(3) _Size and temperament._ Medium-sized pigeons are most desirable and birds should be mated to attain this uniform size. Birds being mated to breed stock for pigeon communication should be calm and easy going, not high-strung. Nervous or excitable birds should never be mated. 40. Line Breeding The aim of breeding from pigeons of the same or closely related parentage is to reproduce the qualities of the old birds in their young, amplifying the good qualities and minimizing the bad. Line breeding requires the services of an experienced pigeoneer. Only champions which are physically perfect should be mated. Except for line breeding, inbreeding should not be practiced. 41. Nests _a._ Bowl PG-75 is an expendable item made of pressed wood pulp and is used as a nesting place for pigeons. It is advisable to replace the bowls occasionally to avoid vermin. Cocks display a keen desire to use the same nest compartment each time they are mated or, if moved to a different loft, the nest compartment in the same relative position as the one occupied previously. If not permitted to do this, the cock will fight the occupant of the compartment. Therefore, consult previous breeding records carefully in assigning nest compartments. Hens do not show this trait, but accept a change in compartments and follow their mates. _b._ Keep a supply of tobacco stems for nest material in a rack on the floor of the loft. Allow the pigeons to arrange this material to suit their fancy. Put a handful of sawdust or wood shavings in the nest bowl to prevent breaking of eggs. 42. Control of Breeding The method of control given below is simple, natural, and successful; it requires minimum handling of the birds. [Illustration: _Figure 39. Parent pigeons in nest with youngsters in Bowl PG-75._ TL70208] _a._ TIME. Since best youngsters are obtained when birds are mated during February, March, and April, whenever possible, arrange all breeding for the year during these months. Eggs which should not be hatched should be replaced with EGG PG-50 (glass). _b._ MATING. To begin breeding, place each pair to be mated in its nest, and confine for approximately 1 day. Open one of the nests and allow the pair to leave and return at will. The pair may be considered mated after it returns to the nest several times. Close the nest compartment and proceed in the same manner with the next pair, and so on until each pair is mated. _c._ AFTER MATING. To minimize the danger of birds entering the wrong nest and fighting, open only alternate nest compartments for the first few days after mating. _d._ FOLLOWING SEASON. Any pair producing outstanding youngsters should be mated the same way each year. Mated pairs producing unsatisfactory youngsters should be separated and each pigeon remated. Destroy breeder pigeons which produce unsatisfactory youngsters subsequently. 43. Laying