between areas of mature forests [diameter at breast height (dbh) ≥ 35 cm] affected Black Woodpecker colonization events. The probability of colonization of the Great Spotted Woodpecker was greater at localities near the sources of colonization in 1980 and with a high connectivity with other less developed forest patches (dbh < 35 cm). The spatial grain at which landscape connectivity was measured influenced the model performance according to the species dispersal abilities, with the species with the lower mobility (D. major) responding better to the forest connectivity patterns at finer spatial scales. Overall, it seems that both species could expand further in European Mediterranean forests in upcoming years but at slower rates if landscape connectivity according to species requirements does not continue to increase. Hence, a proactive and adaptive management should be carried out in order to preserve these species while considering the related major impacts of global change in Mediterranean Europe.

Heart rot as a key factor for cavity tree selection in the black woodpecker

Cavity nesting birds invest considerable time and effort into the construction of nests. The investment can be particularly high for species such as the black woodpecker (Dryocopus martius) that selects living trees as nest substrates. However, the investment may be reduced if fungal rot is present to help soften the wood. We used Resistograph drills to objectively assess fungal decay and tested whether black woodpeckers preferred trees with heart rot as sites for cavity starts. In doing so we also examined the distribution of fungal decay across the tree radius, analysed location of cavity starts with respect to proximity to heart rot, and evaluated wood condition at fresh and old cavity starts. Heart rot was significantly more common in beeches (Fagus sylvatica) with cavity starts than in random reference beeches. Fungal decay was not evenly distributed across the tree radius, but was more prevalent both in the central and outer thirds than in the middle third. Distance to heart rot was smaller from cavity starts than from random drills, suggesting a preference to initiate cavities close to heart rot. Wood density at fresh cavity starts was significantly higher than at old cavity starts. Collectively, these findings imply that black woodpeckers prefer to excavate cavity starts in beeches with heart rot, which the woodpeckers can detect based on cues unavailable to humans. The decay is reducing the energy expenditure of the black woodpecker and is a part of the long time excavation strategy. The cavity starts are an important factor in the process of excavating the large black woodpecker cavities in beech that enhance biodiversity in managed forests. Future studies should attempt to uncover the mechanisms woodpeckers use in selecting the locations of cavity starts.

Habitat requirements of the Black Woodpecker, Dryocopus martius, in Hyrcanian forests, Iran

The relationships between the Black Woodpecker (Dryocopus martius (Linnaeus, 1758)) abundance and forest characteristics and the role of coarse woody debris for habitat selection were assessed. One hundred point counts were conducted 250 m apart in Hyrcanian forest in northern Iran from 21 April to 21 May 2009. There was a noticeable difference in forest structure between areas where the Black Woodpecker was present and absent, with the species preferring the later stages of forest succession. Tall and large diameter trees, high volumes of coarse woody debris, especially large snags, and dense canopy cover, all of which characterise mature forests, are significantly higher in areas where the Black Woodpecker occurs. Altogether, the conservation of the Black Woodpecker depends to a large extent on how the forests they inhabit are managed.

Nest-Sites used by Stock DovesColumba oenas: What Determines their Occupancy?

Nest-site preferences of the Stock Dove Columba oenas population breeding in holes excavated by the Black Woodpecker Drycopus martius in three sites in western Poland was examined. During the surveys, 176 different trees with 326 holes of Black Woodpeckers were found and investigated. Habitat data at nest locations were characterized on a fine microhabitat scale — hole tree. We used individual selection indices and canonical variate analysis to describe nest-site preferences. Both analyses provided similar results. Nest-site selection of the Stock Dove was consistently associated with live beeches Fagus sylvatica with more than one hole. These features were clearly associated with diameter at breast height. Moreover, holes situated higher in tree trunk were preferred. Dead trees, mostly Scots Pines Pinus sylvestris, were avoided by the Stock Dove. We suggest that positive selection for smooth-barked beech trees with a number of holes, as well as holes situated higher might reduce the risk of predation by arboreal predators, e.g. the Pine Marten Martes martes. The positive selection for live trees, and clear avoidance of the dead ones, may reduce the cost of incubation and thermoregulation. Moreover, the live beech trees have long life expectancy compared to other tree species. Our results provide evidence that large alive beech trees with the number of holes excavated by Black Woodpeckers are necessary for maintaining breeding population of the Stock Dove.

