Eco-evolutionary consequences of dispersal syndromes during colonization in a passerine bird

In most animal species, dispersing individuals possess phenotypic attributes that mitigate the costs of colonization and/or increase settlement success in new areas (‘dispersal syndromes’). This phenotypic integration likely affects population dynamics and the direction of selection, but data are lacking for natural populations. Using an approach that combines population dynamics, quantitative genetics and phenotypic selection analyses, we reveal the existence of dispersal syndromes in a pied flycatcher (Ficedula hypoleuca) population in The Netherlands: immigrants were larger, tended to have darker plumage, bred earlier and produced larger clutches than local recruits, and some of these traits were genetically correlated. Over time, the phenotypic profile of the population gradually changed: each generation advanced arrival and breeding and exhibited longer wings as the result of direct and indirect selection on these correlated traits. Although phenotypic attributes of immigrants were favored by selection during the early phase of colonization, observed phenotypic changes were similar for immigrants and local recruits. We propose that immigrants facilitated initial population establishment but that temporal changes likely resulted from climate change-induced large scale selection. This study highlights that newly established populations are of non-random composition and that phenotypic architecture affects evolutionary population trajectories

Reproductive effort affects spatial distribution in Great tits

Poster at The Sixth International Hole Nesting Bird Conference. Oxford. Great Britain. July 2010 <br/

The hen harrier Circus cyaneus on Rottumeroog

The breeding behaviour of a Hen Harrier pair on the island of Rottemeroog is described. Rottemeroog is one of three small islands in the eastern part of the Dutch Wadden Sea (combined area c. 1050 ha, of which 232 ha vegetated). The pair was nesting in the overgrown garden of the former warden, a garden which was -in 1998- on the verge of being swallowed by the sea. During the winter of 1998/99 the major part of the garden disappeared into the sea and the pair did not breed on the island in 1999. The nest contained a completed clutch of 4 eggs on 24 April; the first egg probably hatched on 12 May (start of laying back-calculated at 11 April). On 20 June the first nestling fledged, followed by two others on 25 June; the fourth egg failed to hatch. Two juveniles left for the mainland on 17 July, the third fledgling remained on the island and fed on emaciated Starlings; up to 1000 Starlings roosted on the island from 25 June onwards. The adult female stayed on the island all the time. The adult male also visited Rottumerplaat and Zuiderduin (up to 5 km away), and made prolonged trips (lasting up to 2 days) to the mainland (&gt;l5 km away). The male never carried prey when returning from the mainland. During incubation several territorial conflicts were witnessed. On 25 April, an intruding adult female was chased away by the resident female, for which she had to leave the nest 7 times. A 2nd calender-year male tried to take over the resident female when the resident male was visiting the mainland on 28 April; this immature bird displayed and fed the resident female twice. After the adult male returned at 20.00 hr, both males fought intermittenly for several hours during which they interlocked claws and tumbled on the ground where they stayed for 1.5 hrs. Eventually, the intruder was chased away. During incubation, most prey was caught by the male, although the female hunted during absences of the male (at least once successful). After 15 June, the male stayed only rarely on Rottumeroog. During the nestling stage, 75 prey transfers were witnessed; the prey could be identified in 32 cases. The female took larger prey species than the male (Table 1). Near the nesting site, a plucking of a juvenile Magpie Pica pica was found, and the male was seen trying to capture a Turtle Dove Streptopelia turtur and juvenile Jackdaws Corvus monedula

Pallid Harrier Circus macrourus helper at the nest of a Marsh Harrier C. aeruginosus

In 2022, a male Pallid Harrier was recorded in farmland in the province of Groningen on 19 June when transferring a prey to a male Marsh Harrier. This bird had been colour-ringed as a chick in a nest of Pallid Harriers in 2019, less than two km away from the harrier’s presence in 2022. The Marsh Harriers had a nest in a wheat field. The nest was observed from a hide on 7 July, when five chicks of 1-12 days old were present. Between 8:45 and 13:30, a total of 22 prey deliveries were recorded (of which 18 were brought to the nest), five by Pallid Harrier, six by female Marsh Harrier and eleven by male Marsh Harrier. Except two birds, all prey were voles, presumably Microtus arvalis. Taking prey mass into account (25 g for Common Voles, 50 g for birds), each chick received 35 g of food per 100 minutes, of which the male Pallid Harrier contributed 10.4 g (30%). Furthermore, the Pallid Harrier was also frequently recorded chasing potential predators away from the nest site, including attacks on Marsh Harriers (other than the nesting pair), Buzzards Buteo buteo, Kestrels Falco tinnunculus, Carrion Crows Corvus corone and a Goshawk Accipiter gentilis. The nest eventually fledged four chicks. It is unknown whether extrapair copulations of female Marsh and male Pallid Harrier had taken place, which might have explained the Pallid male’s investment in the Marsh Harrier brood