A NATURALIST'S CALENDAR.

Otago Witness, Issue 2603, 3 February 1904, Page 10

A NATURALIST'S CALENDAR.

By G. M. Thomson, F.L.S. FEBRUARY.

To write a. calendar which is even approximately accurate as a record of natural events is somewhat difficult anywhere, and is particularlj r so in a country stretching through such a range of latitude as New Zealand does. Some districts are months rather than weeks ;n advance of others as far as vegetation is concerned, so these votes must be taken to apply only to Dunedin and its immediate neighbourhood in reference to this aspect of Nature. But while this diversity in point of time is true for the vegetable kingdom, we find that another seasonal change marked by the migration of birds is much more uniform for the whole country. This subject, so far as the New Zealand group of islands is concerned, is not very much known, and it is one which might well enlist the assistance of those interested in bird-life. In Britain, where the observers number thousands, the dates and conditions of migrations of bird-life are beginning to be well understood, but in this colony, where there are so few qualified observers, the wonder is that so much good work has been accompli*hed as the records show to be the case. Lighthouses are most favourable vantage points for watching the migrations of birds, and some of those on the New Zealand coasts are particularly well suited for the work. There have been several good observers among the lightkeepers, and in an occupation which must often prove very tryine from its monotony the interest which the reoording of natural phenomena displays must often prove a valuable thing to the possessor. Frequently when birds are arriving from an oversea flight they are caught or seen in the neighbourhood of a lighthouse in a more or less exhausted condition, so that it is usually more easy to fix the date of arrival of a species than its departure, unless the latter takes place in flocks, when they gather together in some conspicuous place for a few days before taking their final flight.

The cuckoos are the most familiar examples of migratory birds, the long-tailed species coming to these islands from its winter home in the Pacific Islands, while the shining cuckoo migrates between New Zealand and Australia-, or perhaps New Guinea. The long-tailed cuckoo usually 'leaves New Zealand" for its northern habitat during this month of February, being very seldom heard later ; while the shining cuckoo is considerably earlier. But while these dates are fairly accurate for the main tides of migration, stragglers are found much later, and I have a note mads on April 5 (1896) of watching one in a pear tree just in front of one of the windows. We saw the bird at close range, and were able to observe it for some time as it moved about among the foliage. Besides the cuckoos there are numerous kinds, principally of shore birds — plovers, sandpipers, snipes, godwit, curlews, and allied forms, — which are probably all migratory. They differ, however, from the former in one important particular — namely, that whereas the cuckoos come here to breed and to spend their summer, the others mostly visit these shores to avoid the northern winter, returning — in some wellauthenticated cases — to the lakes and tundras of Siberia and other far north regions to spend their summer there.

Dwellers in town have not much chance of watching and recording the habits of birds, but those who live in country districts and by the seaside have frequent opportunity, and if their observation is aided by a good field-glass it is wonderful what an amount of knowledge they can acquire about their feathered visitors. ■

February is a month of ripening fruits and seeds, and although in many instances this phase of plant-life seems to have little to attract the naturalist, yet to the eye that looks below the surface of things there is as much to wonder at and admire in autumn as in any other season of the year. Perhaps at no other time is the fact of the struggle for existence among plants brought home more forcibly to the observant mind. The main object of existence among all organisms seems to be to reproduce their kind, and this is more conspicuously manifested and more easily observed among plants than among animals. Those who study human statistics know that the death rate among infants is high, and that, the rate diminishes as the adult stage is approached, a very considerable proportion of children born into the world growing to maturity. But on looking into the conditions of life among the lower animals and plants it is found that it is not the few which die and the many which survive, but that a very minute pvopoitiom alone of the progeny survives to maturity, while an enormously vast majority die in the course of their individual development. Figures are not available for plants ; they have probably been worked out by some of those patient Teutonic observers who mine and fossick in all sorts of dust heaps, only I cannot lay my hands on them at present. Yet one has only to consider any fruiting plant to notice what an enormous discrepancy there is between the seeds produced and the resulting mature plants. To anyone who has time for such an experiment — and it fl ill be found a more instructive exercise than worrying out the inane puzzles which are so comm-

only propounded in magazines and other ephemeral literature — I recommend the following : — Take a foxglove plant which is neariy past flowering, and picking a ripe capsule from near the lower end of the raceme, count the contained seeds. Then multiply this number by the number of capsules borne by the plant, and the resulting figures will be found to be very large. If all the foxglove seeds ripening in and about Dunedin during this month of February were to produce mature plants it is certain there would be no room for any other kind of vegetation. Yet the foxglove is not one of our commonest plants. But there is no reason to believe that the number of these plants which will be found a year hence will be much larger than it is now. The inference, then, is that the vast majority of the seeds now produced are doomed to destruction. It was from a contemplation of facts like this that Darwin was led to his views on the " struggle for existence " and the " survival of the fittest."

The number of plants which produce seeds in vessels which open is very great. It includes nearly all the family to which the foxglove belongs, such as frogsmouth, veronica, etc., also such familiar plants as poppies, mignonette, wallflower, chickweed, and countless others. As the seeds ripen they drop ail round the parent plant, so that the struggle for bare life is most severe among closely related individuals of the same species. Most plants which do this are either annuals or -biennials. As a rule they have feeble powers of dispersion. Just imagine a tradesman, say a grocer, with half a dozen sons, establishing them all as grocery immediately round his own shop ! One of the lot might survive, or even two might succeed in a fashion, but the majority would succumb. Yet a poppy will drop 10.000 seeds round its dying stem, and if all germinate there will necessarily be a very hi<^i death rate before the few survivors reach the flowering stage.

Frequently plants with dry seed vessels are provided with devices for scattering the seeds. Clematis and anemone and many composites like thistles and dandelions develop some sort of feathery appendage either on the seeds or on the fruit, and this serves to distribute them by the agency of the wind. Others flatten out their fruits or seeds for the same purpose, such as the Norway maple, honesty, and the New Zealand flax. Others, again, throw away their seeds to some distance, a fact familiar to the most unobservant in gorse and broom, whose pods crack with a little report on still, hot autumn days.

Then there is the vast class of plants with succulent fruits, which are so developed that they may be picked or swallowed by birds and so distributed. Large fruits of this kind are not swallowed, of course, but fruit-growers know that when a thrush or a blackbird is disturbed at the morning's meal on the peaches or apricots it will sometimes thrust its beak into a fruit and fly away to some sequestered spot to pick the succulent part off the stone. Small fruits, and especially berries, with several seeds in them are swallowed holus-bolus*, and this accounts for the increase of elderberries in the Town Belt, as well as of fuchsias, hina-hina, and many others of the same type. By the introduction of fruit-eating birds into the country the spread of such plants has been greatly increased.

Lastly there are a few plants whose fruits or seeds catch on to passing animals, and are thus carried about. These are necessarily few in a country which possesses no indigenous terrestrial mammals. But an examination of a common piri-piri (vulg. bid-a-bid) will show that it is singularly well adapted for this mode of distribution, and that the barbs which are so troublesome to the picnicker are exquisitely formed little anchors of the most perfect construction.

February, then, is a month of much interest to the naturalist, for all the pulses of life are still flowing strongly, and Nature is full of the beauty and vigour of the warm season. Dunedin, 30th January, 1904.