THE ZOOLOGIST 



No. 828.— June. 1910. 



THE MECHANISM OF PLUMAGE IN WATER BIRDS. 

 By Frederick J. Stubbs. 



Most observers are familiar with the power of certain birds 

 to alter the degree of their submergence in the water. It is 

 many years since the question was first discussed — by Atkinson 

 and Slaney in the second volume of ' The Zoologist,' and by 

 Beverley Morris in the first volume of his ' Naturalist.' Since 

 then other writers have published their views, without adding 

 anything to our knowledge, and the mystery is as deep to-day as 

 it was sixty years ago ; so no apology seems necessary for this 

 further attempt to solve the puzzle. 



At times the Moorhen — as I have myself frequently observed 

 — and almost certainly the Grebes, hold themselves beneath 

 water by grasping the stems of aquatic plants. It has been 

 denied that the Grebe has the power to so use its toes, but I have 

 several times seen this bird disappear from sight, and remain 

 hidden, under circumstances leaving no room for doubt that the 

 bird was keeping itself beneath the surface by clinging to the 

 vegetation, as a Moorhen will do. Before we state that a Grebe 

 cannot use its toes for grasping, we must consider the structure 

 of a bird's foot, and the way it is used in the case of the Moor- 

 hen and other birds. Owing to the form of the joint between 

 the proximal phalanges and the tarso-metatarsus, the outer 

 digits, when the foot is closed, press in laterally towards the 

 Zool. 4th ser. vol. XIV., June, 1910. r 



