Ann. Zool. Fennici 43: 86–95 ISSN 0003-455X Helsinki 28 April 2006 © Finnish Zoological and Botanical Publishing Board 2006

Woodpeckers: distribution, conservation, and research in a global perspective

Grzegorz Mikusiński

Grimsö Wildlife Research Station, Department of Conservation Biology, Swedish University of Agricultural Sciences, SE-730 91 Riddarhyttan, Sweden (e-mail: [email protected])

Received 7 Oct. 2005, revised version received 6 Mar. 2006, accepted 6 Feb. 2006

Mikusiński, G. 2006: : distribution, conservation, and research in a global perspec- tive. — Ann. Zool. Fennici 43: 86–95.

The main aim of this paper is to examine and discuss the global pattern of diversity from a conservation perspective. In addition, I review ecological traits and the conservation status of the entire family Picidae, and relate these factors to the human driven change in their . Finally, I present a global overview of the research on woodpeckers in order to identify the major gaps in our knowledge which render the management of populations of these difficult. The hotspots of woodpecker spe- cies richness identified by GIS were found in tropical and subtropical forests of South- East Asia, South and Central America, and equatorial Africa. Most of these hotspots were located in developing countries. However, almost 90% of articles published in 1985–2004 encompassed studies performed in North America and Europe, that is, in geographic areas harbouring only 17% of the global number of Picidae species.

