Pied Flycatcher Pied Flycatcher - Arrives mid to late April with the black and white male arriving about a week before the brown and white female. This species appears to prefer a good quality nest box rather than a natural cavity. Commonest species that uses the 350 nest boxes across the reserve. In a good year there can be up to 200 pairs of pied flycatcher, which can produce up to 1000 young. It likes the upland valleys with hillside dominated by sessile oak. One of it's favoured foods is the oak defoliating caterpillar. Since 1985 the British Trust for Ornithology have been ringing the nestbox young with control returns coming in from as far a field as Morocco and south of the Sahara.