102 
MIGRATION AND FLIGHT. 
single line from seaward towards tlie interior. The 
line extended further than the eye could reach, and 
must have consisted of some thousands ; there could 
he no doubt of their being Jays, as several were' 
killed as they passed. But the noise of the guns 
did not occasion the rest to deviate from their line 
of flight: these birds, to all appearance, were then 
coming from the continent. We have before noticed 
the occasional wandering tendency of that steadiest 
of all birds, the barn-door Goose ; in fact, all birds 
seem either at certain seasons, or under certain cir- 
cumstances, to be seized with travelling propensities, 
which they cannot resist. If any of our regularly 
migratory birds are kept in an aviary or cage, when 
the usual time arrives for the departure of the rest 
of their species, these prisoners, without having any 
communication with their companions, will never- 
theless manifest great uneasiness, and often die if 
detained. We have seen this repeatedly in the 
Redstart and Flycatcher, which, though carefully sup- 
plied with the same food on which they have thriven 
for weeks before, and been quiet and apparently satis- 
fied with their lot, will, early in September, begin to 
show great impatience, flying about and striking 
against the bars of the aviary, and usually dying, 
after a few days spent in ineffectual endeavours to 
escape. 
Other facts deserve attention, proving that mere 
climate is by no means, in all cases, the cause of 
these periodical visits. Thus, some birds will, on 
the introduction of a new system of cultivation, 
make their appearance in countries where they were 
never seen before. The Cross-bill ( Loocia curvirostra) 
