PERHAPS one of the most pleasurable aspects of working on the district's nature reserves, despite the uncomfortably hot weather, is coming across some of the scarcer species to occur.

Recent sightings include a summer visitor which has suffered significant population declines over the last half century, the spotted flycatcher.

Arriving in Britain from mid April, though mostly in May, these birds may be seen by some as archetypal "little brown jobs" and are often overlooked.

However, they make up for their drab appearance with captivating behaviour.

As I walked along Hoo Brook in Spennells Valley one evening, I noticed the upright posture of a perched bird, before it quickly sallied forth in pursuit of some unseen flying insect.

It then pirouetted in mid-air, seizing the hapless prey in its delicate bill, before returning to the same favoured perch to swallow it after disposing of the wings. This neat trick was then repeated several times in a few minutes before I walked on.

Spotted flycatchers breed throughout most of Europe, nesting in open aspect tree holes, wall crevices and such like. They can also be encouraged to use open-fronted nestboxes, particularly if sited on a wall covered with ivy, or some other creeper.

However, as these birds are among our later arriving migrants, many suitable sites may be already occupied by other species, such as robins.

The stretch of brook within the reserve abounds with insect life, making ideal foraging territory, although it's not known whether or not the birds have actually bred on the site this year.

In addition to drought conditions in the sub-Saharan wintering areas, wetter, colder springs on the breeding grounds are thought to have contributed to the worrying declines.

Crucially, low temperatures during the month of May inhibit insect activity, resulting in prey being harder to catch. This particularly affects the females when they need a reliable food supply to bring them into breeding condition. A good way to understand the relationships between various organisms like insects and birds is to imagine a pyramid-shaped stack of cans in a supermarket.

If a child removes one, the pile may remain standing, but if one is taken from the bottom row, the whole stack may come crashing down.

The pile of cans represents life on earth, and illustrates just how careful we (the child) must be.

Until spotted flycatchers and other summer visitors depart these shores in the autumn, we can all revel in their beauty and fascinating lives, yet the fragility of the environment means we should never take them for granted.