Introduction their drilling for phloem sap and thus their activ- ities can influence entire community structures The family Picidae, which encompasses wood- (Blendinger 1999, Schlatter & Vergara 2005). peckers, wrynecks, and contains ca. 216 Through wood excavation activities, including closely related species, all with strong ties to nest construction and foraging, woodpeckers forest environments. Trees, snags and logs are play a role in wood decomposition processes primary substrates providing nesting sites, shel- (Farris et al. 2004). It has also been suggested ter, and food for the majority of woodpeckers that woodpeckers function as dispersal vectors (Winkler et al. 1995). One striking feature of for wood-living fungi (Jackson & Jackson 2004). woodpeckers is their ability to excavate cavi- It is quite apparent from these relationships that ties in living and dead trees (Winkler & Christie this avian family plays a significant ecological 2002). Due to this “engineering activity”, wood- role in forest environments and communities. peckers have been proposed as key-stone spe- Woodpeckers occur in all types of forest cies in several communities with large numbers and woodland and are found on all continents of secondary cavity nesters (Daily et al. 1993, except of Australia and Antarctica (Winkler et Jones et al. 1995, Conner et al. 2004, Martin al. 2005). Woodpeckers are virtually absent from et al. 2004, Ojeda 2004). Moreover, facultative treeless landscapes such as desert, tundra and sap-consuming species are also benefited by alpine areas. In addition, most isolated islands ANN. ZOOL. FENNICI Vol. 43 • Woodpeckers: distribution, conservation and research 87 lack woodpeckers. Most woodpeckers are sed- other threatened organisms — is loss. entary and are generally considered to be Logging of vast areas of woodland as well as relatively poor dispersers (e.g. Higuchi & Koike their conversion to farmland has been the major 1978). Blackburn et al. (1998) conducted a global cause of range contractions, regional extinctions, analysis and found that body mass of woodpeck- and population declines both now and histori- ers was rather weakly correlated with the size of cally (Winkler & Christie 2002). Dependence of their geographic ranges. Blackburn et al. (1998) woodpeckers on certain forest characteristics found that woodpecker geographic range sizes typical for unmanaged forest (i.e. presence of decreased with increased woodpecker species large and old trees, high structural diversity, richness and that species living in high latitudes and presence of large quantities of dead wood) tended to be more widely distributed. Interest- makes them particularly susceptible to forestry ingly, the best predictor of species richness for practices. Short-rotation schemes, selection of woodpeckers was the area of a given geographic few most productive tree species, even-age struc- region; smaller regions had more woodpecker ture, removal of dead wood, active fire suppres- species and more endemics. sion, and replacement of native tree species with Several species of woodpeckers have expe- fast-growing exotics apparently degrade habi- rienced dramatic population declines and range tat for woodpeckers (Angelstam & Mikusiński contractions due to habitat loss and degradation 1994). Alternatively, in areas with traditional, through various human activities (Winkler & low-intensity agricultural practices as is the case Christie 2002). This applies to large, area-sen- in several regions of Europe, woodpeckers may sitive species such as the ivory-billed wood- be relatively abundant in sparsely forested land- pecker ( principalis) or imperial scapes that contain elements of forest structure woodpecker (C. imperialis) that depend upon such as large, older trees (Mikusiński & Angel- vast areas of unmanaged forest as well as small stam 1997, 1998). In these areas, the clearance but highly specialised species such as the red- and intensified use of such semi-open landscapes cockaded woodpecker (Picoides borealis) or poses the main threat for woodpecker species South American piculets with small geographic (Tucker & Evans 1997). ranges. The effects of human activities on wood- The strong association that woodpeckers dis- pecker assemblages have been observed at dif- play with forest environments and their sensi- ferent scales. In a country-by-country analy- tivity to structural and compositional changes sis, Mikusiński and Angelstam (1997, 1998), in their habitats caused by human action has reported negative population trends for most been a reason for utilizing woodpeckers in forest European woodpeckers and related species rich- and landscape management (e.g. Angelstam & ness to the degree of anthropogenic change for Mikusiński 1994, Diaz 1997, Hutto 1988, Jans- this group of species. In a study from north-east- son 1998, Nilsson et al. 2001, Hess & King 2002, ern Poland, species richness for woodpeckers Lammertink 2004, Uliczka et al. 2004). Wood- was positively correlated with the availability of peckers may fit different concepts that recom- dead wood and large deciduous trees (Angelstam mend use of surrogate species in practical con- et al. 2002) — factors which are closely associ- servation. Woodpeckers have been suggested as ated with the level of naturalness of forest stands. indicators for forest biodiversity (Mikusiński & Strong negative correlation between