Swifts, Swallows and Butterflies: August in North Yorkshire

August, North Yorkshire, England

Just a few weeks ago, the fields round here were filled with cabbage white butterflies dipping and fluttering over the drying heads of oil seed rape, spilling over into the garden and warming themselves on the paths. Today, they are abundant- everywhere- yet not the plague they were. The biologist in me is left wondering what has brought about this reduction- if it is the chill brought on the first tendrils of Autumn- or something with more feathers.

We have already had the first fungi on the lawn – chunky bright orangey-yellow caps of the “witch’s hat mushroom”, Hygrocybe conicus- by my identification, which my parents, who are in their sixties, see as proof of that Autumn has, indeed, arrived and, beyond that, as evidence of the slipping seasons “these days”. They may be right, of course: there is certainly evidence of the seasons slipping: but, as my trusty pocket fungus guide assures me, the witch’s hat is not it. Like its still-brighter cousin- the yellowy-green coloured “parrot toadstool” it is –and always has been- a summer and autumn species.  

The last month has also brought unusually large numbers of swifts and swallows. Although I’d love to describe a summer filled with swallows soaring amongst the fluffy blue clouds and endless, dreamy afternoons, it is more truthful to say that the portions of sunshine in our blustery, sunshine-and-showers summer have been marked with swallows and their smaller, darker colleagues, swifts. In fact, the two species are only distantly related: the swifts being an off-shoot of the hummingbird family: Apodidae and the swallows being part of the Hirundinidae family and, consequently, more closely allied to tits and to Asian and African white-eyes. Here, in Yorkshire, swifts also rejoice in a plethora of colourful folk-names- two of the better ones being “devil shrieker” (on account of its piercing call) and “devil’s bitch”.

Swifts and swallows differ in ancestry, but share their dining habits: snapping insects on-the-wing with their short, wide bills. With such an abundance of avian predators, it seems likely that many of our profusion of cabbage whites may have been carried off in their beaks. However, ecology is more complex than it appears and trying to pinpoint a plague or dearth of anything to any single cause requires us to tease a straight answer from a tangled net of interacting biological and environmental factors. If this sounds like a prelude to a call for endless government-funded ecological research, then I would argue it is more of a reason for it. It will be sometime before we fully understand ecological webs and, with them, Yorkshire’s current pleasant plague of butterflies. 

This article was one of a series first drafted for a book in Aug 2009, however, the bookplan evolved and the chapter was axed. This is the first time it has been published. You can read more of Victoria’s work in “Practical Reptile Keeping” magazine and on her website.