mesquite trees are one of the last to leaf out.

The fact both trees are a bit slow ought to be a clue. You've got transplants and it takes at least a full growing season for these things to establish. While we were moist this winter, did you water? Mulch? Even the xeric plants need some help.

Also remember new plants are putting energy in establishing a root system (thankfully) so may be slow. And as just mentioned above, mesquites are slow.....and if in a cold area, can die (but not this winter).

When in doubt about any woody plant do two tests:
1. Feel the limbs. On the side away from the sun, it should be cooler than air temp indicating water movement. If its air temp, chances are it's gone.

2. Flexibility......bend some stems, branchlets, etc. If flexible, not brittle, there's still hope.

I'm in a cold pocket near the river, my fragrant ash, vitex and desert willows are just leafing out.

BTW, my screwbean mesquite just leafed out this past weekend. I live on the west side near the petroglyphs.