Korsgaard & Uexküll on animals

You can see from this description that incentives and principles exist in natural pairs. The fact that an animal has certain instincts explains why it is subject to the associated incentives. In this sense the animal's instincts play a double role in the account of its actions. They both explain why the animal is subject to certain incentives in the first place, and what it does in response to those incentives once they are present.

K supra, U infra (text from A Stroll Through the Worlds of Animals and Men, image from Theoretical Biology):

Here again, we have an interrupted chain of functional cycles, not a goal action.  The perceptual cue of peeping normally comes indirectly from an enemy who is attacking the chick.  According to plan, this sensory cue is extinguished by the effector cue of beak thrusts, which chase the foe away.  The struggling, but not-peeping chick is not a sensory cue that would release a specific activity. It would be quite incongruous if it were, too, as the mother hen is in no position to loosen a noose.

The image ends up not fitting well with the layout and so a link to it has been substituted.