Migratory timing, rate, routes and wintering areas of White-crested Elaenia (Elaenia albiceps chilensis), a key seed disperser for Patagonian forest regeneration

Abstract

Migratory animals often play key ecological roles within the communities they visit throughout their annual journeys. As a consequence of the links between biomes mediated by migrants, changes in one biome could affect remote areas in unpredictable ways. Migratory routes and timing of most Neotropical austral migrants, which breed at south temperate latitudes of South America and overwinter closer to or within tropical latitudes of South America, have yet to be described in detail. As a result, our understanding about how these birds provide links between South American biomes is almost non-existent. White-crested Elaenia (Elaenia albiceps chilensis) is a long-distance austral migrant that breeds in the Patagonian Forest biome and overwinters in tropical South America. Because this small flycatcher plays a key role in the regeneration of this ecosystem, our objective was to describe the annual cycle of White-crested elaenias to evaluate the degree of migratory connectivity between breeding and wintering areas and therefore to determine if there are specific biomes of northern South America linked by elaenias to Patagonian forests. Fifteen individuals were successfully tracked throughout a complete migration cycle using miniature light-level geolocators. All individuals resided and moved through the same general regions. During fall (March-April-May), elaenias were located in the Caatinga and the Atlantic Forest biomes, from Rio de Janeiro to the region near Salvador da Bahia, Brazil. During winter (June-July-Aug.), birds were located further inland, within the Cerrado biome. Birds used three different routes during fall migration. Our results indicate that some individuals use a direct route, flying between 500–600 km/day, crossing desert and grasslands, while others took a detour, flying 100–200 km/day through forested areas with refueling opportunities. All birds used the Yunga forest during spring migration, with ten out of 15 individuals showing a clear counterclockwise loop trajectories throughout their annual cycle. None of the elaenias passed through Amazonia, traveled to western South America or crossed the Equator. Eleanias exhibited a high migratory connectivity between breeding area in Patagonian Forests and winter areas, Atlantic Forest and Cerrado. Our results suggest that Patagonian Forests could be strongly impacted by changes in those biomes or in the Yungas.

Breeding latitude predicts timing but not rate of spring migration in a widespread migratory bird in South America

“…However, Fork‐tailed Flycatchers from across different sites migrated at a similar pace. Notably, the spring migration rates exhibited by austral migrant Fork‐tailed Flycatchers (i.e., ~134 km/day) are similar to those of another austral migrant flycatcher, the White‐crested Elaenia, which migrates on average between 121 and 261 km/day (Bravo et al, ).…”

“…Bird migration across the New World is ubiquitous, from high Arctic tundra to Patagonia, and research on the mechanisms underpinning avian migratory patterns in the New World and beyond continues to be a rapidly growing area of inquiry. Such studies have shown that the timing and pace of migration and the location of migratory routes can vary widely not only between species, but also between populations within a species (e.g., Sylvia warblers, Fransson, ; Collared flycatchers, Ficedula albicollis , Briedis et al, ; Northern wheatears, Oenanthe oenanthe , Bairlein et al, ; Wood thrushes, Hylocichla mustelina , Stanley, MacPherson, Fraser, McKinnon, & Stutchbury, ; White‐crested elaenias, Elaenia albiceps , Bravo, Cueto, & Gorosito, ). Understanding the causes of such variation is vital for developing a basic understanding of the evolution and regulation of migration, as well as for evaluating the fitness consequences of employing a given migratory strategy, since processes that occur in one season can influence the survival and reproduction of an individual in subsequent seasons (i.e., through carryover effects, reviewed by Harrison, Blount, Inger, Norris, & Bearhop, ).…”

Demography of the Neotropical austral migrant Elaenia albiceps chilensis (Tyrannidae) on its breeding grounds: climate and food offer effects

“…Th e White-crested Elaenia (Elaenia albiceps chilensis) is the most abundant Neotropical austral migrant passerine at the Patagonian forest (Grigera et al 1994, Ippi et al 2009. Th is tyrant fl ycatcher arrives up to mid-October to breed and start its migration to the tropics between mid-February and March (Fitzpatrick 2004, Bravo et al 2017. It is a frugivorous-insectivorous species with an important role as the main disperser of seed of endemic plants of the Patagonian forest (Armesto et al 1987, Amico & Aizen 2005 and as a controller of herbivorous insects of Nothofagus trees (Mazia et al 2009).…”

“…It is a frugivorous-insectivorous species with an important role as the main disperser of seed of endemic plants of the Patagonian forest (Armesto et al 1987, Amico & Aizen 2005 and as a controller of herbivorous insects of Nothofagus trees (Mazia et al 2009). Th ere are studies of White-crested Elaenia abundance (Brown et al 2007), diet (Grigera 1982, Brown et al 2007, foraging behavior (Chust et al 2012, Cueto et al 2016a, functional role (Mazia et al 2009, Cavallero et al 2013, and migration routes (Marini & Cavalcanti 1990, Capllonch et al 2011, Cueto et al 2016b, Bravo et al 2017, but its survival has never been studied, as well as the relationship between its demographic parameters with environmental factors.…”

“…Th is could be due to events of lower reproductive success (as in the fi rst studied season), or higher mortality during the nonbreeding period. As White-crested Elaenia present high migratory connectivity between their non-breeding and breeding areas (Bravo et al 2017), the decrease in their captured rate could also be related with environmental variations at their wintering sites on the Brazilian Cerrado and Atlantic Forest (for example, see Wilson et al 2011).…”