Capsaicin itself is technically 'tasteless' to our own taste buds short of a possible vanilla like flavor that is likely completely overpowered... What we are actually feeling (false taste) when we eat capsaicin containing foods is a 'pain' by our pain receptors in the mouth, capsaicin actually binds to mammalian pain receptors, we just associate that pain with a taste when it's consumed as a food... On the other hand we can note it's clearly a 'pain' perception when it irritates other parts of our bodies like the skin, mucus membranes and sometimes our tail end on the way out of the body even though those areas clearly lack 'taste buds'... This pain reception from capsaicin is true for most mammals...
On the other hand birds pain receptors are mostly indifferent to capsaicin and thus they don't get the 'pain' sensation from contact instead some studies suggest it instead gives them a slight numbing sensation and they might actually taste the subtle vanilla like flavor it does have in some cases... There have even been studies where they have injected birds with capsaicin with nil effect or reaction from the birds body...
