Authors: Nicholls, Sarah ;Ewen, John G;Gottelli, Dada;Grueber, Catherine E. ;Santure, Anna;Trask, Amanda;Brekke, Patricia;

Translocations can facilitate gene-flow between fragmented populations, introducing new genetic variants that mask deleterious alleles and relieve inbreeding depression (i.e., ‘genetic rescue’). Yet, genetic rescue attempts in threatened populations are underutilised due to uncertainties surrounding outbreeding depression, appropriateness of donor and recipient populations and the duration of beneficial effects. The New Zealand hihi is a threatened passerine with low levels of genetic diversity, whose recovery is hampered by disease outbreaks and reproductive failure. We assessed the long-term (10 years) outcomes of gene-flow through the translocation of 20 immigrant hihi from the last remaining natural population to a reintroduced, pedigreed population on the island of Tiritiri Mātangi. Six immigrants bred, two of these were closely related and only three have descendants in the population 10 years on. One female immigrant left significantly more descendants and is related to over 50% of the breeding population, which was associated with an increase in mean inbreeding level, but we found no evidence that inbreeding depressed early-life survival. Genetic diversity across 18 microsatellite loci increased, but no detected changes in immunogenetic heterozygosity across three Toll-like receptor genes. We highlight the importance of long-term monitoring of translocations that attempt genetic rescue.