Spring arrival of passerine migrants in Iceland

Abstract

First sightings in Iceland throughout the 20 th century of four summer migrant passerines were studied for possible changes in arrival dates over time, and to relate arrivals to weather conditions in Iceland and in their probable wintering and staging areas. Arrival dates advanced considerably until the 1930s, as Icelandic seasonal temperatures increased. Temperatures and arrival dates changed much less in later years, when Icelandic temperatures showed no sustained trends. Since 1950, Redwings Turdus iliacus coburni have first been seen in the last week of March, Meadow Pipits Anthus pratensis and White Wagtails Motacilla a alba about 20 April and Wheatears Oenanthe o leucorhoa about 25 April. All four species were usually seen earlier when springs in Iceland were warm and wet, and after warm winters in southern Spain. Limited records of departures in autumn suggest that the mean lengths of stay in 1951-2000 were: Redwing 233 days, Meadow Pipit 164, White Wagtail 162 and Wheatear 144 days. Sightings of Redwings and Meadow Pipits, some of which winter in Britain & Ireland, were earlier after warm winters, and during warm springs, in central England. White Wagtails and Wheatears, wintering in Africa, showed no response to English temperatures. First sightings were most likely when winds over Iceland had easterly or southerly components. In 1951-1970 arrivals of Redwings and Meadow Pipits were earlier after winters in which the North Atlantic Oscillation index had been positive and high, but before and after that period no linkage was apparent. Most of these findings resemble those reported from north Norway, though the populations of at least three of the species are probably different. They are unlike the findings from Britain and western Europe, where dates of arrival have advanced most rapidly in recent years while winter and spring warming has continued. Recent studies in Britain and mainland Europe have revealed that the arrival dates of many species of summer migrants advanced during the second half of the 20 th century (

Flexibility in spring arrival of migratory birds at northern latitudes under rapid temperature changes

“…We analysed the changes in timing of spring arrival to assess if, and how fast, migrants respond to changing conditions when they have to make decisions of when to cross barriers on migration. Data on timing of migration in Iceland is scarce as no formal monitoring occurs (but see Boyd 2003, Boyd & Petersen 2008.…”

Spring arrivals of migrant waders in Iceland in the 20th century

“…The arrival times of waders in Iceland during the 20th century seem to have varied in much the same ways as those of the summer resident passerines (Boyd 2003). In the second half of the century, they failed to match the advances in arrival times shown by four of five species of geese (Boyd et al 2000), perhaps because of major differences in the performance of goose and wader populations.…”

“…The principal questions addressed here are: (1) have the many waders breeding in Iceland shown similar changes in arrival dates during the 20th century to those of the four summer resident passerines (Boyd 2003); (2) have high-Arctic passage migrants also changed their times of arrival; (3) have waders been influenced by the same (Boyer et al 1991(Boyer et al -2004. Other published data sources are referred to in the text.…”

“…The influence of climate on arrival dates is treated here in a very limited way. Variations in spring warmth in Iceland are described by mean monthly temperatures at Stykkisholmur, on the west coast, in March-May (Boyd 2003). Conditions in the British Isles, where many Icelandic waders overwinter, and over which most of them must pass in spring, are summarised by mean winter (December-February) temperatures in Ireland and in Central England, and by estimates of the daily state of the near-surface atmosphere in the spring months (after Lamb 1972 andMayes 1991).…”

Climate change alters the optimal wind-dependent flight routes of an avian migrant

“…Unsurprisingly, temperature and precipitation are the most commonly used variables in research on the impacts of climate change on migratory birds, as they determine the general suitability of habitats and breeding success. Variables related to air movement have also been considered in a handful of studies, but mostly due to their correlation with the timing of spring arrival of migratory birds [8][9][10][11]. Atmospheric currents, especially wind, play a significant role in shaping migratory routes and facilitating long-distance flight [12][13][14], particularly for species whose morphology and flight characteristics result in higher dependence on air movements for route selection, such as soaring raptors [15,16].…”