T<)20. 



M(WF AT. —Co/on ys of lairds. 



37 



THE (OLOrkS OI^^ BIRDS IN l^ELATION TO THEIR 



HABITS. 



BY C. B. MOFFAT, B.A., M.R.I. A. 



[Address to tlio l^id)lin Naturalists' iMcld Club, Marcli ii, i()2o.| 



The philosophy of bird-coloration has always seemed to 

 me to be rather unsatisfactorily stated by those who have 

 treated of it at any length. I particularly refer to those 

 birds in which either bright tints or interesting patterns 

 have been developed. 



That dull colours are often more or less protective is, I 

 think, pretty generally agreed, though this explanation is 

 often pushed too far. The well known examples of young 

 birds of various species (Plovers, etc.) that run before they 

 can fly are too obvious to call for argument. A few other 

 species readily suggest themselves in which there can be 

 little doubt as to the colour having an important protective 

 value, by reason of the birds' habits being what they are. 

 The Tree-Creeper, a very defenceless little creature, spends 

 practically its whole time performing a series of journeys 

 up the trunks of trees. Its brown colour closely assimilates 

 with that of the bark, and unless it did so the life of the 

 little bird could hardly be worth living. The Nightjar 

 spends the whole day asleep, in spots generally exposed to 

 full sunlight, often on some horizontal branch a few feet 

 (or, perhaps, a few inches) above the ground. If it had 

 any other colour than one closely resembling that of bark 

 or dried heather-stalks it could scarcely escape discovery 

 in such places. The Sand-Martin is, I think, probably 

 another example of true protective colour. While on the 

 wing (as it generally is) its colour can be of no great 

 importance to it, nor does it need a protective hue when 

 sitting in its nest, as that is in a deep burrow. But when 

 it wants to excavate its burrow it has to settle on the side 

 of a sand-cliff and work sedulously there for a considerable 

 time, during which period it must save the bird much 

 disturbance and many dangers to be coloured, as she is, 

 precisely like the sand. I will mention one other bird that 

 may be a case of special protective adaptation, because 



A 



