The World Birding Center (WBC) parks hold events throughout the year. Most of them have weekly repeating events with special events thrown in at least once a month. Estero Llano Grande and Bentsen State Park are two very active parks, along with Quinta Mazatlan and others.
There are nine parks in the system spread throughout the Rio Grande Valley, so you should be able to find one close to you to visit. Or make it a point to visit each one this year. They each have something different to offer.