the Secretary of the Interior is authorized and directed,
from time to time, having due regard to the zones of temperature
and to the distribution, abundance, economic value, breeding
habits, and times and lines of migratory flight of such birds, to
determine when, to what extent, if at all, and by what means, it is
compatible with the terms of the conventions to allow hunting,
taking, capture, killing, possession, sale, purchase, shipment,
transportation, carriage, or export of any such bird, or any part,
nest, or egg thereof, and to adopt suitable regulations permitting
and governing the same, in accordance with such determinations,
which regulations shall become effective when approved by the
President.