1) that Nightjars preferred areas with small scattered trees, their nest scrapes usually being found near a small bushy birch tree. 2) that the nest scrape was usually on bare ground and with other scattered bare ground patches amongst the heather nearby. Nightjars were once frequent summer breeding visitors to the Forest. Now much declined, they would be hard put to find an area of suitable ground as described above in the Forest. Special attention to Nightjar needs at Minsmere is thought to have trebled the numbers breeding on the reserve. The Woodlark, another bird of heathland, has been of only sporadic occurrence in the Forest. It was listed by Doubleday (Christy, 1890) but not by Buxton (1911). It did, however, have a brief period of breeding in the Forest in the 1940s and 1950s. Typically it was reported breeding from Woodford Golf Course. The course still has vestiges of a grass-heath flora. The Woodlark prefers to forage on very open bare ground presumably conditions (plus I imagine a lack of human disturbance during wartime) met with on the golf course. Other heathland birds formerly found as uncommon and irregular breeding species in the Forest include the Stonechat and Whinchat. Doubleday reported the Stonechat breeding in the Forest in the 19th century. It no longer does so. Its nearest breeding site is in rough grassland at Rainham Marsh. The presence of the Yellow Wagtail in the Forest in the 19th century may have had a lot to do with its association with the Forest cattle. Percy Lindley wrote in 1886:- 'On the lower moister ground especially near the pond sides .... is the Yellow Wagtail.... (it) loves the society of cattle and follows them when grazing, to seize the insects which they disturb from the grass.' It may well have declined with the numbers of cattle and perhaps also increasing human disturbance of its breeding areas. A factor common to many birds found in the Forest is that they are summer visitors, and many of the birds fly enormous distances from their wintering quarters in Africa to nest in the northern temperate regions. External factors thus influence the arrival or non-arrival of many birds. Many species have apparently been affected by prolonged drought in the south Saharan Sahel region. Other external factors include excessive shooting, trapping and habitat destruction and also local pollution in many countries. The Red-backed Shrike once nesting in numbers in the Forest (17 pairs in 1945) now no longer does so and is indeed virtually extinct as a breeding species in Britain. The last few breeding pairs were found mainly on southern heaths. A succession of cool, insect-impoverished summers may have contributed to the contraction in range over western Europe: Britain is only on the edge of this species' range. Other factors may, however, be involved, perhaps in the same way that the Collared Dove has been able to expand and colonise vast new areas in a short period of time, including Britain since 1957, so some formerly common species contract in range. Redpolls, too, have increased greatly in numbers in the Forest, perhaps associated with the increase in the amount of Birch seed now available to this species. Birch is now a very common tree, having invaded many of the heathy plains in the absence of grazing pressure. A feature of the Forest is the large numbers of visitors, particularly on summer weekends; perhaps human disturbance may influence the continued absence of some formerly common species. Some birds may nest in the Forest, but largely forage outside it. An example is the Rook nesting in the Lower Forest. This species has declined greatly in Essex. There was a huge rookery with over four hundred nests in Wanstead Park at the turn of the century. Rooks have apparently been declining, not so much due to the loss of elms through Dutch Elm Disease as nesting sites, but probably the magnitude of the destruction of permanent pasture in favour of cereal crops in recent decades, where Rooks would forage. The Rooks at Wanstead declined almost certainly as a result of the increasing urbanisation around the southern Forest. The decline in game-keeping practices in areas outside the Forest, particularly in the case of birds of prey, must have had some influence on numbers of these species in the 19th century and the early years of the 20th century, although paradoxically the Epping Forest Bird Protection League founded by E. N. Buxton in 1895, specifically advocated the protection of the Magpie, but named the Sparrowhawk as not requiring protection. I imagine despite inroads by gamekeepers this hawk was then not uncommon. Magpies were very uncommon in the Epping Forest area in the early 20th century. For some reason now they are abundant and changes in their behaviour patterns have allowed them to successfully invade many urban gardens in their search for food, in particular the nestlings of song birds in the spring. Another profound influence on the avifauna of south-west Essex has been the construction of large bodies of water in one form or another. There were few large areas of open water in this part of Essex before 1853 when the first of the Lea Valley reservoirs was constructed. The Wanstead Park Basin 158