? They normally lay one egg per season, but if something happens to the egg early in the season they can lay another one.

? Only mature adults pairs have long tails, perhaps as a courting attraction. If these break off the birds grow another one.

? They are selective about choosing a nest. They will fight to the death if another bird occupies or fancies "their" nest.

? Unlike land birds, longtails cannot walk because of the position of their legs, and fledglings do not practise flight. Their initial take-off is a one-shot deal.

? Chicks are speckled black and white, adults are pure white with black bars.

? Adults moult once a year and grow new feathers.

? Feathers replace down in precise order: wings first, back and breast next, head last.

? People finding chicks should never feed or give them water but take them directly to the Bermuda Aquarium, Museum and Zoo's rehabilitation facility.

? Clean nests are important to these birds. Chicks sit in the centre and defecate outwards in a circle. Parents regurgitate food directly into the chicks mouths.

? The birds use an oil gland near their tails to preen their feathers to make them waterproof at sea. Dirt on the bird impedes waterproofing.

? During courtship adults birds leave the nest in the afternoon. Otherwise they go out morning, noon and evening to get food for young chicks, and morning and evening for older chicks.

? The birds have a crop (gular pouch) and a stomach. For very young chicks adults swallow the food into the stomach before regurgitating it to make it softer; for older birds they hold the catch in their crops before feeding.

? The official name of the longtail is 'white-tailed tropic bird' ? one of eight or nine sub-species worldwide.

? The longtail is not Bermuda's national bird.

? Chicks indicate to the parent when they are ready to fly, not the other way around. They do this by not eating for at least a few days ahead of departure.

? Fledging is the time between hatching and nest departure.

? The adult wing span is approximately two and a half feet.

? A fully-fledged chick weighs more than an adult bird, which is a survival mechanism.

? The age of a fledgling can be determined by specific measurements and other indicators. Adult birds have no down. Legs grow to a standard measurement.

? The sex of a longtail cannot be determined visually. Short of cutting the bird open, only an extremely experienced ornithologist or someone who has done a lot of work with these birds can determine the sex.

* Bermuda has an estimated one-fifth of the longtail population of this sub-species and this sub-species' largest nesting population in the world. * The adults arrive in good weather and leave in bad.