woodpecker Angelstam 1998, Nilsson et al. 2001). It has been biomass and density with logging intensity has argued that since several woodpecker species been found on Borneo (Lammertink 2004) and display a highly specialised selection of resources the Malaysian peninsula (Styring & Ickes 2001). that are typical of naturally dynamic forests (e.g. Conner et al. (1975) reported higher diversity of dead wood, big and old trees) that their pres- woodpecker species in uncut versus cut wood- ence may indicate high overall biodiversity. The lands in Virginia. empirical evidence supporting this hypothesis is Human impact on woodpecker populations growing. Mikusiński et al. (2001) demonstrated encompasses several factors. The most obvi- a strong positive relationship between the number ous factor for woodpeckers — as well as many of woodpecker species and overall forest 88 Mikusiński • ANN. ZOOL. FENNICI Vol. 43 species richness at the landscape scale in Poland. conservation perspective. I also review some The lesser spotted woodpecker ( ecological traits and the conservation status of minor) has been found to be a reliable indicator of the entire family Picidae and relate them to the the occurrence of avian deciduous forest special- human driven change in their habitats. Finally, ists in northern Europe (Jansson 1998, Roberge & I present a global overview of the research on Angelstam 2006). Also tree species diversity was woodpeckers in order to identify the major gaps found to be positively correlated with the number in our knowledge. of woodpecker species observed in one study performed in south-central Sweden (Angelstam 1990). Martikainen et al. (1998) found high num- Material and methods bers of threatened wood-species in areas with white-backed woodpeckers (Dendrocopos Analyses in this study were performed at the leucotos) in Finland and Russian Karelia. global scale. I created a spatially-explicit Geo- Woodpeckers have also been proposed as graphic Information System (GIS) database on indicators of structural diversity and ecological the distribution of the breeding ranges of 216 quality of forest habitats and as umbrella/focal Picidae species, including woodpeckers, wry- species for forest and landscape management necks and piculets. The source of information on (McClelland & McClelland 1999, Derleth et al. geographic ranges of species was taken from dis- 2000, Angelstam et al. 2002, Pakkala et al. 2002, tribution maps published in Winkler and Christie Lammertink 2004). Hess and King (2002) used (2002). Spatial analyses were performed using the pileated woodpecker ( pileatus) ArcView 3.2 (ESRI 2000). A set of global maps as focal species of mature forest for conserva- provided with this software was used as back- tion planning in North Carolina. Two species ground information during the process of digi- of woodpeckers have been employed as focal talisation. In addition, information on the global species in designing a forest habitat network distribution of major vegetation zones was pro- in northern Italy (Bani et al. 2002). The habi- vided with this software. The spatial resolution tat requirements of the three-toed woodpecker of the created database corresponded to a grid (Picoides tridactylus) have been used to propose with cell dimensions 1° latitude ¥ 1° longitude. the quantitative snag targets for the conifer- Breeding ranges of all species were manually ous forest management in Europe (Bütler et digitised into this grid and then summarised spa- al. 2004). In the state of Mississippi, the suc- tially using the overlay function in vector format. cessful restoration of pine-grassland habitat for Borders between adjacent cells with the same red-cockaded woodpeckers resulted in increased number of woodpecker species were then dis- diversity of bird community (Wood et al. 2004). solved. This resulted in a vector-based map with Moreover, woodpeckers have been used to pre- polygons with values corresponding to 1–25 spe- dict the impact of forest management on wild- cies present. life habitats (Cox & Engstrom 2001, Marzluff Information on woodpeckers listed into dif- 2002). Angelstam et al. (2004) proposed several ferent threat categories according to IUCN clas- woodpeckers as focal species for the assessment sification as well as on the numbers of wood- of forest habitat networks in Europe applying pecker species present in different countries was habitat suitability modelling. In summary, wood- extracted from BirdLife International homepage peckers are an important systematic group from in the Search for Species mode (www.birdlife. forest and landscape management perspectives org/datazone/species/index.html). The data on because of their sensitivity to forestry and other woodpecker’s body size and their diet was assem- anthropogenic impacts on the forest environ- bled from Winkler and Christie (2002). ment. It remains to be seen whether they will be The literature survey for articles on wood- used to their full capacity as tools in forest biodi- peckers has been performed using Wildlife and versity management in a global perspective. Ecology Studies Worldwide database (NISC In this paper I examine and discuss the 2005). I searched for articles that contained global pattern of woodpecker diversity from a at least one of following words in the title ANN. ZOOL. FENNICI Vol. 43 • Woodpeckers: distribution, conservation and research 89

