Most responsible cat owners take precautions when feeding wild birds in their gardens to reduce the likelihood of their pet catching and killing the birds, and these articles often give tips about how to do this. But at this time of year small birds need to be particularly wary of another predator in our gardens – the sparrowhawk, a bird of prey that is more commonly seen in urban gardens than any other. When spotting a sparrowhawk predating our first impulse may be to protect the small birds by frightening off the larger one, but spare a thought for the hawk.
March and April are the months when food supplies are at their lowest, and adult sparrowhawk mortality is at its highest – about a third of adults die each year with the most common cause being starvation. Their life expectancy is less than three years, whereas most other species of birds of prey live considerably longer.
Some people worry that sparrowhawks eat too many small birds and cause their populations to fall or even become endangered. Emotions can cloud the fact that the scientific research points to the contrary and long-term scientific studies have shown that sparrowhawks generally have no, or little, impact on garden bird populations.
A study conducted by the British Trust for Ornithology and funded by Songbird Survival looked at the relationship between populations of sparrowhawk and prey species over a period of 33 years.
This study concluded that for the majority of garden bird species (not least sparrows!) there is no evidence that increases in sparrowhawks are associated with their population declines. It is also clear that for the majority of declining species with unfavourable conservation status, population declines are due to factors other than predation (loss of habitat being a major one).
So, a sparrowhawk stealthily hunting its prey in our back gardens might be difficult for some people to watch, especially if there is a lengthy chase amid the shrubs and bushes before the final kill, but this is the stark reality of nature.