Dating from around 1910, these are superbly carved. 
 
The stone itself is beautiful and unusual. It has a look and feel of Serpentine and is about a 5 on the Mohs hardness scale, similar to marble. (It's harder than soapstone, softer than Jade)
 
Each bird is 19cm tall to the tip of the crested head. One has had a professional repair where the tail has broken at some point (see last image which has been lightened to try and highlight it), which is not overly noticeable otherwise both are in excellent condition.