Recovery Plan for the Northern Spotted Owl - DRAFT

spring. Territories probably are smaller than home ranges, but the exactrelationship between the defended area and the used area is unknown. Bothmembers of a pair vigorously defend the territory through vocalizations andvisual displays. This propensity to defend a territory also is the key to successfulstudy of the species because one can locate the birds through imitation oftheir calls.Spotted owls often form long-term pair bonds (Forsman et al. 1984). Pairbonds do occasionally dissolve, but the reasons for "divorce" are unknown(Franklin and Gutierrez unpubl. data). Nevertheless, several behaviors occurcommonly among spotted owls that serve to illustrate mechanisms that probablyhave evolved to reinforce pair bonds. Calling serves to strengthen pairbonds when it is given in the appropriate context (e.g., nest site selection, preydelivery). Courtship feeding by the male is common during the early part ofthe nesting cycle (Forsman 1976) and may serve as a proximate cue to eitherfood availability or the male's ability to hunt successfully. Finally, physicalcontact, as exemplified by "allopreening" (i.e., mutual preening of feathers),also serves to strengthen pair bonds (Forsman and Wight 1979). Allopreeningis common in other Strix owls (Fitzpatrick 1975, Nero 1980), and is ingrainedso strongly in these birds that captured owls may engage in allopreening withtheir captors (Nero 1980).The nesting cycle begins with the return of the pair from the wintering area tothe nesting area in late winter or early spring (late February to early March).The pair begins to roost together on a more frequent schedule as day lengthincreases. The initiation of laying is contingent upon the physical condition ofthe female, the availability and abundance of prey, and the ability of the maleto capture sufficient prey. The condition of the female probably depends on thefemale's hunting experience and the prey levels within the territory during thewinter and the preceding fall. Once a pair is committed to nesting, the femalelays her clutch of eggs and incubates and broods the young without assistancefrom the male. In fact, during incubation and the first half of the broodingperiod, the female leaves the nest only to defecate, regurgitate pellets, avoidpredation, defend against conspecifics (i.e., other spotted owls), or receive preydelivered by the male. The role of the male is to provide sufficient food to thefemale so that the female need not forage. Once the young have hatched, thejuveniles remain 3 to 5 weeks before leaving the nest. Owlets often leave thenest before they can fly, simply jumping from the nest into the surroundingtree branches or onto the ground. These young birds are fed and tended byone or both of the adults until they disperse in early fall (late September orearly October, see Dispersal). Following dispersal of the young birds, adultbirds begin to expand their home ranges and to roost together less frequently,signaling an end to the annual reproductive cycle.Intra- And Interspecific RelationshipsCompetition: Intraspecific competition is the competition for resources amongmembers of the same species. Territoriality is one expression of intraspecificcompetition. One adaptive advantage of territoriality is that it allows a territoryholder to sequester resources for exclusive use. Because spotted owl prey arepatchy in distribution and variable in abundance (Ward 1990), it is important,if not necessary, for spotted owls to defend territories and use large areas forforaging.Preliminary information on habitat selection gathered by Solis and Gutiirrez(1990) and Sisco (1990) suggest that intersexual (competition between malesand females of the same species) competition may have led to foraging habitatsegregation between males and females. It appears that males and femalesselect forests of different structure, and that the smaller males hunt in denser16