# The First Record of Taiga Shrew in Lithuania

## TL;DR

Scientists found the first taiga shrew in Lithuania, suggesting it may live in the Baltic region and needs more study.

## Contribution

This is the first documented occurrence of the taiga shrew in Lithuania, expanding its known range.

## Key findings

- The taiga shrew was identified in Lithuania through morphological and cranial analysis.
- The species' western range boundary has been extended by 200–630 km into the Baltic region.
- The finding suggests underreporting of the species and the need for genetic and survey follow-up.

## Abstract

We report the first record of the taiga shrew (Sorex isodon) in Lithuania, expanding its known distribution westward into the Baltic region. The specimen was collected in 2023 during non-systematic trapping and identified through external morphology and cranial traits. Identification relied on tail structure and distinctive skull features, with confirmation supported by expert consultation. This finding suggests possible habitat suitability and underreported presence of the species in Lithuania. It also highlights the need for further surveys, re-evaluation of skull collections, and genetic identification of the species to better understand its presence in the region.

The taiga shrew (Sorex isodon), a boreal forest species widely distributed across northern Eurasia, had not previously been recorded in the Baltic states. We report the first occurrence of S. isodon in Lithuania, which extends the species range westward into the Baltic region. The specimen, which was initially misidentified as Sorex araneus, was collected in 2023 near Vilnius during non-systematic snap-trapping. A detailed examination of tail, cranial, and dental characteristics confirmed the identification as S. isodon. The individual was a non-adult male, weighing 5.8 g, and was trapped in a wet mixed forest influenced by beaver activity. This suggests that the microhabitat conditions are similar to those reported in Belarus and Ukraine. This finding extends the western boundary of S. isodon distribution by approximately 200–630 km. This study underscores the potential underreporting of this species in the Baltic region and highlights the importance of revisiting existing skull collections, conducting targeted trapping, and performing genetic analyses. Verifying additional records will clarify the habitat preferences and conservation relevance of S. isodon at the western edge of its range.