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| The Cuckoo | The Swift |
Phenology is the study
of seasonal changes in animals and plants e.g. the first and last blooming
dates of wild flowers, the first and last dates for migratory birds.
BNA issues an annual sheet requesting phenological records of 55 species concentrating
on common flowers, birds, mammals, amphibians and insects, especially butterflies
and moths. Species include common frog, swifts, cuckoo, coltsfoot and hedgehog.
Contributors are not expected to cover all species within their 10 mile locality
area.
The phenological report is made available each year by BNA in one of its publications.
This includes a summary of the data on the selected species and a concise
month by month description of the overall seasonal changes including the influence
of weather and special features for the year.
Phenological data was pioneered in the journals of the Reverend Gilbert White
and remained popular during the nineteenth century. BNA has continued the
tradition for the twentieth century. As we are entering a period of considerable
climatic change and are looking to evidence of plant and animal life, the
BNA phenological report, as a long term study, helps to monitor change.
Global warming is a current
event very much in the minds of scientists, economists, naturalists etc. and
there are two schools of thought:
a) it will happen and
b) it will not be more than a short term warming as happens from time to time.
Phenology a comparative countryside calendar - Notes on Comparisons and Changing Times
Phenological report recording form If you live in the UK and would like to take part this year, please print off this form, add your own details and send it, with your records, to the organiser Michael Wallis.
The results of phenological survey 2002
by ROGER TABOR, BNA Chairman
The data that the BNA have gathered though the length of this century does not just help with climate implications, but gathers information that can be helpful in understanding patterns of behaviour in particular species. Using the records of arrivals on a county by county basis for the BNA's first 75 years I was able to compile both arrival graphs and patterns of movement across the country for Cuckoos and Swifts.
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| The Cuckoo | The Swift |
The histogram of cuckoo arrivals shows the likelihood of hearing the first cuckoo across the country rather than the first arrivals, as cuckoos are more heard than seen! The cuckoo's two note call is perfusive and unambiguous enough to allow particular dependence on the results. In recent years there has been concern that spotters of the first cuckoo of the year may have confused the calls of the collared dove and the cuckoo, and that some apparently early arrivals submitted to "The Times" may derive from the wrong bird. However due to the long term overview of the BNA findings this has had minimal impact on them, as the first pair of collared doves to nest in Britain did so in 1955, and their numbers have only built up in more recent years. Consequently when the BNA's findings on this were first published in its magazine "Country-Side", then "The Times" picked up the story and admonished those of its readers that might be too quick in writing in with claims for the first cuckoo that in the BNA's findings they now had a means of checking the probability of the claim!
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I found as I plotted out the data that the considerably faster-flying swift lived up to its name and on its arrival covered the country in half the time taken by the cuckoos. The sudden rush of screaming scimitar-winged birds flying into any village is an event that is looked for each year, and is singularly unambiguous.
The national mean date of arrival of the swift was 2 May [n =486, SD =7.7 days], and that of hearing the cuckoo was 19 April [n =618, SD =7.9 days]. The dates shown on the maps are the mean regional arrival dates over the years. The south coast maps are shown with smaller regions which reveals that initial penetration of the coast by both birds is centrally, although the cuckoo spans also a little to the east.
Please let us know when you hear your first cuckoo and see your first swift in 2001.
I and the BNA would like to thank all those that have helped in collecting the data over the years, as well as those that have helped me in the gathering and analysing this information from BNA records.
ROGER TABOR
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