Take on Nature: Chiff-chaff brings to mind spring's changing patterns

Phylloscopus collybita – tiuf teaf in Irish – is a common summer visitor to our deciduous woodlands

RECENTLY, just as light was breaking through with snow falling on the local brae, two blue-tits defied each other, and winter’s stubbornness, with vigorous territorial song, a war of spring words, each declaring this was their patch.

Spring is difficult to define. For many in rural Ireland it arrives on February 1, St Brigid’s Day. Meteorologists have little time for celestial patterns or historical precedent and simply set March 1 as the first day of spring, while astronomers hold fast to the vernal or spring equinox as the beginning of the season, which this year will occur on Tuesday March 20.

Like most people, I watch and listen for those tell-tale signs of spring which confirm beyond doubt the season has arrived. Signs may include the first appearance of frogspawn, swelling tree buds, an unfurling leaf, a lone swallow or the liquid notes of the blackbird.

For me the arrival and first call of the chiff-chaff confirms that spring is well and truly here with no turning back. Weighing just nine grams and having made its arduous journey from the Mediterranean basin, I trust the bird’s timing.

Phenology is the scientific study of the timing of these types of recurring life-cycle events in plants and animals. With long-term observations over decades of natural ‘phenological’ events such as first flowering, insect hatching and bird migration, it becomes possible to identify important patterns between these events and the external forces, like rising temperature, which influence them.

This sensitivity to temperature change means the study of phenology is an important tool in climate change research. Indeed, phenological data from across Europe, including Ireland (Menzel et al, 2006) was used in the Intergovernmental Panel on Climate Change’s (IPPC) Fourth Assessment Report to demonstrate to global policy-makers the impact of climate change on life cycle events of plant and animal species.

The scientific paper 'Irish phenological observations from the early 20th century reveal a strong response to temperature' (Carroll et al, 2009) records that the spring migrant bird arrival dates of "five out of seven species analysed’’ in Ireland were much earlier during the period 1969-1999 than for the period 1927-1947.

It also states that three of these were "significantly earlier" – the house martin, sedge warbler and swallow. The authors conclude by saying, "there has been advancement in phenological events in the Irish countryside during the 20th century that is strongly correlated with increasing air temperatures. The range of species influenced is broad and includes insects, summer and winter migratory birds, flowering plants and trees.’’

Data from BirdTrack, a partnership between BTO, RSPB and Birdwatch Ireland also shows that swallows are now arriving in the UK "about 20 days earlier than they did in the 1970s".

Returning to the chiff-chaff, phylloscopus collybita or tiuf teaf in Irish, a common summer visitor to our deciduous woodlands, its distinctive "chiff-chaff’’ song is repeated five or six times and is heard any time from early March.

A slim, graceful member of the warbler family and sometimes called the Sally picker in Ireland, the bird is a dull greenish colour above with slightly paler underparts and dark legs. Similar in appearance to the willow warbler, the chiff-chaff feeds mostly on insects and invertebrates.

English author Alan A Milne, best known for his books about the Teddy bear Winnie-the-Pooh, wrote, "Why does a silly bird go on saying 'chiff-chaff' all day long? Is it happiness or hiccups?" When I hear that first chiff-chaff sing, I’ll take it as a call of happiness at spring’s arrival. Not much longer to wait now.

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