THE BIRDS OF THE LEA VALLEY RESERVOIRS. 195
eleven nests, probably all new with one exception, on July 7th,
1930. The nests were built in privet and elder bushes. In
1932 it was first noted on May 2nd.
The Sedge-Warbler, Acrocephalus schoenobaenus (L.).
It is a summer visitor and has been heard occasionally from
the end of April to the end of June. Although no nest has been
recorded, it is probably a nesting species.
The Wheatear, Oenanthe oenanthe oenanthe (L.).
A regular double passage-migrant in limited numbers.
From one to three individuals have been observed. On the
spring passage it has been seen in the months of March, April
and May, but chiefly in April, the extreme dates for this period
being March 22nd, 1924, and May 15th, 1926. During the
autumn migration it has occurred in August, September and
October. August and September are the most favoured months
of this period, particularly the former, the extreme dates being
August 4th, 1923, and October 21st, 1933. Occasionally birds,
probably the same, are at times seen in the same locality for
two or three weeks. It is probable that some of the birds
recorded refer to the Greenland Wheatear, but none has been
fully identified.
The Swallow, Hirundo rustica rustica L.
It is a summer resident, but is included in this list by reason
of the large gatherings which appear at the time of the autumn
migration and which are, no doubt, attracted by the insect life
of the reservoirs. These concourses generally appear in the
months of August and September. Three were seen on
November 9th, 1926, and one on December 2nd, 1933, these
being late dates.
The Martin, Delichon urbica urbica (L.).
It is included here on account of the numbers, at times very
large, which frequent the reservoirs, particularly during the
autumn migration. Especially large numbers have been observed
in September.
The Sand Martin, Riparia riparia riparia (L.).
Large gatherings frequent the reservoirs from late in July
to early September. These flocks at times run into several
hundreds, are obviously migrational and are attracted by the