Diet Variability of Syrian Woodpecker Dendrocopos Syriacus Nestlings in the Rural Landscape of SE Poland
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NORTH-WESTERN JOURNAL OF ZOOLOGY 13 (2): 278-284 ©NwjZ, Oradea, Romania, 2017 Article No.: e161606 http://biozoojournals.ro/nwjz/index.html Diet variability of Syrian Woodpecker Dendrocopos syriacus nestlings in the rural landscape of SE Poland Jerzy MICHALCZUK* and Monika MICHALCZUK Department of Agrobiology and Environmental Protection, University of Rzeszów, Zelwerowicza 4, 35-601 Rzeszów *Corresponding author, J. Michalczuk, E-mail: [email protected] Received: 27. November 2015 / Accepted: 21. April 2016 / Available online: 26. June 2016 / Printed: December 2017 Abstract. The Syrian Woodpecker has expanded in Central Europe in the 20th century. The knowledge about nestling diet may allow better understanding on the colonisation process of anthropogenic tree stands by this species. In 2003-2006, we studied the nestlings’ diet composition and feeding frequency of 11 Syrian Woodpecker broods in SE Poland. The time nestlings spent in the nest was divided into six five-day intervals (pentads). Two four-hour observations were conducted during each pentad, and then the average number of feedings per one nestling in a clutch in 1 hour was calculated. Nestlings received food of animal origin more often - 1.70 feedings/1 nestling/1 hour, than of plant origin - 0.52 plant feedings/1 nestling/1 hour (proportion of 76.6 % and 23.4 % respectively). The birds fed their nestlings mainly Lepidoptera butterfly caterpillars, then the larvae of Coleoptera beetles, Cockchafers Melolontha melolontha and other arthropods (average of 0.70, 0.28, 0.15 and 0.57 feedings/1 nestling/1 hour, respectively). Between the first and sixth pentad of nestling life, the proportion of plant food in the diet increased from 1.6 % to 33.3 %. This most often consisted of walnuts Juglans regia and cherry Prunus avium or sour cherry Prunus cerasus fruits (average of 0.34 and 0.17 feedings/1 nestling/1 hour respectively). Individual broods were fed various foods and the diet varied according to the nestling growth. Dietary opportunism allows the Syrian Woodpeckers to produce broods in anthropogenic woodlots in Central Europe. Key words: broods feeding, dietary opportunism, primary hole nesters, afforestations Introduction anthropogenic habitats. This species feed mainly on items of animal origin, such as insects, for ex- The Syrian Woodpecker Dendrocopos syriacus has ample, Melolontha melolontha beetles, Lepidoptera colonized much of Europe in the 20th century butterfly caterpillars and arachnids Arachnida (Cramp 1985). The colonization of new area is ac- (Szlivka 1962, Ruge 1969, Marisova & Butenko tually proceeding dynamically on the east part of 1976). The birds also feed on food of plant origin. Europe, mainly on Russia territory (Zavialov et al. Often these are fruits, such as walnuts Juglans 2008, Michalczuk 2014). In the last three decades, regia, the fruits and seeds of cherry Prunus avium, it has also populated and expanded to south-east sour cherry Cerasus sp. and plum Prunus species, Poland (Tomiałojć & Stawarczyk 2003), becoming which are eaten mainly in autumn and winter a moderately numerous breeding species in the (Stevanović 1960, Szlivka 1962, Winkler 1973, region (Michalczuk & Michalczuk 2006, Marisova 1965). Syrian Woodpeckers also feed Michalczuk 2014, 2015). This species avoids dense their nestlings plant items (Szlivka 1962, Winkler forests, preferring anthropogenic tree stands 1972, Mitjaj 1986), which distinguishes this species (Glutz von Blotzheim & Bauer 1980, Cramp 1985, from other European woodpeckers that feed their Aghanajafizadeh et al. 2011, Michalczuk & young only animal food (Glutz von Blotzheim & Michalczuk 2011, Fröhlich & Ciach 2013, Bauer 1980, Cramp 1985). Michalczuk & Michalczuk 2016c, 2016d, 2016e). The aim of this study was to define the com- Probably Syrian Woodpecker can inhabit affore- position and seasonal variability of Syrian Wood- stations because its foraging behavior and diet pecker nestlings’ diet in rural landscape of SE Po- which are highly variable (Glutz von Blotzheim & land. Bauer 1980, Cramp 1985). Diet opportunism, which is characteristic for many birds species colonizing new habitats and areas (e.g. Skórka et Material and methods al. 2005, Neubauer et al. 2006, Skórka & Wójcik Study area 2008, Lill & Hales 2015), may determine the suc- The study was conducted in the agricultural landscape of cess of Syrian Woodpecker in the colonization of south-eastern Poland approximately 10 km west of the The Syrian Woodpecker nestlings’ diet in Poland 279 border with Ukraine (50o28 'N, 23 o40'E). This area (ap- items brought by the adults. Animal food was further di- proximately 305 km2) is characterized by gentle hills in vided into 4 groups of clearly identifiable food items. the range of 195 to 263 m above sea level (Kondracki Representing animal food