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Are you really seeing Grey Ducks?

By pscofield May 2, 2013
Grey Duck1

Some people have commented to us “Why do you query our records of grey duck? The’re common aren’t they?” Well unfortunately they are not. Indeed due to introgressive hybridization with Mallards they may well become the next extinct species in New Zealand.

 We challenge all using eBird to try a useful little key with ducks you suspect may be Grey Ducks to see if they really are. In doing so you will help us understand what is going on with Grey Ducks in New Zealand.

Using the key below if your duck scores more than 7 it is almost certainly a hybrid, I’m afraid. Why not put the hybrid index score in the comments column for your observation?

A Pair of Grey Duck in Australia showing features of pure birds. A well marked face. Distinctive pale edged feathers and dark bills.

A Pair of Grey Duck in Australia showing features of pure birds. A well marked face. Distinctive pale edged feathers and dark bills.

 

 

Characteristic Species Assessment Value (The index gives a score of 0 for the purest Grey Duck and 35 for the purest Mallard)
       
Face striping      
  Grey Duck Two clear black stripes on a cream background 0-1
  Hybrid Obscured face stripes 2-3
  Mallard No face stripe to a thin black eye stripe in the female 4-5
       
Speculum border – anterior      
Grey Duck No white bar 0-1
Hybrid Thin white bar (2 mm) 2-3
Mallard Broad white bar (5 mm) 4-5
 
Speculum border – posterior      
Grey Duck Faint white line 0-1
Hybrid Thin white bar (2 mm) 2-3
Mallard Broad white bar (5 mm) 4-5
 
Bill      
Grey Duck Slate gray 0-1
Hybrid Gray-yellow 2-3
Mallard Yellow-orange 4-5
 
Nape      
Grey Duck Cream 0-1
Hybrid Creamy brown 2-3
Mallard Dark brown in female or eclipse male, varying from a dark green to a purple-green in the breeding plumage male 4-5
 
Tail      
Grey Duck Slate gray 0-1
Hybrid Gray-brown 2-3
Mallard Creamy brown in female or eclipse male, varying from a dark green to a purple-green in the breeding male 4-5
       
Leg      
Grey Duck Gray-brown 0-1
Hybrid Gray-yellow 2-3
Mallard Yellow-orange 4-5

 

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