THE SAND MARTIN 85 
and the eaves or windows of a certain house are peculiarly well 
adapted for sheltering nests; so a number of Window Martins, 
not having taken counsel together, but guided each by independent 
choice, find themselves established sometimes so close together 
that their nests have party walls, like the houses inastreet. They 
accordingly make acquaintances, and are sociable to a limited 
extent. But Sand Martins go beyond this, they are comrades 
banded together by municipal laws, which no doubt they under- 
stand and obey, inhabiting dwellings which constitute a joint settle- 
ment, returning without fail to the familiar haunt after every 
annual migration, or if they desert a station, leaving no stragglers 
behind, and pitching their camp anew in some locality which 
common consent has pronounced to be an eligible one. They are 
not, however, exclusive in their fraternization; as they hunt in 
society with their relatives the Swifts and Swallows, and even 
accompany them in distant flights. I have repeatedly observed 
Sand Martins flying about with others of the same tribe many miles 
away from their homes. They may readily be distinguished, as | 
have stated before, by their dingy mouse-coloured hue, smaller 
size, and less forked tails. I have never had an opportunity of 
watching a colony engaged in their mining operations at the busy 
period of their year, that of nidification ; but from the description 
by Professor Rennie (Bird Architecture) and that by Mr. R. D. 
Duncan, quoted by Macgillivray, the sight must be most interesting. 
The task of the older birds must be a light one; not so, however, 
that of the younger members of the flock. The former have neither 
walls nor roofs to repair ; the holes which served them as nests the 
previous year afford the same accommodation as before. All that 
is needed is, that the remains of the old nest should either be re- 
moved or receive the addition of a few straws and feathers to protect 
the eggs and young from direct contact with the cold sand ; their 
labours then are over. But the new colonists have a toilsome work 
to perform before they can enjoy the gratification of bringing up 
a family. The settlement is fixed probably in the perpendicular 
face of a bank of sand, gravel, or clay, at an elevation from the 
ground which varies from a few to a great many feet. Their claws 
are Sharp and well adapted for clinging, the beak short, rigid, and 
pointed, no less well suited for excavating. Grasping the perpendi- 
cular surface of the bank with their claws, and steadying themselves 
by means of their tails, they commence operations by pricking a small 
hole with their bills. This hole they gradually enlarge by moving 
round and round, and edging off the sand with the side of their 
bills, which they keep shut. Their progress is slow at first, but 
after they have made room to stand on the excavation, they proceed 
rapidly, still working with their bills, and carefully pushing out the 
loosened sand with their feet. At one time the male, at another 
the female, is the excavator. When their burrowing is impeded 
