XVII. 
NOTES ON BIRDS OBSERVED IN HERTFORDSHIRE DURING THE 
YEAR 1890 AND THE EARLY PART OF 1891. 
By George Hooper, E.Z.S. 
Bead at Watford , 1 §th March , 1891. 
There are few subjects connected with the study of natural 
history more interesting or more incapable of explanation than the 
migration of birds. The moving cause is obvious enough—the 
failure of food or the inclemency of the weather in the locations 
from which they flee. But what the guiding-power is which carries 
even short-winged birds across not only vast tracts of land, but 
considerable arms of the sea, to their destined abode, is a mystery. 
All we know is that year by year, at the same appointed times, the 
same birds seek their appointed places. We can only attribute it 
to the marvellous workings of what we call “ instinct,” implanted 
in their nature. Such birds are usually classed as “migrants.” 
But I think that this term is used in too limited a sense, when 
applied, as it is exclusively, to foreign visitors or to birds which 
being bred here seek foreign lands when winter approaches. 
All birds are more or less migrants. Even the ubiquitous sparrows 
forsake the rickyards and the dwellings of men in the autumn, and 
seek in great flocks the fields of ripened corn. The thrushes which 
swarm on my yew-trees when the berries are ripe were not bred in 
the garden, nor when the crop is devoured will they there remain. 
A few pairs of wood-pigeons pay me an annual visit in March, and 
leave me in October or November. The thrushes, I think, travel 
northward, in company with their congeners, the redwings, to 
feast on the abundant berries of the rowan, the thorn, and the 
bramble. The comparative failure of wild fruits, owing to the 
lengthened frost this year, drove the poor hungry birds back again, 
southward, the mistaken result of blindly following their instincts. 
The weather in the north this winter was many degrees warmer 
than in the south, and the thrushes which reached our southern 
coast perished in vast numbers ; more than 300, I am assured, were 
picked up dead in one garden at Bournemouth. Hooks, as we all 
know, leave their nesting-trees when the season is ended, and seek 
“ fresh fields and pastures new.” Plovers, starlings, and many 
other birds abandon their breeding-stations when the young can fly 
and shift for themselves, and collect in distant quarters in vast 
flocks. These, and indeed all birds, as I have said, are migrants, 
properly so called; that is, they change their place of residence as 
circumstances seem to require. 
Birds which spend only a portion of the year with us, and seek 
foreign climes for the remainder, may, I think, be called emigrants 
or immigrants. In the first category I would place our summer 
birds, the swallow, the nightingale, the cuckoo, and others, which, 
seeking our shores in the spring, acquire what I may call a settle¬ 
ment, having a domicile in the shape of a nest, and bringing up a 
