Little egret and great egret
These photos show a kotuku (whote heron or great egret - egretta alba) and a little egret (Egretta garzetta). The much larger kotuku is a rare native of New Zealand and uncommon to rare (though a very common bird elswhere in the world, NZ being the southern limit of its range). The little egret is a very rare (in NZ) seasonal migrant to New Zealand from Australia. A small number of these birds make the journey in autumn and return to Australia in the spring.