Middle Spotted Woodpecker Dendrocopos Medius Research Articles

Review of Middle Spotted Woodpecker Dendrocopos medius distribution in the Karst region (W Slovenia), results of the first systematic census and first recorded breeding of the species in the area

Abstract The Middle Spotted Woodpecker Dendrocopos medius is a highly specialised woodpecker inhabiting mature deciduous forests. The presence of large mature oaks Quercus sp. is a very important factor determining the species' presence and distribution. In Slovenia it is more common in the eastern part, where it inhabits mainly lowland flood-plain oak forests. In other parts of the country it is more localised, as is the case in western Slovenia, where small isolated populations were recently discovered. In this paper we present the currently known observations of Middle Spotted Woodpecker in the Karst region (W Slovenia), the results of the first systematic survey and the first documented breeding of the species in this area. The survey was carried out on the 20 of March 2016 in the wooded hills between the villages of Senožeče and Veliko polje. Using playback method we recorded a total of 8 territorial woodpeckers, confirming our initial expectations about the species' abundance in that area. Breeding was also confirmed in the hills of Senožeče, an active nest-hole was found on 23 Apr 2017. On 18 May 2017 at least 3 juveniles successfully left the nest. Middle Spotted Woodpeckers have recently been observed also in other oak woodlands across the Karst and nearby areas, especially outside the breeding season. These areas include Lipica, Bazovica, the Brkini hills and the Gorica Karst. From summer 2016 onwards several observations of Middle Spotted Woodpeckers have been reported from Lipica, involving up to four different individuals. Repeated sightings in this area and the presence of suitable habitat suggest a probable breeding. The increased number of data in western Slovenia during the last decade might be a consequence of more frequent field visits by ornithologists. Moreover, the presence of the Middle Spotted Woodpecker in this part of the country might be linked to the gradual spreading of forests and the maturing of oak stands already present here. In the above-mentioned areas, further investigations and systematic censuses are therefore needed in the coming springs.

Do Oaks Quercus spp., dead wood and fruiting Common Ivy Hedera helix affect habitat selection of the Middle Spotted Woodpecker Dendrocopos medius?

Capsule The occurrence of the Middle Spotted Woodpecker in northern Switzerland was related to the availability of large oaks and standing dead trees, but not to trees with fruiting Common Ivy.

Population Increase and Habitat use of the Middle Spotted WoodpeckerDendrocopos mediusin the Aran Valley, Spanish Pyrenees

The middle spotted woodpecker Dendrocopos medius is a scarce species in northern Spain and is listed as endangered in Catalonia. We show a marked increase over a 24-year period in a population of the middle spotted woodpecker in the Aran Valley in the eastern Pyrenees in Catalonia. The population increased from two pairs in 1990 to 27 pairs in 2010, expanding south and east into two arms of the valley. The estimated breeding density in 2010 was 0.22 pairs/10 ha. Out of 26 surveyed forests, 54% were occupied by the woodpecker. There was no difference in occupancy rates between small, medium-sized or large forest areas. Breeding territories in mixed-deciduous forest were characterised by the presence of large-diameter pedunculate oaks Quercus robur. We conclude that the middle spotted woodpecker is expanding its range in the Pyrenees, probably due to an increasing presence of mature oak forests. The as-yet-small population size of the middle spotted woodpecker in northeastern Spain, combined with its relatively low density, suggests that forest protection measures should remain in place for this regionally vulnerable species.

