So I am four months into my research and the morning are getting earlier but it is great fun, even a little scary being out in the middle of a wood in the middle of the night effectively! I think I’ve watched too many horror movies to be honest.
So what have I discovered so far? Well one thing I did not realise was that birds sing earlier during the day the further into the year you go. So in January the peak was 1 hour after sunrise, February half an hour after sunrise and for both March and April at sunrise. So the below graph shows the half hour counts before and after sunrise against the total number of birds singing along the same 500 meter section of woodland.
Also it is clear that some species peak early. Song Thrush peaked in February with 41% of the total birds recorded and peak time is at dawn. For January to April 74% of all birds were singing between half an hour before dawn to one and half hours afterwards (24% singing at dawn). The peak for Song Thrush is early in the season and early in the day, so any surveys are the first two hours of daylight would only record 25% of all singing birds.
So given potential for geographical variation in the timing of species and lets say the more north you go the later the sunrise and temperature is lower which may cause birds not to start breeding later then the timing of your breeding bird survey it critical to ensuring you cover all the species.
Currently I have recording Tawny Owl being vocal after the first half an hour of daylight. The peak for them is one hour to before sunrise to sunrise. This shows starting early will pick up breeding Tawny Owls as well. It would interesting to be present somewhere other nocturnal species frequent such as Eurasian Woodcock.
Comments