Do birds emit infra-red radiation?
Short answer
Birds emit infrared.

Background
Objects with a temperature higher than the background emit detectable infrared (IR). Endothermic (warmblooded) animals keep their body temperatures at around 37oC and given the relatively cool temperatures at the earth's surface, endotherms generally emit more IR than the background. Endothermic animals include the mammals and birds, but also some fish. 


Infrared image of a hummingbird. Source: Nature Conservancy.

Note that dinosaurs were probably not ectothermic (coldblooded), but they are believed to have been mesotheroms, that is somewhere in-between ecto- and endothermic (Grady et al., 2014).     

Also note your IR recordings will benefit from lower temperatures and reduced light-pollution from the sun, hence your recordings will be better at night than during daytime.

Reference
- Grady et al., Science (2014); 344(6189): 1268-72