Seasons of Wildlife


Spring brings migrating songbirds traveling from southern latitudes which stop over at the refuge to refuel using the rich resources that the refuge offers. Late April to early May is when peak migration occurs and when visitors are likely to see the most species. Waterfowl can still be seen this time of year as they make their way north to their more temperate breeding grounds. 


Summer weather brings warm temperatures that cause coldblooded reptiles to come out of hibernation. Visitors are likely to see lizards including spiny lizards and side-blotched lizards. Less common reptile species include diamondback rattlesnakes, chuckwallas, California kingsnakes, and desert iguanas. Summer is also nesting season for songbird species such as the Bell’s vireo, summer tanager, yellow-billed cuckoo, and southwestern willow flycatcher. 


Fall begins the arrival of the migratory waterfowl season when goldeneyes, scaup, mergansers, and wigeons come to feed in the lake portion of the refuge. Migratory songbirds also return as they travel back to the southern latitudes for winter. 


Winter is peak season for waterfowl where large rafts of diving ducks and several species of grebes can be seen from the headquarters trails. Other species of interest are great blue heron and great egret, which can be seen feeding in the shallow water by the shoreline. 

Featured Species

Bill Williams River National Wildlife Refuge is home to many species of birds, fish, reptiles, and mammals. When  visiting the Refuge Headquarters Trail, you may see a verdin, Abert‘s towhee, or yellow-rumped warbler flying from limb to limb. You can also encounter spiny lizards and side blotched lizards sunning themselves and doing pushups on the paved portion of the trail.  

On an early morning paddle up the river delta a you will pass large rafts of migratory waterfowl in the fall and winter. The lucky spring time visitor may hear “kak-kak-kak,” coming from the cattails. This is the call of one of the refuge’s endangered marsh bird species, the Yuma Ridgway’s rail. Common yellow-throats and marsh wrens can also be heard calling in the reeds. The lake portion of the refuge is the historic range of the endangered razorback sucker and bonytail chub. 

A drive down the auto tour route on Planet Ranch Road offers the opportunity to see diamondback rattlesnakes, desert bighorn sheep, red-tailed hawks, and the occasional squadron of javelinas. A walk through the floodplain forest on the eastern portion of the refuge allows visitors to see areas of nesting habitat that were historically used by the endangered southwestern willow flycatcher and the threatened yellow-billed cuckoo. You are likely to hear the call of Bell’s vireos and ash-throated flycatchers.