Territorial behavior of the migratory Lined Seedeater during the breeding season

Abstract

Most bird species will defend a territory during the breeding period to assure the availability of resources for their reproductive success. Migratory birds abdicate their territory ownership during the non-breeding period, posing a challenge for the following breeding season. Here we investigated the territorial behavior of male Lined Seedeaters Sporophila lineola, an intra-tropical migrant, during the breeding season (December–May) 2018/2019 in south-eastern Brazil. The Lined Seedeater is a sexually color-dimorphic species that inhabits open areas and feeds on seeds. We followed 18 color-banded individuals, during the period in which they had an active nest. For each individual, we recorded the locations in which they exhibited any potential territorial behavior, with the aid of a handheld GPS. We then estimated the size and shape of the territories using a Kernel Density Estimator. The breeding territories had on average 0.59 ± 0.24 ha, ranging from 0.21 to 0.91 ha in area. Males exhibited agonistic behavior whenever another male intrudes on their territories, especially if in the vicinity of their nests. Our observations indicate that male Lined Seedeaters defend small territories of exclusive use during the breeding season, but forage over a wider home range shared with other conspecifics. Therefore, Lined Seedeaters and other members of Sporophila seem to exhibit home ranges that are much larger than their breeding territories. Empirical studies are needed to understand the influence of territory size and quality on reproductive fitness. © 2021, Sociedade Brasileira de Ornitologia.