Projected climate change causes loss and redistribution of genetic diversity in a model metapopulation of a medium‐good disperser

Climate change causes species ranges to shift geographically as individuals colonise new suitable temperature zones or fail to reproduce where climate conditions fall below tolerance levels. Little is known about the potential loss of genetic diversity in such dynamic ranges. We investigated the level and distribution of neutral genetic diversity in shifting metapopulations during three scenarios of temperature increase projected for this century and at various degrees of weather variability. We used an individual‐based and spatially explicit metapopulation model in which temperature zones were simulated to move across a fragmented landscape following different climate change scenarios. Although the connectivity between habitat patches allowed the species, modelled after the middle spotted woodpecker Dendrocopos medius, to move along with the shifting temperature range, existing neutral genetic diversity was lost under all three temperature increase scenarios. This was independent of the loss of individuals. The explanation for this effect is that only a part of the original genetic variation moved into the newly colonised habitat. Under increased weather variability the number of individuals and the number of alleles per locus were persistently lower. However, the pattern of changes in allele distributions under temperature zone shifts was the same under all weather variability levels. Genetic differentiation between populations had a tendency to increase at metapopulation range margins, but decreased again when population sizes increased in time. Increased weather variability led to increased variation around the mean genetic differentiation across the metapopulation. Our results illustrate the usefulness of more realistic models for studying the effects of climate change on metapopulations. They indicate that biodiversity monitoring indices based on species occurrence and abundance are not a good proxy for the trend in the level of genetic diversity. Further, the results underline the importance of conserving areas where species have existed for a long time as modern refugia for genetic diversity.

Predicting the occurrence of Middle Spotted Woodpecker Dendrocopos medius on a regional scale, using forest inventory data

The Middle Spotted Woodpecker ( Dendrocopos medius) is the bird species which Germany has the greatest global responsibility to protect. It is an umbrella species for the entire assemblage of animals associated with mature broadleaved trees, especially oak. Even though well studied in small to medium scale stands, the validity of habitat suitability analysis for this species in larger forests has not previously been proved. Aim of this study was to test suitability of permanent forest inventory plots for modelling its distribution in a 17,000 ha forest landscape and to derive habitat threshold values as a basis for formulating management guidelines. Based on 150 randomly selected 12.5 ha plots we identified mean age and basal area of oaks as the most important habitat factors using a backward selection logistic model. Internal validation showed an AUC of 0.89 and a R N 2 of 0.58. Determination of thresholds using maximally selected rank statistics found higher probability of occurrence in stands with a mean age >95 years. Above that age the probability increased again in stands with more than 6.4 m 2 basal area oak/ha. Our results show that widely available forest inventory data can serve as a valuable basis for monitoring the Middle Spotted Woodpecker, either within the framework of the Natura 2000 Network, or more generally in integrated forest management with the aim of providing suitable habitats for the entire assemblage of species on old deciduous trees, especially oak.

Reproduction of the Middle Spotted WoodpeckerDendrocopos mediusin the Nerussa-Desna Woodland, SW Russia, with Particular Reference to Habitat Fragmentation, Weather Conditions and Food Supply

The Nerussa-Desna woodland (south-western Russia) is one of the core areas for the Middle Spotted Woodpecker Dendrocopos medius, a habitat specialist restricted mainly to mature oak forests. Recent studies have shown a lower breeding density of the species in fragmented compared with continuous habitat. To evaluate reproduction as a possible mechanism underlying the fragmentation effects, we studied reproductive performance of the species in both continuous habitat and fragmented habitat in the forested landscapes of the Nerussa-Desna woodland. During 1997–2001, annual variation of reproductive indices in both continuous and fragmented habitat was insignificant. None of the indices was significantly lower in fragmented habitat though nestling losses were significantly higher in fragments. Timing of breeding in 2000 was later in fragmented than continuous habitat, probably due to differential landscape phenology. In fragments, fledging success in a year was inversely related to the mean amount of rain. On ...

Factors affecting the density of the middle spotted woodpecker Dendrocopos medius: a macrohabitat approach

The main goals of this study were to investigate the relationships between densities of the breeding population of the middle spotted woodpecker Dendrocopos medius obtained on 19 large-scale plots, and the share of different habitats and age of forest stands. An average crude density based on an area defined arbitrarily by observers was 0.66±0.43 territories/10 ha, while the ecological density based on an area including habitats potentially used by organisms reached 1.09±0.64 territories/10 ha. Stepwise multiple regression indicated that the crude density was negatively affected by the share of coniferous forest thereby explaining 50% of variation. The ecological density was negatively correlated with the percentage of young deciduous stands (0–40 years old). This variable explained 36% of the total variation. These results suggest that on the level of macrohabitat analysis, the share of unsuitable forest stands seem to play a major role in determining the density of the middle spotted woodpecker.

