Journal of Environmental Biology

Influence of the alocal spring warming on the breeding phenology

in blackcp (Sylvia atricapilla) in Croatia

Author Details

Z. Dolenec

(Corresponding author)

Department of Zoology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, HR-10000,

Croatia

e-mail: dolenec@zg.biol.pmf.hr

P. Dolenec

High School Oroslavje, Ljudevita Gaja 1, HR-49243 Oroslavje, Croatia

Publication Data

Paper received:

21 July 2010

Revised received:

10 December 2010

Accepted:

08 January 2011

Abstract

Recent papers have shown that climate change affects many species, including birds. Several papers from different areas have devoted attention to the negative correlation between the dates of breeding and year, and also negative correlation between the dates of breeding and air spring temperatures. Recent work give some firm evidence for postulating causal relationship between spring temperature and laying dates. We used 31 years (1979-2009) of data from blackcap Sylvia atricapilla in Mokrice area, Northwestern Croatia to assess whether there has been any systematic change in breeding phenology through time. Among environmental factors possibly affecting the breeding date, consideration was given to mean monthly air temperatures (April-May). Over the past three decades, the breeding date of blackcap in our study population has changed significantly: They started breeding progressively earlier (11.77 days). Two regression analysis with laying date as criterion variable showed that spring temperatures can significantly predict variation of laying date and that there are also some other unknown factors which significantly explain variation of laying date. We conclude that blackcaps across northwestern Croatia are breeding earlier and that mean air spring temperatures is probably the most important factor causing it, among other factors.

Key words

Blackcap, Trend, Laying date, Spring temperatures, Croatia

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