Ornis Polonica 2019, 60: 1–15
The role of caches in the Eurasian Pygmy Owl Glaucidium passerinum during the breeding season
Abstract: Caches, or places where food is scatter hoarded for a short time, play a crucial role in winter for the Eurasian Pygmy Owls Glaucidium passerinum. Observations carried out in the Stołowe Mountains (SW Poland) at 25 broods in 1997–2006 indicate that they are important also outside the breeding season. A total of 183 caches, where owls deposited single prey items, were analysed. Food was hoarded near nest holes, almost exclusively by females, at the height of 0–30 m above the ground (mean 13 m) and at the distance of 3–70 m (mean 27.5 m) from the nest hole, mainly on spruce branches and tops of broken tree trunks. Females hoarded and retrieved prey items mostly at sunrise and sunset, which coincided with the timing of food delivery by males. Out of 191 prey items passed by males to females, 40% were stored in caches. Prey items were stored on average for 38 hours. A total of 29 aggressive encounters within a breeding pair were recorded, including 26 (90%) attacks of females against males. The author hypothesises that a strong aggression of a female towards a male near a nest hole is associated with a defence of stored food items.
Key words: Eurasian Pygmy Owl, Strigiformes, Strigidae, food, cache, catching place, female’s aggression towards the male
Ornis Polonica 2019, 60: 16–39
Numbers of ducks Anatinae during the breeding season at fish-ponds in Poland in 2016–2018
Abstract: Duck counts were performed in mid-May in 2016–2018 at carp fish-ponds in Poland. The area of 26 815 ha was surveyed (33% of the whole area of carp fish-ponds in Poland). A total of 35 426 individuals representing 17 species were found. The most abundant species were: the Mallard Anas platyrhynchos, Tufted Duck Aythya fuligula, Common Pochard A. ferina and Gadwall Mareca strepera, making up 97% of all ducks. A total of 4 754 female Tufted Ducks were recorded (the density of 1.8 females/10 ha of a pond area). Densities of Tufted Ducks were 3.3 times higher in southern Poland and near Kielce than in eastern and western Poland. In total 2 877 Common Pochards were counted (density of 1.1 females/10 ha). The maximum density was found near Kielce (2.7 females/10 ha), and it was 3–4 higher than in the east and west of Poland. A total of 865 female Gadwalls were recorded (density of 0.3 females/10 ha), and their densities were similar across the country. The exception was the area near Kielce, where the densities of the species were 2.5–3 times higher than in other surveyed sites. Sex ratio (proportion of males to females) in the Tufted Duck (1.21) was almost identical in all surveyed sites, while in the Common Pochard (2.55) varied considerably among the regions. In good breeding areas near Kielce the ratio was 1.61, whereas in western Poland, where the population of the species is declining, the sex ratio was estimated at 3.53. Among female diving ducks the Tufted Duck and Common Pochard were the dominants (61% and 37%, respectively), while the share of Red-crested Pochard Netta rufina and Ferruginous Duck A. nyroca was below 1%. The presence of numerous and large breeding populations in Kielce region and southern Poland is probably related to the absence of main predators of the species there (which are common in other areas of Poland): American mink Neovison vison and White-tailed Eagle Haliaeetus albicilla. Results of this survey can be referred to in future monitoring programmes of breeding ducks at fish-ponds in Poland.
Key words: fish-ponds, diving ducks, Common Pochard, Tufted Duck, Gadwall, sex ratio, monitoring of breeding ducks
Ornis Polonica 2019, 60: 40–46
Kleptoparasitism of the Jackdaw Corvus monedula and the Rook C. frugilegus during autumn and winter
Urszula Zaremba, Angelika Zbieć, Zbigniew Kasprzykowski
Abstract: Observations of kleptoparasitism by Jackdaws Corvus monedula and Rooks C. frugilegus were performed in autumn-winter 2015–2016 on the outskirts of Siedlce. A total of 259 cases of kleptoparasitism were recorded: walnuts that had been collected by Rooks were taken over by other Rooks or Jackdaws. Rooks were involved in 160 interactions (61.8%) and Jackdaws in 83 (32.0%), while both species attacked Rooks with food in 16 cases (6.2%). The number of individuals in a group of agressors did not differ between the two species. A total of 16.2% of Rook kleptoparasitic attempts were successful, while Jackdaws succeeded in only 7.2% cases. The success of kleptoparasitic attempt was significantly related to the size of a mobbing party in the Rook, but not in the Jackdaw.
Key words: Jackdaw, Rook, Common Walnut Juglans regia, interspecific interactions, competition for food
Ornis Polonica 2019, 60: 47–57
Abundance and distribution of the Mute Swan Cygnus olor in the Special Protection Area PLB200002 Augustów Forest
Grzegorz Zawadzki, Dorota Zawadzka, Anna Sołtys, Jerzy Zawadzki
Abstract: The number and distribution of the Mute Swan Cygnus olor in the Special Protection Area PLB200002 Augustów Forest (NE Poland) were studied on 64 lakes and 14 watercourses. In 2016–2018, 2–3 surveys were carried out on all the lakes of the area, from boat on the main rivers and by foot along smaller watercourses. Breeding Mute Swans were recorded on 76.6% of lakes, and only on 29% of surveyed watercourses. In total, 131–162 pairs of the Mute Swan were breeding annually in the studied area. The density of the breeding population was estimated at 9.7–12.1 pairs/100 km2 of the total area. Most of the population nested on lakes (90–110 pairs), and fewer on rivers (39–47 pairs). Single pairs occupied different habitats. The Czarna Hańcza River and Lake Wigry were the most important breeding sites of the studied species, with >20 nesting pairs recorded annually. The present data indicate that 2.1% of the national population of the Mute Swan breeds in the Augustów Forest, and thus the species should be considered as an object of protection in the SPA the Augustów Forest. Each year 170–250 non-breeding birds were observed within the study area. During the autumn migration swans were recorded most frequently on Lake Wigry; their numbers there were estimated at 150–200 individuals, and at 220–300 individuals in the whole SPA. Every year some individuals tried to spend winter on Lake Wigry and the Czarna Hańcza River.
Key words: Mute Swan, Cygnus olor, the Augustów Forest, Lake Wigry, density, numbers
Ornis Polonica 2019, 60: 58–65
The impact of plastic on birds
Ornis Polonica 2019, 60: 66–71
Caspian Plover Charadrius asiaticus – a new bird species for Poland
Paweł Malczyk, Anna Kleszcz, Grzegorz Orłowski
Ornis Polonica 2019, 60: 71–74
Brood of the Common Kestrel Falco tinnunculus in the nest of the White Stork Ciconia ciconia
Marek Murawski, Krzysztof Antczak