:Article https://doi.org/10.1038/s41467-025-56925-4
Sedimentary DNA insights into Holocene
Adélie penguin (Pygoscelis adeliae)
populations and ecology in the Ross Sea,
Antarctica:
Deeper in the article -
"SedaDNA also reveals prior occupation of the Cape Hallett Adélie penguin
colony site by southern elephant seal (Mirounga leonina), demonstrating how
terrestrial sedaDNA can detect faunal turnover events in Antarctica driven by
past climate or sea ice conditions."
Cape Hallett is 2,000km south of the current range of elephant seals.
"A high relative abundance of southern elephant seal was detected in
sedaDNA from basal (> 35 cm depth) sediments at Cape Hallett
(Fig. 6). A subsequent decline in the relative abundance of southern
elephant seal and increase in Adélie penguin was evident from both
mitochondrial and LCA approaches, and coincided with an
increasing abundance of penguin eggshell and ornithogenic soil
development (Fig. 6). The upper 10 cm of stratigraphy was unable to
be sampled for sedaDNA due to the lack of fine sediment, but as with
the ornithogenic soil layer below also contained common penguin
bones and feathers (Fig. 6). We suggest that the dominance of
southern elephant seal DNA in the basal sediments at Cape Hallett is
strong evidence for the former presence of a local breeding colony.
While individual southern elephant seals occasionally come ashore
on the Antarctic coast to rest 55,57 , such sporadic visitations would
likely result in DNA being detected only within a single depth hor-
izon. The relative dominance of elephant seal DNA spanning ~ 40 cm
of stratigraphy suggests a more sustained local presence of multiple
individuals, such as would be expected if a breeding colony were
present.
Southern elephant seal breeding colonies are currently restricted
to islands within the subantarctic region of the Southern Ocean.
However, the discovery of desiccated pup remains and hairs preserved
in sediments indicate the species formerly moulted and bred along the
Victoria Land Coast from Campbell Glacier in the north to Marble Point
in the south58
. Radiocarbon dating of elephant seal remains from the
Victoria Land Coast indicates that reduced sea ice extent between
~ 2500 and 1000 years ago allowed elephant seals to breed at these
southern latitudes and attain a large local population44,45 before
experiencing a local extirpation event that began in the south and
progressed northwards as sea ice expanded58,59"
https://www.nature.com/articles/s41467-025-56925-4.pdfI guess it was warmwer back then, and no runaway warming.

.