Intelligence Or Sentience

Is a gradation of moral obligation justified?

If intelligence, how do we define it? Is a honey bee’s dance any less a form of intelligence than our own, or a bird’s migration skills or song any different  in kind from our mastery of language?

Why should one be intelligence and  another described as instinct?

 
If sentience, how do we know how much pain and variety of emotion is felt  by species with which we have little ability to communicate or interpret their behaviour or mere presentation? And if plant  matter reacts to stimulation, may that be evidence of sentience?

We are facing the possibility of mass extinction or near extinction. If this  appears to be inexorably the case, does this change our priorities? Should  we attempt to preferentially save some species or individuals with particular  characteristics of their species, whether for hardiness and possibly less of a  certain kind of sentience, or for intelligence as another form of adaptability?  How about for sociability, empathy, for vegetarian diet, or ecological non  disruption?

 
Is life worth saving anyway? Are the disruptions of physical atoms in a  “lifeless” multiverse any less or more matters of pain and pleasure than those in central nervous systems. Is intelligence of worth beyond a survival  mechanism or a curiosity for other intelligences?

 
Can these questions be addressed by “the man in the street” or  the woman  in labour as well as it can by philosophers?  (I think they can, regardless of  the immense difficulty.)