Its a duck, a green wing teal I believe. Birds have a number of predators, small and medium mammals, other birds, reptiles. Could be a hawk or owl, or a cat or fox or raccoon. Squirrels even will raid nests I believe.

I cannot dismiss early stage gummosis by looking at the picture above. I think a local expert should look at the tree. If this appeared on my roses I would say it is the work of a sawfly but on citrus? In the meantime I would isolate the tree if potted, treat the wounds and the soil with copper and if more of it appeared I would cut off the affected canes making sure the wood exposed looks nice and healthy. To investigate further ones needs to look at the state of the foot below the soil so a little digging may be in order. The fungal disease called 'Citrus gummosis' starts at the root and foot but there are also other types of gummosis. Also take a look at this, paying attention to 'citrus gummosis' and 'Rio Grande gummosis' https://cals.arizona.edu/extension/ornamentalhort/plantprotect/citrusdisease.pdf

Thanks a lot Esther - you sure know a lot and willing to share that knowledge - very much appreciate it!

Hi All Thanks a lot for the IDs - much appreciate your sharing of your knowledge! Like Esther, I too thought it was a Towhee but then wasn't sure since I didn't see any white on him, he was much darker brown, and had a sharper beak. He was quite far away (used 400mm lens). Thanks again Shyamala