Hybrids of Great-spotted and Syrian Woodpeckers

Formerly, these two woodpeckers did not coexist (Syrian Woodpeckers inhabited the Middle East, whilst Great Spotted was widespread in the temperate and boreal forests of Eurasia). However, at the end of the 19th century, the Syrian Woodpecker began to expand its range into Europe, first settling in the Balkans, then Central and Eastern Europe, before reaching parts of Western and Northern Europe (Michalczuk 2014). In the Middle East, the Syrian Woodpecker mostly inhabits open woodlands and groves. In the newly settled European range (especially in Central Europe), this species has become synanthropic, occurring mainly in rural and urban landscapes.

Field observations have indicated that a small number of ‘pied’ woodpeckers observed in Central Europe (first in the Pannonian Basin, later also in Poland and the Czech Republic) show features intermediate between the Great Spotted and the Syrian. These observations resulted in documented breeding records of mixed pairs and the identification of hybrids. An early summary can be found in the work of Gorman (1997, 1999, 2004), while for Poland it is described by Dudzik and Polakowski (2011). Still, information on the hybridization of these two species has often been rather general, based on random observations and the mechanisms and circumstances in which these birds may interbreed have not been adequately explained.

The issue of hybridization between the Great Spotted and the Syrian has become the subject of research in recent years. These studies were aimed at recognizing the scale of the hybridization of these two species, mainly in urban populations. Research showed a partial displacement of the ecological niches of both species (Michalczuk and Michalczuk 2016a, b, Kajtoch and Figarski 2017, Figarski and Kajtoch 2018a), differences in behaviour (Figarski 2018) and above all, descriptions of the frequency and structure of mixed pairs and hybrids (Figarski and Kajtoch 2018b).

In short, these studies showed that both species avoid nesting in the same place and that the share of mixed pairs reaches 5% in urban populations. On the other hand, the frequency of the occurrence of hybrids may have depended on the identification method used in the field, as on average, 4% of birds were described as hybrids, while among dead specimens (hence examined closely), the share of hybrids increased to 7%. However, these estimates turned out to be underestimated when molecular methods were used (Michalczuk et al. 2014, Figarski and Kajtoch 2018c, Gurgul et al. 2019), which resulted in the identification of 20% of urban birds as hybrids. Further research showed that successful breeding is possible even between two hybrids (Kajtoch and Kusal 2022). In addition, the latest data indicates that the Syrian Woodpecker is decreasing in southern Poland (Michalczuk and Michalczuk 2015, Kajtoch, unpublished), while the Great Spotted Woodpecker is increasing significantly across the whole country (the Monitoring of Common Breeding Birds in Poland). In the rest of the European Union, the trend for this species is uncertain - it has stable or growing populations in the Balkans and the Pannonian Basin, while changes in abundance are undetermined in other Central European countries (link). Changes in the number of  Syrian Woodpeckers in Central Europe are most likely associated with three factors: i) the disappearance of relevant trees (removal of greenery in cities and villages), ii) competition with the Great-spotted Woodpecker, iii) hybridization. Due to the fact that hybrids are viable and fertile, in some places, hybrid populations may be established, but difficulties in detecting and identifying hybrids make this phenomenon virtually unrecognized. Hybridization can result in inconsiderable consequences for the Syrian Woodpecker population, especially at the edge of its range. It should be noted that this is a species protected by the Birds Directive of the EU (Natura 2000 areas have been created for its protection). Understanding the scale, mechanisms and consequences of hybridization may therefore be of significant practical importance for the protection of the Syrian Woodpecker. In addition, it is an interesting phenomenon that allows a better understanding of the mechanisms of speciation and hybridization in birds in general.

Methodology

Transects can be linear, broken or U-shaped, depending on the topography of the area and the accessibility of roads and trees. If it is planned to designate several transects in a given area, they should be separated from each other by a minimum of 500 m. Transects should be controlled on foot during the day (at least 30 minutes after sunrise and at least 30 minutes before sunset, but preferably not around noon).

Controls should be performed only in good weather conditions: no rain or snowfall, no wind, and no fog or smog which limits visibility above 50 m.

It would be optimal to designate a transect (or transects) in both rural and urban areas in a given area of the country. Methodically, it is most advantageous to determine transects in both urban and adjacent rural areas. If an observer plans several transects, or there are several observers operating in a given area, it is advisable to plan the transects on the basis of a gradient: city - suburban area - rural area.

The choice of the location of the transect is up to the observer. If you are interested in participating, but do not know about the location of potential transects, please contact the coordinator.

During territorial surveys (T1 and T2), it is advisable to use playbacks of Syrian Woodpecker calls (see Michalczuk et al. 2011) at points distant every 300 m, i.e. at 8 points located at a distance from the starting point: 150 m, 450 m, 750 m, 1050 m, 1350 m, 1650 m, 1950 m, 2250 m. Assuming audibility within a radius of 150 m, the entire transect will cover approximately 2.4 km. Such stimulation should consist of sounds according to the following scheme: drumming (1 min) - listening (1 min) - contact voice (1 min) - listening (1 min) (mp3 file attached). In the case of bird reacting, further playback use should be abandoned and focus made on observation and documentation. Assuming a walking speed of 3 km / h between the points, the total control should last up to 1.5h (k. 0.5h of stimulation and listening + k. 1h of moving between points). A slow walking speed is necessary because during listening and walking one should look for birds calling, arriving, foraging, excavating, etc. All woodpeckers with the appearance of Great Spotted and Syrian should be looked for and recorded. Additionally, the presence of other species of woodpeckers and starlings (for each of the stimulation points) should be noted.

