Breeding biology of the house sparrow (Passer domesticus) in the Faroe Islands / Nøringin hjá føroyska gráspurvinum (Passer domesticus)

Eyðfinn Magnussen, Jens-Kjeld Jensen

Abstract


Abstract: The breeding biology of the Faroese house sparrow (Passer domesticus) is described based on the results from nestlings that were ringed just before they were fledging. By means of dates and numbers, the beginning and duration of the breeding seasons are determined and the reproductive output is estimated. Our study has shown that Faroese house sparrows produce two, occasionally three, broods annually. Overall, eggs of the first, second and third clutch are normally laid in the beginning of May, in the middle of June and in the beginning of July, respectively. In a season, a female produced 6.3 nestlings, on average. For the whole period, the average brood size was 3.5 nestlings. During the first part of the time series (1985­1989), the breeding season became earlier each year, but then to be later again in the years 1990 to 1992. The first clutch was laid more than five weeks earlier in 1989 than in 1985 and the second clutch almost seven weeks earlier.

 

Úrtak: Árini frá 1985 til 1992 vóru tilsamans 347 gráspurvaungar (Passer domesticus)  merktir í bygdini Nólsoy, beint áðrenn teir vóru floygdir. Við at nýta dagfestingina tá ungarnir vórðu merktir og talið av ungum er ásett, nær og hvussu ofta gráspurvurin verpur og hvussu nógvar ungar hann fær hvørja ferð. Kanningarnar vísa, at føroyski gráspurvurin verpur tvær ferðir um árið, viðhvørt tó tríggjar ferðir: Fyrstu urptin er í byrjanini av mai mánað, tann næsta er um miðjan juni og triðja urptin í byrjanini av juli mánað. Hvør bøga fær í miðal 6,3 ungar um árið. Í miðal vóru 3,5 ungar í hvørjari urpt. Úrslit okkara vísa, at tey fyrstu árini varp gráspurvurin fyrr og fyrr, fyri hvørt árið. Hetta broyttist tó tey seinru árini sum kanningin vardi: Í 1989 vórðu fyrstu eggini vorpin meira enn fimm vikur fyrri enn í 1985, og næstu urptin næstan sjey vikur fyrr.


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DOI: http://dx.doi.org/10.18602/fsj.v58i0.65

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