FIRST SWALLOWS & HAWTHORN BLOSSOM

Swallow Information

Some migrant birds are considered harbingers of spring and are readily recognised by sight or by song. The swallow (Hirundo rustica) is readily observed, is associated with human habitation and is most active when insect production rises to the level that makes aerial feeding possible. In terms of indicators, the first sighting of the swallow may seem on a par with the first hearing of the cuckoo, but the latter is, in fact, less closely related to spring temperatures.

The swallow is a long distant migrant, overwintering in southern Africa. Fine tuning of its arrival time has been shown to be temperature related, probably because the aerial insects on which it depends must have emerged by the time the swallow arrives. If food supplies en-route are restricted it is likely that the swallow will slow or halt its northwards passage.

The time series shows a pattern of late arrival in cold springs, for instance in 1986, and the reverse in years with warm springs. There is evidence of a trend towards earliness in swallow arrival dates since 1970 in response to warmer springs.
The relationship suggests that a 1EC increase in spring temperature is associated with 2-3 day earlier appearance of swallow. Thus, in the event of climate warming we might expect swallows to be seen earlier and more often in March.

Hawthorn

Hawthorn is at its most prominent in the landscape when it blossoms during the month of May, and probably the most popular of its many vernacular names is the May-tree. As such, it is the only plant which is named after the month in which it blooms. It has many associations with May Day festivities. Though the tree now flowers around the middle of the month, it flowered much nearer the beginning of the month, before the introduction of the Gregorian calendar in 1752.

The blossoms were used for garlands, and large leafy branches were cut, set in the ground outside houses as so-called May bushes and decorated with local wildflowers. Using the blossoms for decorations outside was allowed, but there was a very strong taboo against bringing hawthorn into the house. In the early 1980s the Folklore Society's survey of 'unlucky' plants revealed that 23% of the items referred to hawthorn, more than twice as many instances as the second most unlucky plant. There was the belief that bringing hawthorn blossom into the house would be followed by illness and death, and there were many instances of hapless children being scolded by adults for innocently decorating the home. Mediaeval country folk also asserted that the smell of hawthorn blossom was just like the smell of the Great Plague in London. Botanists later discovered that the chemical trimethylamine present in hawthorn blossom is also one of the first chemicals formed in decaying animal tissue. In the past, when corpses would have been kept in the house for several days prior to burial, people would have been very familiar with the smell of death, so it is hardly surprising that hawthorn blossom was so unwelcome in the house.