Use of foster parents in species conservation may cause conflicting objectives: hybridization between Lesser White-fronted Goose Anser erythropus and Barnacle Goose Branta leucopsis

Niklas Liljebäck,Christine Kowallik,Johan Månsson,Åke Andersson,Kees Koffijberg

doi:10.34080/os.v31.22430

Niklas Liljebäck, Christine Kowallik + Show 3 more

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https://doi.org/10.34080/os.v31.22430

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Abstract

Following the use of Barnacle Geese Branta leucopsis as foster parents in a conservation program for the endangered Lesser White-fronted Goose Anser erythropus in Sweden 1981–1999, mixed breeding pairs of the two species were established in the wild. We find indications that this was related to shared moulting habits of the two species in the Bothnian Sea during late 1990s. Starting in 2003, five mixed pairs produced at least 49 free-flying hybrid offspring until 2013, when the last breeding was confirmed. Reported numbers of hybrids did not increase in parallel to the production of young hybrids over time. After 2013, the number of hybrids started to decrease in Sweden and the Netherlands. Lower numbers of hybrids than expected can partly be explained by management actions taken, but may also be associated with low survival due to genetic outbreeding. Mixed pairs and their offspring entirely adopted the migratory habits of Barnacle Geese, overlapping very little with sites used by Lesser White-fronted Geese. We find no evidence that the hybrids ever posed a serious threat to Lesser White-fronted Geese breeding in Fennoscandia.

Highlights

Introduction and backgroundHybridization has been highlighted as a potential threat to endangered taxa (Allendorf et al 2001, Jackiw et al 2015)
The Lesser White-fronted Goose is one of the goose species that has been observed to hybridize with other goose species
MIXED PAIRS OF LESSER WHITE-FRONTED AND BARNACLE GEESE BREEDING IN SWEDEN In total, six Lesser White-fronted Goose males (1.7 % of all released young with foster parents) were observed to produce hybrid offspring with Barnacle Goose females (Table 2, Figure 2)

Summary

Introduction

Introduction and backgroundHybridization has been highlighted as a potential threat to endangered taxa (Allendorf et al 2001, Jackiw et al 2015). One case where hybrids have gained special attention in relation to translocations concerns hybrids between Lesser White-fronted Goose Anser erythropus and Barnacle Goose Branta leucopsis (hereafter LWfG × BG). The existence of hybridizing pairs and their offspring have provoked disputes regarding the potential threat they may pose to the small, and highly endangered, populations of Lesser White-fronted Goose breeding in Fennoscandia ( Jones et al 2008). Either in the wild or in captivity (or presumably originating from captivity), have been reported with Greater White-Fronted Goose Anser albifrons, Greylag Goose A. anser, Snow Goose A. caerulescens, Bar-headed Goose A. indicus, Emperor Goose A. canagicus, Brent Goose Branta bernicla, Barnacle Goose, and Red-breasted Goose B. ruficollis (McCarthy 2006, Kampe-Persson & Lerner 2007, Nijman et al 2010, Ottenburghs et al 2016a, Ottenburghs 2017)

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