Fig. 1. Global pattern of species richness in family Picidae.

12 50

10 45

8 40 35 6 30 4 25

Mean number of species 2 20 0 Number of species 15

(571) 10 Temperate Temperate

scrub (151) 5 taigas(2345) forests (524) Boreal forest/ forests (1440) dry broad-leaf Mediterranean broad-leaf and savannas, and moist broad-leaf

shrublands (887) 0 Deserts and xeric coniferous forests shrublands (1065) Tropical and subtr. Tropical and subtr. Tropical and subtr. 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 mixed forests (1319) grasslands, savannas, and shrublands (1386) Gross Domestic Product in 2003 (USD) Temperate grasslands, Fig. 2. Mean number of woodpecker species in major Fig. 3. Number of woodpecker species in countries with woody vegetation types. Number of 1 ¥ 1 geographic different Gross National Product per capita according degree plots representing each type in parentheses. to UNEP (2005). Only countries with area > 5000 km2 Bars denote 95% confidence intervals of the mean. were included (n = 135).

(translated title): woodpecker(s), wryneck(s), the regions of southeast Asia and northern and (s), flicker(s), sapsucker(s), flameback(s), central parts of South America as species rich- goldenback(s), yellownape(s). I covered a 20- ness hotspots with at least 15 species present at year period (1985–2004). All titles and abstracts the regional level (Fig. 1). In particular, hotspots (when available) were reviewed and the follow- were found in Myanmar, Thailand, Vietnam, ing parameters were recorded in spread sheet Cambodia, Malaysia and Indonesia in Asia, as format: species, year of publication, country, well as in , Colombia, Peru, Ecuador and continent, first author and type of study (ecologi- Suriname in South America. Equatorial Africa cal, behavioural, faunistic and biogeographic, and Central America also had relatively high other). Publications concerning two or more spe- global levels of woodpecker species richness. cies of woodpeckers were recorded as “several Among different major vegetation zones with species” instead of species names. All references woody vegetation, moist broadleaved tropical that appeared two or more times in the database and subtropical forests had, on average, the high- were manually removed. est number of woodpecker species (Fig. 2). Most occurrences of high woodpecker species rich- ness were found to be in economically develop- Results ing countries (Fig. 3). Ants, other arthropods, fruits and berries The map illustrating the global pattern in spe- were among the most commonly observed food cies richness within family Picidae pointed to items taken by woodpeckers (Winkler & Chris- 90 Mikusiński • ANN. ZOOL. FENNICI Vol. 43

