A chromosome-level genome assembly of the Eurasian great grey owl, Strix nebulosa lapponica (Thunberg 1798).

We present a chromosome-level genome assembly of a female great grey owl (Strix nebulosa lapponica). The assembly comprises two pseudo-haplotypes of 1554 Mb and 1242 Mb, with 83.2% and 91.4% scaffolded into 40 autosomal chromosomes, in addition to the Z and W sex chromosomes both placed in hap1. Assembly completeness is high (BUSCO 99.2% and 94.8%), with 18,493 and 17,279 annotated protein-coding genes for hap1 and hap2, respectively. This genome establishes a reference for investigating genetic variation and chromosome evolution in great grey owls. Compared with the previous S. nebulosa assembly, this assembly includes both sex chromosomes, separates regions that were previously misassembled, and supports a diploid chromosome number of 2n = 82. While larger chromosomes show broadly conserved synteny across owl assemblies, the recovery of additional conserved dot microchromosome-associated marker proteins suggests that ONT reads improved resolution of the smallest chromosomes relative to HiFi-based assemblies.