First Insights into the Home Range of an Adult Male Mediterranean Monk Seal Monachus monachus in the Ionian Sea, Greece, and Considerations About the Future Management of the Area

TL;DR

An adult male Mediterranean monk seal moves between islands in the Ionian Sea, suggesting conservation efforts should cover a larger area.

Contribution

This study provides the first documented insights into the home range of a male Mediterranean monk seal in the Ionian Sea.

Findings

The seal was observed using marine caves on Kefalonia and Zakynthos, 15 km apart.

Conservation measures should consider the entire area as a single unit rather than isolated sites.

A network of protected marine caves with buffer zones is needed to cover the species' home range.

Abstract

An adult male Mediterranean monk seal repeatedly used marine caves for resting on two islands in the Greek Ionian Sea, about 15 km apart—Kefalonia and Zakynthos. This distance can be considered as the minimum distance within the home range of the animal that needs to be taken into account within the framework of the ongoing elaboration of conservation measures.

From August 2021 to December 2023, one adult male Mediterranean monk seal was repeatedly registered, through a systematic monitoring camera system, frequenting a marine cave in southern Kefalonia Island, central Ionian Sea, Greece. The presence of the same adult seal in a series of caves and overhangs in a bay in northwestern Zakynthos, southern Ionian Sea, in September 2023 and May 2024 was verified through opportunistic surveys and citizen science. The two locations are ca. 15 km apart and each is located in a different marine NATURA 2000 site. Appropriate conservation measures need to take into consideration the fact that seals do move between Kefalonia and Zakynthos (and possibly also other Ionian islands) and that the entire area has to be considered as a single “conservation unit” rather than elaborating protection measures on a small scale around a couple of resting and pupping caves alone. A full network of marine caves under strict protection surrounded by a buffer zone, taking into account at least the species’ home range, is needed in order to substantially cover the monk seal’s critical terrestrial habitats throughout the Ionian Sea.

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