Naufraga balearica,a threatened narrow endemism of the Balearic Islands (western Mediterranean basin): assessing the population dynamics of two subpopulations

Naufraga balearica constitutes a monospecific genus of Majorca (Balearic Islands) and is Critically Endangered according to International Union for Conservation of Nature categories. The species has a narrow distributional area, with one subpopulation at Coves Blanques (CB) and a small set of subpopulations on the Formentor Peninsula. A previous work has shown that the subpopulation in Cap de Catalunya (CC) (located on the Formentor Peninsula) has undergone a distinct decline over the last decade. Herein, we report a comparative study of the population dynamics of N. balearica at the CB and CC sites. By monitoring permanent plots for 6 years (2004–2009), we analyzed the frequency of cells in which the species was present, and, for each annual transition (from November, year t to November, year t + 1), we determined the frequency of cells in which the species was stable, decreased or increased for each species and site using a G‐test of independence. The same parameters were also analyzed for N. balearica at the quarterly transitions of November–February, February–May, May–August and August–November. The results indicated that the decline of the threatened species was more marked in the CB subpopulation. N. balearica showed a seasonal trend at both sites, with some exceptions. The most common neighboring species were Dactylis glomerata and Erodium reichardii, and they negatively affected N. balearica; however, the neighboring species effect was not homogeneous among the annual transitions analyzed, indicating that other factors are involved. Finally, some conservation measures are proposed.