80 IUCN as threatened or near threatened in the 70 following categories: CR = 3 species, VU = 60 7 species, NT = 15 species (Table 1). Almost 50 half of them (12 species) are considered as 40 restricted-range species (i.e. with geographic 2 30 range < 50 000 km ). Most of the endangered species occur in areas with generally high wood- 20

Woodpecker species (%) pecker species richness. The percentage of spe- 10 cies in different size classes in threatened (near 0 s s r threatened) species and non-threatened catego- Ants Sap Othe ries is illustrated in Fig. 5. The proportions of Termites Vertebrates Seeds & nuts threatened (near threatened) species in differ- Fruits & berries Other arthropod ent size classes were dissimilar from those of Woodboring the remaining woodpecker species ( χ2 = 11.4, Fig. 4. Diet of Picidae according to species accounts in df = 5, p = 0.044). In particular size class 10– Winkler and Christie (2002). 15 cm (containing mostly piculets) and the larg- est woodpeckers were relatively more abundant tie 2002; Fig. 4). Clearly, well-described and among threatened (near threatened) species in known species had much higher numbers of comparison with the remaining species. Habitat foods listed. Interestingly, this source indicates loss and degradation due to forest logging and that the diets of 37 species (17%) are virtually removal of wood are the major threats indicated unknown to science. for all listed species. In some cases, hunting In total, 25 species of Picidae are listed by and collecting (e.g. ), forest

Table 1. Species listed by IUNC as threatened or near threatened. Categories: Critically Endangered (CR), Vulner- able (V), Near Threatened (NT). Regions: Africa (AF), Asia (AS), Latin America (LA), North America (NA).

Species Category Region Comments

Rusty-necked piculet ( fuscus) NT LA restricted-range species Speckle-chested piculet (Picumnus steindachneri ) VU LA restricted-range species Tawny piculet (Picumnus fulvescens) NT LA restricted-range species Ochraceous piculet (Picumnus limae) VU LA restricted-range species Mottled piculet (Picumnus nebulosus) NT LA Guadeloupe woodpecker ( herminieri ) NT LA restricted-range species Red-headed woodpecker (Melanerpes erythrocephalus) NT NA Knysna woodpecker ( notata) NT AF restricted-range species Stierling’s woodpecker ( stierlingi ) NT AF Sulu woodpecker (Dendrocopos ramsayi ) VU AS restricted-range species Arabian woodpecker (Dendrocopos dorae) VU AS Red-cockaded woodpecker (Picoides borealis) VU NA Chocó woodpecker (Veniliornis chocoensis) NT LA restricted-range species Yellow-browed woodpecker (Piculus aurulentus) NT LA Fernandina’s flicker (Colaptes fernandinae) VU LA restricted-range species Helmeted woodpecker (Dryocopus galeatus) VU LA restricted-range species Black-bodied woodpecker (Dryocopus schulzi ) NT LA Andaman woodpecker (Dryocopus hodgei ) NT AS restricted-range species Guayaquil woodpecker (Campephilus gayaquilensis) NT LA Imperial woodpecker (Campephilus imperialis) CR LA probably extinct Ivory-billed woodpecker (Campephilus principalis) CR NA < 50 individuals Red-collared woodpecker (Picus rabieri ) NT AS Olive-backed woodpecker (Dinopium rafflesii ) NT AS Okinawa woodpecker (Sapheopipo noguchii ) CR AS restricted-range species Buff-necked woodpecker (Meiglyptes tukki ) NT AS ANN. ZOOL. FENNICI Vol. 43 • Woodpeckers: distribution, conservation and research 91

