What it means to "defend animal rights"

We need to
(a) BELIEVE in the social construct of rights

(b) BE ABLE to clearly conceptualize and express the social construct of rights and the rightful inclusion of nonhumans within the scope of that construct's applicability
(c) BE ABLE AND WILLING to consistently live out the practical implications of that social construct (e.g. veganism)

(d) BE ABLE AND WILLING to tease out the long-term implications for each society of the practical implications of that social construct (e.g. abolition of all animal agriculture and exploitative social USES of animals), in ways that are attractive to the broad reach of each society and highly desirable (more desirable than any status quo exploiting animals or any ACTUAL new way of exploiting animals or the POSSIBILITY of any (some) new way appearing in the future that could be used to justify the exploitation of nonhumans.

I'd say that's a very tall order. I'd also say that we are only beginning to achieve the aggregated social maturity as a vegan movement to deal with that whole-cloth, in the aggregate, even though a number of really great books (Lee Hall's included) have appeared to help us individually work through these issues and implications in our individual lives.