were: larvae - mostly Coleoptera 2000). Crops (71%) and grassland (11%) prevail here, beetles, Lepidoptera butterfly caterpillars (larvae), Cock- small forests represent 4% of the area and usually are of chafer beetles Melolontha melolontha and "other arthro- hornbeam complexes, with a substantial share of Com- pods". The last group was comprised mainly of the adult mon Hornbeam Carpinus betulus and Oak Quercus spp. or forms of many insect species that were difficult to identify pine forests with a predominance of Scots Pine Pinus syl- because they were shredded at an anvil or of small size, vestris. The tree cover of built-up areas occupies 14% of such as aphids. Plant food was divided into 3 groups: the total study area. These are comprised mostly of tree Walnut Juglans regia, Cherry Prunus avium or Sour Cherry clumps, shaded avenues, hedgerows and parks, domi- Prunus cerasus, and "other", which included other plant nated by Willow Salix spp., Poplar Populus spp., Maple items such as flower petals. In many cases, adult birds Acer spp. and Ash Fraxinus spp. as well as the fruit trees were observed at foraging areas, such as anvils or ant- growing in preferred orchards: Apple Malus domestica, hills, in order to identify the food brought to nestlings. It Sour Cherry Prunus cerasus, Plum Prunus spp. and Wal- was easy to define because in many cases the foraging nut Juglans regia. Conifers are rarely found in the built-up sites were located near the nest holes. areas, represented by Spruce Picea spp., Larch Larix spp. or Pine Pinus spp. There were about 30-50 pairs of Syrian Statistical analysis Woodpeckers breeding in the study area (Michalczuk & To assess the variability of nestling diet, the intensity of Michalczuk 2006, 2015, 2016c). feeding of the particular components was evaluated in particular broods. The same approach was made while Observing the feedings of nestlings assessing the nestling growth. In this case, the intensity of The study was conducted from May to July in 2003-2006. feeding in the next pentads was assessed. In order to do The research was conducted on 11 nests (max. 3 nests per this, we used Kruskall-Wallis or one-way ANOVA test year). Observations were made of nestling feeding near (respectively with the Dunn and Tukey post hoc test). To the nest holes using 10x50 binoculars and a 30x50 spot- compare the general feeding frequency of animal and ting scope or photo and video cameras. Broods were ob- plant foods or to compare within the particular broods served while hiding, sometimes even only a few meters the U Mann-Whitney test or Student’s t-test was used. from the nest hole during the 6 pentads (five-day peri- The parametric tests were used if data had normal distri- ods), which is equal to the time nestlings remain in the bution or non-parametric ones were used if data had not nest (about 26 days, Holzer & Holzer 1982, Al-Safadi normal distribution. The statistical analysis was carried 2004, Mersten-Katz et al. 2012, Michalczuk & Michalczuk out using the StatisticaSoft 7.1 Pl package. All statistical 2016a, 2016b). Two cycles of observations lasting four differences were adopted at a significance level equal or hours each were conducted during each pentads. The less than 0.05. scope of one observation included morning feedings from dawn (approximately 4:00) to about 8:00. The second ob- servation included afternoon feedings, most often on a Results different day in a given pentad, from about 16:00 to the evening hours (around 20:00). Such a distribution of ob- The feeding intensity servations enabled us to capture the variation in the in- The average provision rate was 2.22 and was tensity of feedings associated with the time of day and the development of nestlings. In order to determine the num- ranged from 1.43 up to 3.74 (Table 1). The first ber of nestlings in the broods we have checked study pentad of life exhibited the lowest intensity of holes. For each brood feeding sample, the average num- feedings, with about 1.10 feedings (Table 2). The ber of feedings per one nestling in the clutch during one intensity of feedings increased significantly in the hour was calculated. For this purpose, the number of re- third pentad of life (post hoc Dunn test p < 0.001). corded feedings was divided by the four hours of obser- No significant changes in feeding intensity were vation and the number of nestlings in the clutch. The found in the remaining pentads (Table 2). feeding rate was presented in the form of No. of feedings per hour and nestling were used to compare the feeding intensity for different categories of food in successive The diet of animal origin pentads of nestlings’ life. Information was obtained for a Syrian Woodpeckers provide their nestlings total of 11 independent nests (from 2 up to 5 nestlings in a mostly with food of animal origin - 1.70 (Table 1). brood) on 4315 feedings, in a range of from 234 to 589 In the first pentad of life, the average frequency of feedings per brood.