Advances and Environmental Conditions of Spring Migration Phenology of American White Pelicans

Abstract

Spring migration phenology of birds has advanced under warming climate. Migration timing of short-distance migrants is believed to be responsive to environmental changes primarily under exogenous control. However, understanding the ecological causes of the advancement in avian spring migration phenology is still a challenge due to the lack of long-term precise location data. We used 11 years of Global Positioning System relocation data to determine four different migration dates of the annual migration cycle of the American white pelican (Pelecanus erythrorhynchos), a short-distance migrant. We also tested the hypothesis that increases in winter temperature and precipitation on the wintering grounds would advance pelican spring migration. Pelican spring departures and arrivals advanced steadily from 2002 to 2011. Spring departure timing exhibited high repeatability at the upper end of migration timing repeatability reported in literature. However, individual spring departure and arrival dates were not related to winter daily temperature, total winter precipitation, and detrended vegetation green-up dates indexed by the normalized difference vegetation index. Despite high repeatability, the observed between-year variation of spring departure dates was still sufficient for the advancement of spring departure timing.

Seasonal effects of climate and land use changes on ecological niche of a migratory bird

“…Because we wanted to analyse the use of habitat by AWPE in their breeding and wintering grounds, we excluded from analyses the tracking locations during seasonal migration. A given individual was considered in spring migration (departure from wintering range) when it crossed 35 o N latitudinal line northward, de ned as the northern boundary of the wintering range, until it reaches the breeding grounds (see King et al 2017), and vice versa in autumn. For the purposes of this study, we assumed that migration ended when the given individual entered the breeding (spring) or wintering (autumn) region and began moving locally as it searched or settled into a particular breeding site (King et al 2017).…”

“…A given individual was considered in spring migration (departure from wintering range) when it crossed 35 o N latitudinal line northward, de ned as the northern boundary of the wintering range, until it reaches the breeding grounds (see King et al 2017), and vice versa in autumn. For the purposes of this study, we assumed that migration ended when the given individual entered the breeding (spring) or wintering (autumn) region and began moving locally as it searched or settled into a particular breeding site (King et al 2017). In addition, and to ensure that we exclude from analyses those locations where AWPE were ying at higher altitude above ground, we also excluded from analyses those locations in the upper decile of ying speed (Gutierrez Illan et al 2017).…”

“…American white pelicans are divided into eastern and western metapopulations by the Continental Divide (Anderson and King 2005). We focused on the eastern metapopulation of the AWPE, which shows a facultative, mid-range migration between the Northern Great Plains (the nesting grounds) and the Southern Gulf of Mexico (the wintering grounds) along the Mississippi and Ohio River Valleys (King et al 2017, Shannon et al 2002. The mechanisms that control this facultative migration (e.g.…”

“…The mechanisms that control this facultative migration (e.g. resident individuals at the wintering or nesting grounds year-round) is still unknown (King et al 2017). Since the 1990's, AWPE has been known to use commercial aquaculture ponds consistently for feeding primarily on cat sh (King 2005).…”

Testing alternative methods for estimation of bird migration phenology from GPS tracking data

“…The simplest one is the S method, in which birds reach or leave the breeding or wintering grounds after crossing Y latitude or boundary (López‐López et al , Hewson et al , Illan et al , King et al , Monti et al ). The AD method, which may incorporate a spatial threshold as well, sets the start of migration as the first day at which daily displacement (i.e.…”