Describe before you compare
Write the features you noticed while the encounter is fresh. Then compare candidate species against that description. Check whether the suggestion fits the country or region and the setting. A match on one feature should not erase a clear mismatch on another.
- Overall size and body proportions
- Bill, tail and wing shape
- Movement and feeding behavior
- Habitat and position in the vegetation
- Repeated sound pattern, if heard
Use a suggestion as the beginning of a check
Warbla can suggest birds from a photo or live sound on the iPhone and filter candidates by country or region. Open the field-guide entry and compare the features that are actually visible or audible in your encounter. Do not add a species merely because it was the top suggestion.
If two candidates remain plausible, keep both in your notes with the reason you could not distinguish them. Review the observation later without approaching the bird for a better view. The ABA's ethics code puts restraint around observation and photography; a name is never worth disturbing a nest or entering restricted habitat.