ONE of the chief joys of the English outdoors is the delightful variety of its native birds. It is fitting, therefore, that the bulk of this series of talks by Sir William Beach Thomas , the well-known writer on Nature subjects, and author of 'The English Year,' should deal chiefly with the songs and habits of the birds. In the last two talks, however, he will travel to the four-footed animals by way of that strange hybrid, the bat.