Marijan Govedič (Author), Franc Janžekovič (Author)

Abstract

Diet of the Great Cormorant Phalacrocorax carbo was studied by means of regurgitated pellets collected in March 1996 at night roost along the Drava river near Miklavž na Dravskem polju. Altogether, remains of 741 fish were found. Total weight of these fish was estimated at 115 kg. The diet consisted of 14 fish species (Chub Leuciscus cephalus, Nase Chondrostoma nasus, Barbel Barbus barbus, Grass Carp Ctenopharyngodon idella, Gold Fish or Prussian Carp Carassius auratus, Bream Abramis brama, Common Carp Cyprinus carpio, Danube Roach Rutilus pigus virgo, Roach Rutilus rutilus, Perch Perca fluviatilis, Ruffe Gymnocephalus cernuus, Striped Ruffe Gymnocephalus schraetzer, Zingel Zingel zingel and Pike Esox lucius). The diet was dominated by Perch (52.5% by number, 53.1% by mass) and Nase (14.0% by number, 22.3% by mass). Most of the fishes consumed by Cormorants belonged to the 18-22 cm (32.1%) size class. Average length of consumed Perch was 21.9 cm (median 21.5 cm, Q1-Q3: 18.9-25.2 cm) and 26.7 cm of Nase (median 25.3 cm, Q1-Q3: 22.3-31.9 cm). Average length of all prey in the diet of Great Cormorant was 21.3 cm (median 20.9 cm, Q1-Q3: 18.1-25.2 cm, min-max: 6.1-46.3 cm). Specimens of the first quartile constituted 6.4% mass of all prey, of the second and third quartiles 42.2%, and of the last quartile 51.3% mass of all prey. Length frequency distribution of the Perch, especially low proportion of small Perch in the Cormorants' diet, depended on standing waters' ice cover. Small Perches are abundant in standing waters, as they feed on plankton, which is most abundant there. In the winter of 1995/96 all standing waters in the Drava region were covered with ice and fishes in these waters were inaccessible to Cormorants. But as Ruffe and bigger Perches are not restricted to plankton diet, they also frequented flowing nonfrozen waters and were thus accessible to Cormorants' diet was probably higher than in feeding habitat, while the proportion of Nase, Barbel and Chub was probably lower than in feeding habitat

Keywords

ptice;kormorani;ribojede ptice;Phalacrocorax carbo;prehrana;zimska prehrana;analize;Slovenija;Sava;

Data

Language: Slovenian
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UM PEF - Faculty of Education
Publisher: Društvo za opazovanje in proučevanje ptic Slovenije
UDC: 598.8(497.4)
COBISS: 12972040 Link will open in a new window
ISSN: 0351-2851
Parent publication: Acrocephalus
Views: 711
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Other data

Secondary language: English
Secondary title: ǂThe ǂdiet of great cormorants Phalacrocorax carbo on the Drava river in the winter of 1995/96 (Slovenia)
Secondary keywords: birds;great cormorant;Phalacrocorax carbo;piscivorous birds;food;winter diet;analises;Slovenia;
URN: URN:NBN:SI
Type (COBISS): Not categorized
Pages: str. 11-19
Volume: ǂLetn. ǂ24
Issue: ǂšt. ǂ116
Chronology: 2003
ID: 1745738