“Lifespan” of woodpecker-made holes in a primeval temperate forest: A thirty year study

Woodpeckers, able to excavate holes in trees, can provide resources critical for non-excavator hole users. Supply of woodpecker-made holes in forests depends on excavation rates by the birds and holes’ persistence times. I use 30 years of data from a primeval forest (strictly protected reserve, Białowieża National Park, E Poland) to determine how long woodpecker-made holes persist, and whether their persistence varies across forest types, tree species and conditions, and woodpecker species. I followed the fate of 719 breeding holes, excavated by eight woodpecker species, for up to 27 years, from 1979 to 2010. Almost 80% of hole losses were caused by collapse of either the tree or the section supporting the hole. Holes were retained for (median) 6–7 years in riverine and oak-hornbeam forest but 10 years in coniferous forest. These differences can be explained by almost completely non-overlapping sets of tree species used in these different habitats. Lifespan of holes varied by tree species, ranging from four ( Picea abies) to >22 years ( Pinus sylvestris, almost 100% dead). The long lifespan of holes in the dead Pinus was exceptional, as otherwise, persistence was much lower for holes excavated in dead trees or limbs (5 years) than for those in living substrates (9 years). Tree species with higher frequency of holes in dead wood showed lower persistence times of holes. Lifespans of holes excavated by individual woodpecker species varied widely and was strongly dependent on frequency with which the species excavated in dead wood. Holes of Dendrocopos minor and Dendrocopos leucotos (only in dead wood) persisted for four years, while holes of Dendrocopos major (able to excavate in living sapwood of some trees) lasted for nine, and those of Dryocopus martius for 18 years. Retention of dead P. sylvestris, decaying Quercus robur in stands and addition/retention of aspens ( Populus tremula and Populus tremuloides) in them would provide conditions to increase the availability of relatively persistent woodpecker holes in forests of the Northern hemisphere.

Steigende Bestandszahlen bei Spechten und anderen Vogelarten dank Zunahme von Totholz? | An increase in the population of woodpeckers and other bird species thanks to an increase in the quantities of deadwood?

Results from the monitoring programs of the Swiss Ornithological Institute show that the breeding populations of several forest species for which deadwood is an important habitat element (black woodpecker, great spotted woodpecker, middle spotted woodpecker, lesser spotted woodpecker, green woodpecker, three-toed woodpecker as well as crested tit, willow tit and Eurasian tree creeper) have increased in the period 1990 to 2008, although not to the same extent in all species. At the same time the white-backed woodpecker extended its range in eastern Switzerland. The Swiss National Forest Inventory shows an increase in the amount of deadwood in forests for the same period. For all the mentioned species, with the exception of green and middle spotted woodpecker, the growing availability of deadwood is likely to be the most important factor explaining this population increase.

Nest and roost tree characteristics of the Black Woodpecker Dryocopus martius in northern Honshu, Japan

Nest and roost tree characteristics of the Black Woodpecker <i>Dryocopus martius</i> in northern Honshu, Japan

Nest site environment of the Black Woodpecker Dryocopus martius in northern Honshu, Japan

Nest site environment of the Black Woodpecker Dryocopus martius in northern Honshu, Japan

Habitat use, Home Ranges and Census Techniques in the Black WoodpeckerDryocopus martiusin the Alps

We focused upon habitat use and home range size variation in an alpine population of the Black Woodpecker Dryocopus martius. Habitat selection analyses showed that the dominant local forest type, i.e. Mountain Pine Pinus mugo uncinata, was significantly avoided. Scots Pine Pinus sylvestris stands were positively selected, likely because of the abundance of ants; Beech Fagus sylvatica was chosen for nesting and roosting. A high level of flexibility in ranging behaviour and habitat selection, with remarkable among- and within-individual variability, was recorded. We assessed the reliability of census techniques by comparing results obtained by radio-telemetry and territory mapping, which showed that territory mapping failed to identify all pairs detected through radio-tracking. Several behavioural and ecological traits may bias count results irrespective of the methods used. Mapping methods are particularly ineffective because the Black Woodpecker is weakly territorial: in our study area home range overlap was rather high and no territorial defence was detected. Based on these results, the potential of the Black Woodpecker as ecological indicator is questioned.