Canaries being prepared for breeding should be in the peak of condition. This applies equally to the feet and legs as it does to the constitution of the bird. My practice is to supply a selection of grits throughout the year, with an added calcium supply in preparation for the forthcoming egg laying cycle. This means I need to keep a watchful eye on the birds toe nails, as they can grow quite quickly, if left unchecked. Long nails may be harmful to the birds if they get entangled on thin perching or aviary wires etc, and can result in damaged toes if they become entangled in nesting material. Similarly, eggs can be punctured, or matings may be unsuccessful.
Introducing birds to their flight cages provides an ideal opportunity to check the nails.
Using a training cage, assess the length of each birds nails. Ideally, they should be no more than a quarter of an inch long. Healthy nails are slightly curved, and without twists or kinks. Over long nails grow in circles, turning back underneath the perch, when the bird is resting.
Mostly, it is just the hind claw and the middle front facing claw which will need trimming. Never use scissors. They are difficult to manage, and may slip. Instead, use a small pair of nail clippers, which have a curved pair of jaws, are designed for the job, and which can be easily operated using only one hand.
Hold the extended claw to the light and you will see a single vein running through the centre of the nail. Clip near to this vein, but be careful not to cut it as you do not want the canary to suffer any loss of blood. If an accident happens, a dab of iodine usually works, or cauterise the wound with a lit cigarette in severe cases.