The White-backed Woodpecker Dendrocopos leucotos is one the rarest and the most vulnerable woodpeckers in Europe. Intensive forest practices have caused a widespread decline of the species. In the Spanish Pyrenees, on the south-west limit of the species range, a population of the lilfordi subspecies (Lilford Woodpecker) is estimated at less than 200 individuals which are confined to a few relatively well-conserved beech forests. Despite being an endangered taxon, our knowledge about the size and shape of its home range is still incomplete. Conventional radio-tracking studies of the taxon have been limited due to the complex topography of forests, whereas miniaturized GPS devices have not been available for such a small bird (∼100 g bodyweight) until recently. Here, we evaluate for the first time the utility of modern lightweight GPS tags to characterize the home range of the White-backed Woodpecker. Using 3.4 g GPS-tags we tracked movements of 14 adult individuals during the breeding and post-breeding periods between years 2017–2019. On average, the failure rate (the percentage of failed fix attempts) was 30%, and 76% of successful fixes were accurate (error extless 20 m). According to 95% kernel density estimator, the mean home range (∼300 ha) was several times larger than previously reported for the species, and it did not change over the post-breeding period. This finding challenges the utility of previous management recommendations for protecting small buffer areas around the nest or single forest stands. By modeling the home range size as a function of the number of fixes and errors, we found that males had significantly larger home ranges than females. Our results demonstrate that GPS telemetry is feasible in White-backed Woodpecker adults, and it can provide novel and accurate information about the home range of the species if potential sources of error are adequately addressed.