Three birds in the bush

A few distant but instantly recognisable phrases were enough to reveal the presence of a male nightingale at the bottom end of the local nature reserve. It was early in the season, however, and this could easily have been a passage bird, just passing through. Fortunately, subsequent visits to the site have found the bird still present and seemingly holding territory in a piece of scrubby woodland that looks ideal for a future nesting attempt.

There is no mistaking the territorial claim of a nightingale; a richly varied and explosively loud song that has its own delicate rhythm and a confidence in its timing that echoes the very best of our jazz musicians. At times I have heard nightingales burst into song at the approach of a human observer who has, perhaps, strayed too close to the breeding site. The singing bird will often remain hidden from view, the song post buried deep within a tangle of bramble and other thick cover. On occasion, particularly ahead of dusk and early in the breeding season, the male may sing from more obvious perches and be more accessible to the would-be watcher. Once the eggs hatch, male song virtually ceases and the woods again fall silent, the pair becoming more skulking in habits and harder to locate.

The nightingale is not the only bird singing from the brambles at the moment, as both blackcap and garden warbler are busy delivering their rich, melodic warblings. The two species can be difficult to separate on the basis of their song and it always takes me a while to get my ear attuned once the first of these birds return to favoured breeding haunts. To my ear, blackcap song sounds as if it has been scripted, the bird clear in what it is going to sing and for how long; in contrast, the garden warbler seems more hurried, less organised and has the character of a songster who is making it up as he goes along.

Knowing the songs of all three birds is important to me as someone who surveys and monitors birds. All three species tend to make the most of the cover available and so are heard more often than they are seen. Repeated visits to study sites allows me to build up a picture of where the territories of these species are located and I can also use their calls to inform me of the likely stage of the breeding cycle. For example, blackcaps tend to alarm most readily just ahead of egg laying, then they go quiet until the eggs hatch, after which the harsh ‘tacc’ alarm returns, together with a rasping squeak. Such subtleties in behaviour are useful when working with these birds in the bush.

A croak in the bushes

I had never heard a Nightingale croak before! That such a renowned songster should utter an agitated amphibian croak came as a surprise. It was something quite unexpected, something that had passed me by all these years; an overlooked oddity that highlighted the gaps that remain in my experiences of our wildlife.

Oaken Wood is part of a much larger expanse of forest that spreads, lush and verdant, across the Surrey/Sussex borderlands. Owned by the Forestry Commission, Oaken Wood is managed as a reserve by Butterfly Conservation for its rich butterfly fauna, which includes such notable species as Purple Emperor, White Admiral and Wood White. It is also ideal for Nightingales, the thick regrowth providing the scrubby cover they favour for breeding.

According to Tony there were a dozen pairs or so here and, as we moved through the wood, snatches of male song echoed from the shadows. Restrained though they are, these short, measured flurries of song suggest that any moment the songster will break into an even louder and more resonant tune. Despite the association with thick cover, Tony noted that most of the nests would be within a couple of metres of the edge, something he had been taught as a boy by his father, an old boy ringer I’d met some years ago. Fewer than a dozen Nightingale nests are monitored each year (for the BTO Nest Record Scheme) but we hoped to add to that total through our visit to this site.

A soft hweet stopped us in our tracks – an off-nest female calling to her mate. Settling down just on the edge of the thicker cover and allowing our eyes to adjust to the gloom we watched and listened to see if we could follow her back to the nest. Tony took up a position further into the gloom, prompting the female to issue a frog-like croaking call. This meant that we were close to the nest and that it contained either eggs that were very close to hatching or chicks. Over the next hour, a patient game of watching ensued; every now and then I would glimpse the female, silhouetted against a patch of sunlight striking down through the gloom from a gap in the canopy. She was carrying food, so now it was certain that the nest contained chicks.

The patience paid off, the female returning again and again to the same patch of loose bramble cover, beneath which we found the surprisingly large nest, with its deep cup and five dark chicks. In the soft, droning gloom of the wood it seemed a very intimate moment and I felt privileged to have shared it with these wonderful croaking birds.