Parks are included: 
Prek Toal Ecotourism Site was established in 1999 and located in Battambang Province, Northwest of Cambodia. Prek Toal is a floating village with a bird sanctuary. Paddling through the floating village is being offered to see crocodile and fish rising farms and many more interesting things. 
Ang Trapeang Thmor is located in Banteay Meanchey Province in the Northwest of Cambodia. It is about 100km from Siem Reap Town. Ang Trapeang Thmor is a unique wetland ecosystem giving home to over 200 bird species including the endangered Sarus Crane. The population of the Sarus Crane species in this area rose constantly within the last years to a number of more than 300 birds today. 18 of the existing species in Ang Trapeang Thmor are being classified as globally or near globally threatened. 
The Cambodian government has established six protected areas to safeguard the Bengal Florican (Houbaropsis bengalensis), a large grassland bird that is Critically Endangered with extinction, due to rapid habitat loss and hunting. The total protected area is more than 310km2, within the Tonle Sap grasslands. These areas are called Bengal Florican Conservation Areas (BFCAs). These BFCAs benefit both wildlife and local communities, whilst leaving room for intensive development activities elsewhere. 
Tmatboey is situated in Kulen Promtep Wildlife Sanctuary in the North of Cambodia which is the largest remaining area of dry deciduous forest in South East Asia. Tmatboey and its dry forest harbor two critically endangered Ibis species: the Giant Ibis and the White-shouldered Ibis. 
Kratie and its Mekong River is home to a group of rare sweet water Irrawaddy dolphins. The river also has hundreds of green islands, and circling water. Kratie town is sleepy but picturesque with sandbars and big islands out front and bends in the river. Unlike in many towns around Cambodia, the war years were fairly kind to the French architecture and the roads, at least in the town itself. 
After Cambodia, if time permits, you can enter Vietnam by land from Kratie and continue your wildlife journey with Nam Cat Tien National park or Tram Chim National Park before flying home  from Ho Chi Minh City. 
Best time to go:
Dry season from December to April is the best time to take this wildlife tour. Both of Cambodia and South Vietnam share the same weather condition. You can have good weather for both of the countries.