30 800 Not threatened (%) Woodpecker species Threatened (%) Publications (1985–2004) 25 700

600 20 500 15 400

10 Number 300 Woodpecker species (%)

5 200

0 100 < 10 10–15 15–20 20–25 25–30 30–35 > 35 Body length (cm) 0 North Latin Europe Asia Africa Fig. 5. Body length in globally threatened (near threat- America America ened) vs. unthreatened species of woodpeckers. Fig. 6. Number of articles found in Wildlife & Ecology Studies Worldwide database (NISC 2005) and number of woodpeckers in different regions of the world. fires and hurricanes (e.g. red-cockaded wood- pecker) were considered to be additional causes Table 2. Species with highest number of articles pub- of population declines. lished between 1985 and 2004 according to Wildlife & In total, 1252 articles on woodpeckers pub- Ecology Studies Worldwide database. lished between 1985 and 2004 were found in Species Number of articles Wildlife and Ecology Studies Worldwide data- base. These included 1050 single-species articles Red-cockaded woodpecker that encompassed 65 species. Table 2 provides (Picoides borealis) 301 the list of the 15 species with highest numbers of Great spotted woodpecker articles published. I found a great disproportion (Dendrocopos major) 62 Northern flicker in the number of woodpecker species occurring (Colaptes auratus) 61 in Europe and North America and the number of Pileated woodpecker articles published about these species (Fig. 6). (Dryocopus pileatus) 58 (Dryocopus martius) 55 Discussion Acorn woodpecker (Melanerpes formicivorus) 54 Middle spotted woodpecker The global pattern of species diversity in - (Dendrocopos medius) 40 dae generally follows the well-known latitudinal White-backed woodpecker gradient of decreasing species richness from (Dendrocopos leucotos) 36 Red-bellied woodpecker lower to higher latitudes (Rosenzweig 1995, (Melanerpes carolinus) 27 Gaston 2000). This trend confirms an earlier Three-toed woodpecker finding at a much more coarse resolution by (Picoides tridactylus) 24 Blackburn et al. (1998). Identified hotspots of Red-headed woodpecker woodpecker diversity largely overlapped with (Melanerpes erythrocephalus) 23 Yellow-bellied Sapsucker distribution of hotspots of avian species richness (Sphyrapicus varius) 22 (Orme et al. 2005). In the case of woodpeck- Wryneck ers, the prerequisite for high species richness (Jynx torquilla) 21 appears to be presence of vast areas of woodland Downy woodpecker with high structural and compositional diversity. (Picoides pubescens) 20 Lewis’s woodpecker These environments are found mostly in tropi- (Melanerpes lewis) 16 cal and subtropical moist broadleaved forests of 92 Mikusiński • ANN. ZOOL. FENNICI Vol. 43 south-east Asia and South America (Figs. 1 and the fastest is occurring. In 2). Temperate and boreal forest vegetation zones addition, many parrot species are small island have a moderate number of species present at endemics. regional level. Does the relatively low proportion of offi- In a global perspective, arthropods clearly cially listed species mean that woodpeckers as dominate diets in Picidae (Fig. 4). However, a group of forest specialists are not particularly woodpecker diets also include vegetable items threatened by recent global intensification of log- such as fruit, nuts, berries and sap. I found a ging and other human-related changes affecting relatively low proportion of species that spe- forest environments? A closer look at the geo- cialised in wood-boring beetles and their larvae graphic locations of the hotspots of woodpecker (< 30% of species), the food often perceived species richness may suggest the opposite. Most as most typical for woodpeckers. Interest- hotspots are located in areas with tropical and ingly, ants seem to be an important ingredient subtropical moist forests as the major vegeta- of woodpecker diets world-wide. An obvious tion types. Since the majority of these areas weakness of this analysis is that the data used have been recently subjected to intensive clear- are not quantitative and thus it is difficult to ing operations the amount and quality of avail- know the importance of different food items able woodpecker habitat has declined drastically. for lesser-known species. Detailed studies on Estimated cumulative forest loss in Malaysia, food of European woodpecker species indicate Myanmar, Thailand and Vietnam, countries that significant regional and seasonal variations in harbour the majority of Asian woodpecker diver- diets (Cramp 1985). Information on the diet sity hotspots, amount to 39%, 55%, 71% and of the great majority of woodpecker species 68%, respectively (FAO 2000, Pahari & Murai comes not from comprehensive foraging stud- 1999). These figures illustrate loss of original ies or stomach contents analyses but from more forest cover but are silent on the structural and or less incidental observations. Askins (1983) compositional changes in managed forests that compared foraging behaviour of 11 species of negatively affect the quality of woodpecker habi- woodpeckers in Guatemala, Maryland, and Min- tats (e.g. Lammertink 2004). nesota and found a similar degree of specialisa- Similarly, forest loss in the South American tion in both tropical and temperate species. I hotspots is drastic. In the case of Brasilian Ama- argue that with more knowledge on foraging zonia, the tropical forest area remained a largely habits of woodpeckers we are going to see, not intact area until the inauguration of the Transa- only a broader spectrum of different food items mazon Highway in 1970, but the pace of forest utilised by particular species, but also a clearer clearing has been rapid since then (Fearnside pattern of seasonal and regional specialisation 2005). Also, in Colombia, Peru, and Ecuador the and the importance of versus vegetarian deforestation has been a major land-use change ingredients in diets. affecting entire regions (Pahari & Murai 1999). Judging from the proportion of woodpecker In an area of over 3000 km2 located at the border species listed by IUCN (11.5%), the global con- between Colombia and Ecuador — within one servation status of this group of birds is not of the woodpecker diversity hotspots — Viña extreme. Some other broadly distributed groups et al. (2004) estimated with the use of satellite of forest birds like parrots (Psittacidae), horn- images the deforestation rate during a 23-yr bills (Bucerotidae), or nuthatches (Sittidae) have period at 43% and 22% on the Colombian and higher proportions of threatened species (40%, Ecuadorian sides of the border, respectively. 39% and 27%, respectively), while others like The establishment of protected areas (PA) in tits (Paridae) or wrens (Troglodytidae) have woodpecker diversity hotspots is not necessarily lower proportions of threatened species (5.5% securing the maintenance of their natural habi- and 9.2%, respectively). High proportions of tats. In protected areas in south-western Borneo threatened species among parrots and hornbills (Kalimantan) for example, the lowland forest may be partly explained by the fact that these cover declined by 56% (29 000 km2) from 1985 families are nearly exclusive to the tropics where to 2001 (Curran et al. 2004). ANN. ZOOL. FENNICI Vol. 43 • Woodpeckers: distribution, conservation and research 93

