Bird diversity and abundance at the Hadejia - Nguru Wetlands, Nigeria was studied within an eleven week period in 2011 to determine the effects of wetlands size and type. Thirty two wetlands within the Hadejia - Nguru Wetlands complex were surveyed. The study involved recording birds at predefined wetlands within the Hadejia- Nguru wetlands complex. Point counts were used to survey birds. Bird count was from 06:30h to 11:00h in the morning and 16:00h to 18:00h in the evening. Data collected was explored for normality and Shannon-Wiener index was used to determine the diversity. Bird diversity and abundance determined by counting birds was related to wetlands size and type. A total of 110,162 of 119 bird species were recorded. Bird species richness and diversity varied across wetland types: Marshes had the highest number of bird species compare to Ponds and lakes whereas bird diversity was significantly higher in ponds than lakes but was similar to the diversity of marshes. Wetlands size decreased bird diversity.