Just one nest usually includes someone anywhere between brief-distance migrants one remain local and only move to winter season roosting internet sites fifty kilometres out, doing international a lot of time-point migrants travelling thousands of kms (Shamoun-Baranes mais aussi al., 2017 ; Stienen ainsi que al., 2016 ; Thaxter et al., 2019 ). One’s wintering area is assumed as uniform across decades and that is unrelated to possibly gender otherwise dimensions (Baert ainsi que al., 2018 ). Reduced black-supported gulls are designed for playing with a range of resource designs, in addition to phuysen et al., 2015 ), no matter if contained in this confirmed months, lots of people have a tendency to specialize to your a particular foraging approach (Camphuysen ainsi que al., 2015 ; Isaksson mais aussi al., 2016 ). Having the capability so you can forage inside a general directory of habitats and you can endure inside the a variety of weather will bring of several potential solutions with regards to exactly how, where and when they migrate.

dos Materials And techniques

Playing with a lengthy-name, high resolution GPS-record dataset off minimal black-backed gulls reproduction within the colonies into the Belgium, the uk and Netherlands, with people that happen to be monitored to have multiple ages, we mentioned type throughout the following migratory behaviours: non-reproduction shipment, fine-size wintering website fidelity, migratory routes and day regarding coming and departure from breeding and you will wintering portion. Among advantages of the investigation experience the fresh new higher spatio-temporal resolution of your research across the all territories (every hour from the ±step three meters spatial solution) that allows me to truthfully assess from the a fine spatio-temporal measure all the migratory behaviors i analyzed. Our very own earliest objective will be to quantify inter- and you will intra-individual variation ones migratory behaviors within the smaller black colored-backed gulls and determine if or not someone fool around with uniform measures. Whenever you are various behavioral choice tends to be accessible to a keen personal, you can find benefits to performing constantly in proportions and you can date (Gunnarsson mais aussi al., 2004 ; Piper, 2011 ). Therefore, we hypothesize that people will generally remain consistent within their migratory actions, with people adaptation are mainly a direct result inter-individual differences. The next goal should be to determine whether individual variation from inside the migratory behavior alter with migration distance. Discovering version in migration habits within individual-level, a premier spatio-temporal solution and you will together such a standard range migration distances have rarely already been you’ll be able to, making it possible for us to target that it matter of an alternate environmental perspective.

dos.1 Record and you can analysis processing

We utilized GPS tracking research away from adult lesser black-supported gulls monitored for two or even more many years regarding seven colonies regarding the Netherlands, Belgium and the Uk (Table step one, Shape 1). Gulls was indeed captured in reproduction seasons playing with go-for the traps place along side colony throughout the incubation. Further actions was indeed registered using solar power-pushed GPS-trackers (UvA-Pieces, Bouten mais aussi al., 2013 ), attached to a Teflon wing utilize (Thaxter ainsi que al., 2014 ). Overall size out-of tracker and you will funnel have been less than step three% out-of full human anatomy mass.

The new reproduction year try defined as that time of the season when one happens in the new breeding colony, irrespective of their breeding condition. The new non-breeding year therefore starts with time from colony departure (last detection within this 10 km of reproduction nest after the reproduction year) and you will goes on up to big date away from nest coming (very first detection inside ten km of your nest prior to the reproduction year). In order to measure day spent in various areas in the non-breeding season (non-reproduction shipment), we computed a good usage shipping (UD) on 95% kernel occurrence rates from GPS metropolises taken in the low-breeding seasons. Tracking analysis were subsampled so you can an effective a dozen-hours interval to attenuate autocorrelation and help distributed data equally as a consequence of big date (regarding multiple-big date studies openings) and you may was indeed estimated to a good Lambert equivalent-urban area projection (EPSG 3035). UDs manufactured making use of the r package ‘ adehabitat HR’ (Calenge, 2006 ) with a great bivariate normal kernel into an excellent grid having good ten-kilometer quality, using a predetermined bandwidth (h) of a hundred kilometres.