Sexual dimorphism and foraging niche partitioning in the Middle Spotted WoodpeckerDendrocopos medius

I investigated sexual differences in morphology and foraging behaviour in the nearly monomorphic Middle Spotted WoodpeckerDendrocopos medius.In the northeastern Swiss lowlands, radiotracked birds were observed from 1994 to 1996 between January and June. The sexes overlapped in all morphological characters, with males (n= 25) being on average larger than females (n= 17). Bill‐length and length of the crimson‐red crown patch were most useful to discriminate the sexes. Sex‐specific differences in foraging behaviour were found both within and between the prebreeding and breeding periods concerning the use of tree species, foraging techniques, relative height zones and living and dead substrates within a tree. Overall, both sexes had broader niches in the prebreeding than in the breeding period and niche overlap was larger during the latter period. Hence, sex‐specific differences were more pronounced in the prebreeding than in the breeding period, indicating different niche use of males and females in the two periods. These varying patterns of sex‐specific differences imply that niche segregation results from behavioural plasticity, probably based on dominance relationships between the sexes, rather than from sexual dimorphism.

Relative importance of habitat area, isolation and quality for the occurrence of middle spotted woodpecker Dendrocopos medius (L.) in Sweden

In a stepwise regression analysis, oak habitat area and habitat isolation were the most important parameters explaining numbers, density, regularity, and probability of presence in two successive years of middle spotted woodpeckers. No estimate of habitat quality contributed significantly to the equations. A 50% regularity of occurrence during the study period was found in oak areas of 75 ha. It is suggested that, for a small population, habitat fragmentation that gives rise to partially isolated subpopulations will make the population more vulnerable. The large area required by Swedish middle spotted woodpeckers compared with Central European ones, is believed to be a result either of an ‘extinction disequilibrium’ or of poorer habitats in the periphery of the distribution area of the species.

Extinction of an isolated population of the middle spotted woodpecker Dendrocopos medius (L.) in Sweden and its relation to general theories on extinction

A small population of middle spotted woodpeckers in southern Sweden became isolated at least 30 years ago. Since then the population has probably been rather stable at between 15 and 20 pairs. Censuses from 1967–1974 showed a stable population while a rapid decline, all the way to extinction, occurred in the period 1975–1983. In the period 1941–1978 no considerable changes in habitat area occurred. Losses of birds were correlated with number of cold days in winter. During the period 1975–1983 the reproduction of the birds was low, expecially because of many unsuccessful breeding attempts. Inbreeding depression is proposed to be the most probable factor causing low reproduction. If reduced fecundity is a general phenomenon in small and isolated populations, demographic models of extinction probabilities presented hitherto are too simple. Dispersal ability must be taken into account when planning reserve systems for endangered species.

Foraging behaviour of the middle spotted woodpecker Dendrocopos medius in Sweden

During winter and spring the oak Quercus robur, was the tree species most utilized by middle spoiled woodpeckers. In March, saptrees, mainly maples Acer platanoides, were preferred for a short period. In winter the birds foraged in the crowns of oaks but in spring they preferred lower stem parts. Dead branches were utilized more in winter than in spring. The birds mostly used a gleaning and probing technique, which may render the species more senstitive to severe weather conditions than other woodpecker species. Arthropods collected from trees were mostly spiders, beetles, thrips or springtails. The nestlings were mainly fed on scale insects and larvae of moths and sawflies. The oak habitat specialization is believed to be caused by competition for food with other gleaning forest birds. Food shortage might possibly occur during periods of bad weather, causing increased mortality.