I predict that a clear positive relationship in temperate versus tropical zones. Fifteen North between the deforestation rate and human popu- American and European species of woodpeck- lation density (Pahari & Murai 1999), consid- ers (7% of Picidae) accounted for 70% of all ered together with high annual human popula- single-species articles published in the years tion growth (> 1.5%) in the woodpecker-richest 1985–2004. I found a total of 33 articles (less countries, may lead to a rapid increase in the than 3% of the total) concerning woodpeckers in number of globally threatened species of Picidae Latin America where over half of all woodpecker in the near future. Cincotta et al. (2000) found species occur. Even if we take into account inac- that human population growth in global biodi- cessibility of some local, regional, and national versity hotspots is substantially above that of studies in the database used, the geographic developing countries in general, and predicted distribution of woodpecker studies seems to be that human-induced changes negatively affecting far from representative. The lack of knowledge biodiversity are likely to continue in these areas. on diets of 37 species in the most recent and in- Regional extinctions and population contractions depth global accounts on woodpecker life-histo- of woodpecker species related to socio-economic ries provided by Winkler and Christie (2002) is development resulting in forest loss and degra- a good illustration of this problem. What kinds dation have been described from temperate and of studies on woodpeckers are needed to be per- subtropical zones (e.g. Pettersson 1984, Virkkala formed and reported to the international commu- et al. 1993, Jackson 1994, Mikusiński & Angel- nity? Most importantly, more reports on wood- stam 1997, 1998). Since the rapid deforestation pecker assemblages from the areas identified as of areas with highest woodpecker diversity in continental or regional hotspots are required. the tropics is a relatively recent phenomenon, we These should cover the conservation status and have to consider a potentially large unrealised habitat requirements of particular species, their “extinction debt” (sensu Tilman et al. 1994) sensitivity to human impact, and their ecological as an important conservation issue in the near role in the ecosystems. Good examples of such future. studies are those provided by Styring and Ickes Some features of woodpecker distribution (2001), Lammertink (2004) and Schlatter and patterns and biology make them especially prone Vergara (2005). to rapid declines due to increase of human popu- Winkler and Christie (2002) identified gaps lation. First, woodpecker species occurring in in our knowledge on life-history traits and the low latitudes tend to have relatively small geo- conservation status of particular species. The graphic ranges (Blackburn et al. 1998) and there- keystone role of woodpeckers as excavators in fore several range restricted species may be more communities with secondary cavity users and susceptible to regional forest loss. Second, many with species that feed on sap or invertebrates woodpecker species are specialised foragers that exposed by woodpeckers should be assessed. do not attain high population densities but have The knowledge on habitat requirements of such relatively large home-ranges, and therefore a key-stone species are necessary for conservation viable forest population will need relative large planning in both primeval and managed forests. areas with a network of functional habitats. The It is possible that several woodpecker species in situation of the largest Camphepilus species is a the low latitudes will be useful focal/umbrella good illustration of this problem. Third, due to species. In terms of woodpecker conservation, their incompatibility with many forestry prac- it seems that emphasis should be put on larger tices concerning the lack of big and old trees, of species. The large species tend to be more often dead wood, and the reduction of compositional threatened (Fig. 5) due to their large area require- and structural diversity, woodpeckers may be ments, their specialisation on foraging substrate, unable to thrive in managed forests and forest and their need for trees with large dimensions for plantations. nesting and roosting. The literature survey on woodpeckers pro- The woodpeckers are an important part of vided striking results concerning the dispropor- forest ecosystems on five continents. This group tionate number of studies performed on species includes highly specialised species that are 94 Mikusiński • ANN. ZOOL. FENNICI Vol. 43 threatened by the recent and future deforestation Bütler, R., Angelstam, P. & Schlaepfer, R. 2004: Quantitative snag targets for the three-toed woodpecker, Picoides tri- of tropical and subtropical areas. At the same dactylus. — Ecological Bulletins 51: 219–232. time our knowledge on the majority of species Cincotta, R. P., Wisnewski, J. & Engelman, R. 2000: Human is quite limited. I urge all woodpecker research- population in the biodiversity hotspots. — Nature 404: ers to design and perform studies that can fill 990–992. the gaps in our knowledge. Such studies will Conner, R. N., Saenz, D. & Rudolph, D. C. 2004: The red-cockaded woodpecker: interactions with fire, snags, not only illuminate our understanding of wood- fungi, rat snakes and pileated woodpeckers. — Texas pecker biology and ecology, but will also con- Journal of Science 56: 415–426. tribute to the maintenance of forest biodiversity Conner, R. N., Hooper, R. G. Crawford, H. S. & Mosby, world-wide. H. S. 1975: Woodpecker nesting habitat in cut and uncut woodlands in Virginia. — J. Wildl. Manage. 39: 144–150. Cox, J. & Engstrom, R. T. 2001: Influence of the spatial Acknowledgements pattern of conserved lands on the persistence of a large population of red-cockaded woodpeckers. — Biol. Cons. Many thanks to Martjan Lammertink, Jean-Michel Roberge 100: 137–150. and Scott Brainerd for their comments on earlier drafts of Curran, L. M, Trigg, S. N., McDonald, A. K., Astiani, D., this paper. Hardiono, Y. M., Siregar, P., Caniago, I. & Kasischke, E. 2004: Lowland forest loss in protected areas of Indone- sian Borneo. — Science 303: 1000–1003. References Daily, G. C., Ehrlich, P. R. & Haddad, N. M. 1993: Double keystone bird in a keystone species complex. — Proc. Natl. Acad. Sci. USA 90: 592–594. 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