I’m enjoying very much reading the newly published George Orwell Diaries, also available online here. In addition to politics and fascinating insights into the daily life of the late 1930s such as the price of eggs, there is a remarkable amount on natural history, clearly something Orwell found important and interesting. Although the diaries do not cover his time in the Civil War in Spain, he does write this from Gibraltar in September 1938:

Weather mostly hot & nights sometimes uncomfortably so. Sea variable mostly rather choppy. When no wind fish visible at least 10 feet below surface.
The Barbary Ape is said to be now very rare at Gibraltar & the authorities are trying to exterminate them as they are a nuisance. At a certain season of the year (owing to shortage of food I suppose) they come down from the rock & invade peoples° houses & gardens. They are described as large doglike ape with only a short stump of tail. The same species found on the African coast just opposite.
The breed of goat here is the Maltese, or at any rate is chiefly Maltese. The goat is rather small, & has the top half of its body covered with long & rather shaggy hair which overhangs to about the knees, giving the impression that it has very short legs. Ears are set low and drooping. Most of the goats are hornless, those having horns have ones that curve back so sharply that they lie against the head, & usually continue round in a semi-circle, the point of the horn being beside the eye. Udders are very pendulous & in many cases simply a bag with practically no teats, or teats barely 1/2 inch long. Colours black, white & (especially) reddish brown. Yield said to be about a litre a day. Goats apparently will graze on almost anything, eg. The flock I watched had grazed the wild fennel plants right to the ground.
Breed of donkeys here small, like the English. The conveyance peculiar to the place a little partly closed in carriage like the Indian gharry with the sides taken out.

Photo from Wikipedia by Karyn Sig