Alexander was a lifelong, dedicated and gifted birdwatcher, keenly involved in the 20th-century movements for the protection and observation of birds. He and two of his older brothers, Wilfred and Christopher, he took a keen interest in nature. Growing up in a Quaker home devoid of any other forms of entertainment, his interest in birds began at the age of eight, when his older brother Gilbert gave him a book on natural history. In his autobiography he traced the beginnings of this interest in birds to 8.45 am on 25 March 1897, when an uncle pointed out a singing chiffchaff in their garden. It was not until he was 20 that he obtained his first pair of binoculars. He was one of a small group of amateur birdwatchers who developed skills and set new standards for combining the pleasures of birdwatching with the satisfaction of contributing to ornithological science. He made many significant observations, mainly in Britain, but also in India and the United States.
