If the cuckoo, the swallow, and the nightjar be pre-eminently the birds
of Summer (though, truly, the swift, the flycatcher, and the corncrake
have as good a title) the rear-guard of Spring may be said to be the
house-martin, the cushat, and the turtle. Even the delaying wheatear,
or the still later butcher-bird may have come, and yet _Sweep-Sweep_
may not have been heard about the eaves of old houses or under and over
the ruined clay of last year’s nests; the cushat’s voice may not have
become habitual in the greening woods; and the tireless wings of the
turtle may not have been seen clipping the invisible pathways between
us and the horizons of the south. But, when these come, we know that
Spring has traversed the whole country, and is now standing ankle-deep
in thrift and moondaisies in the last rocky places fronting the north
sea. No one doubts that summer is round the corner when the flycatcher
hawks the happy hunting-grounds of the apple-blossom, when the swift
wheels over the spire of the village church, and when the wild-dove is
come again. The first call of the cuckoo unloosened the secret gates.
We are across the frontier in that first gloaming when we hear
“The clamour musical of culver wings
Beating the soft air of the dewy dusk.”