Doprinos poznavanju obilježja jaja vijoglava Jynx torquilla

In this article I shall present data on the characteristics of the eggs of the Eurasian wryneck, Jynx torquilla, collected in north-western Croatia during the period from 1985 to 2018 using wood nestboxes. Nestboxes were primarily installed for investigation of Passerine bird species (tits Parus sp., tree sparrow Passer montanus and nuthatch Sitta europaea), but approximately one out of a hundred nestboxes per year was occupied by the Eurasian wryneck. In this study, 34 clutches in total were sampled during the first nesting in the study period, after all eggs had been laid. In this paper, oological data of the Eurasian wryneck in the south-eastern Europe area are presented for the first time. It is worth noting, however, that such data are scarce for the whole of Europe. Average number of eggs per clutch was 8.1 (from 6 to 10). Egg length ranged from 17.7 to 21.9 mm (mean = 20.1 mm), egg breadth from 14.2 to 15.9 mm (mean = 15.1 mm), egg volume from 1856.4 to 2668.9 mm³ (mean = 2347.5 mm³) and elongation index from 1.19 to 1.43 (mean = 1.33). Correlation between egg breadth and egg length was significantly positive. Relationship between egg volume and clutch size was not significant.U ovome članku prezentirana su osnovna obilježja jaja vijoglava Jynx torquilla na temelju podataka prikupljenih u razdoblju od 1985. do 2018. godine na području sjeverozapadne Hrvatske pomoću umjetnih duplji (škrinjica). Škrinjice su primarno postavljene za istraživanje gniježđenja ptica pjevica (sjenica Parus sp., poljskog vrapca Passer montanus i brgljeza Sitta europaea) ali bi godišnje na otprilike stotinu škrinjica jednu naselio vijoglav. Uzorkovana su ukupno 34 gnijezda tijekom razdoblja prvog gniježđenja, nakon što su snesena sva jaja. U ovome radu prezentirani su po prvi put oološki podaci vijoglava za području jugoistočne Europe, a vrlo je malo podataka i za Europu općenito. U gnijezdu je bilo prosječno 8,1 jaje (od 6 do 10 jaja). Jaja su bila duljine od 17,7 do 21,9 mm (srednja vrijednost = 20,1 mm), širine od 14,2 do 15,9 mm (srednja vrijednost = 15,1 mm), volumena od 1856,4 do 2668,9 mm³ (mean = 2347,5 mm³), a indeks oblika jaja od 1,19 do 1,43 (srednja vrijednost = 1,33). Korelacija između duljine jaja i širine jaja je pozitivno značajna dok između volumena jaja i broja jaja u gnijezdu nije zabilježena signifikantnost