Every specialist group has it own contact person. 
Go to the specific pages for each group to find their details. In common, the groups are supported by  the headquarter of Wetlands International by:

Wetlands International
Tunde Ojei 
Specialist Group Network Development & Support Officer 
P.O Box 471 
6700 AL Wageningen 
The Netherlands 

Email: Tunde.ojei@wetlands.org 
Direct Tel: +31 317 478866 
Fax: +31 317 478850

You can contact Tunde for all common questions relating the groups. For all other question, contact the Head Quarters.