During the nesting survey (N), Observers should walk through the transect at a similarly slow speed and stop at the places where any woodpeckers were observed during the territorial survey, and wherever a cavity was found or young birds were heard calling (from a cavity or from a tree). The nesting survey should only be performed when woodpeckers (Great Spotted, Syrian, hybrids) were detected during at least one territorial survey.

If two parallel transects are undertaken in a given area, time should not be wasted searching for woodpeckers between transects (it is better to spend time systematically surveying a larger number of transects).

Whenever possible, each woodpecker recorded should be photographed. Each individual should be characterized according to species and sex (adult birds only), and behaviour should also be recorded (details below). Particular attention should be paid to the simultaneous observation of pairs, two or more birds seen at the same time, as well as family groups with juveniles. In addition, it should be verified whether a given individual has the features of a hybrid (this mainly concerns adult birds). It is necessary to record the place where the photos were taken (preferably with the number of the transect and the playback location) so that it is possible to link the photos with the places of observation.

Observations should be recorded on the attached form, and next re-write to sheets in attached excel file. 

Maps facilitating orientation in the field and the coordinates of the playback points will be prepared after the coordinates of the beginning and end of the planned transect have been reported or a declaration of participation with a request to designate a transect in a selected region of the country to the coordinators.

Features of  hybrids  (Gorman 1999):

• Much white in the outer two rectrices.

• White spots or bars on the third rectrix.

• Much white on the undertail.

• Presence of, or part of, a post-auricular stripe.

• Dark red vent and undertail tail coverts.

• Black lower extension to the lateral neck stripe touching the mantle or scapulars.

• White tips to the outer primaries.

• Substantial amounts of white in flight feathers.

• Presence of, or hint of, a fourth or fifth white wing-bar.

• Nasal bristles dark or buff rather than white.

• Small red nape patch.

• Call inconsistencies, i.e. Syrian-like birds calling like Great Spotted or vice-versa.

For observers – a step-by-step guide

Additional information:

References

Dudzik K., Polakowski M. 2011. Przypadki łęgów mieszanych oraz problematyka identyfikacji mieszańców międzygatunkowych dzięcioła białoszyjego Dendrocopos syriacus i dzięcioła dużego Dendrocopos major w Polsce. Chrońmy Przyrodę Ojczystą 67:254–260

Figarski T. 2017. Contrasting seasonal reactions of two sibling woodpeckers toplayback stimulation in urban areas — implications for inventory and monitoring of the Syrian woodpecker. Behaviour 154: 981–996.

Figarski T., Kajtoch Ł. 2018. Differences in habitat requirements between two sister Dendrocopos woodpeckers in urban environments: implication for the conservation of Syrian Woodpecker. Acta Ornithologica. 53: 23–36

Figarski T., Kajtoch Ł. 2018. Hybrids and mixed pairs of Syrian and great-spotted woodpeckers in urban populations. Journal of Ornithology 159: 311-31

Gorman G. 1997. Hybridisation by Syrian Woodpeckers. British Birds 90:578

Gorman G. 1999. The Identification of Syrian Woodpecker. Alula 3: 82-88. 

Gorman G. 2004. Woodpeckers of Europe. A Study of the Picidae. Bruce Coleman: p. 108.

Gurgul A., Miksza-Cybulska A., Szmatoła T., Jasielczuk I., Semik-Gurgul E., Figarski T., Bugno-Poniewierska M, Kajtoch Ł. 2019. The evaluation of genotyping- by-sequencing for population genetics of sibling and hybridizing birds: example of Syrian and great-spotted woodpeckers. Journal of Ornithology 160: 287–294

Kajtoch Ł., Figarski T. 2017. Comparative distribution of Syrian and Great spotted woodpeckers in different landscapes of Poland. Folia Zoologica. 66: 29–36

Kajtoch Ł., Kusal B. 2022. The first case of a successful brood from a double hybrid mixed pair Dendrocopos syriacus x D. major (Picidae). Ibis doi.org/10.1111/ibi.13096

Michalczuk J., Michalczuk M. & Cymbała R. 2011. The usefulness of various methods of monitoring the population size of the Syrian woodpecker Dendrocopos syriacus. Ornis Pol. 52: 280–287.

Michalczuk J. 2014. Expansion of the Syrian Woodpecker Dendrocopos syriacus in Europe and Western Asia. Ornis Polonica 55: 149-161.

Michalczuk J., McDevitt A.D., Mazgajski T.D., Figarski T., Ilieva M., Bujoczek M., Malczyk P., Kajtoch Ł. 2014. Tests of multiple molecular markers for the identification of Great Spotted and Syrian Woodpeckers and their hybrids. Journal of Ornithology 155:591–600

Michalczuk J. & Michalczuk M. 2015. Decline of the Syrian woodpecker Dendrocopos syriacus population in rural landscape in SE Poland in 2004-2012. Ornis Pol. 2: 67–75.

Michalczuk J. & Michalczuk M. 2016a. Habitat preferences of Picidae woodpeckers in the agricultural landscape of SE Poland: is the Syrian woodpecker Dendrocopos syriacus colonizing a vacant ecological niche? North-West. J. Zool. 12: 14–21.

Michalczuk J. & Michalczuk M. 2016b. Coexistence of Syrian woodpecker Dendrocopos syriacus and great spotted woodpecker Dendrocopos major in nonforest tree stands of the agricultural landscape in SE Poland. Turk. J. Zool. 40: 743–748.