The Eurasian nuthatch (Sitta europaea) is a small passerine bird known for its remarkable agility in climbing tree trunks, often descending head-first, a unique trait among birds. Its plumage features a bluish-grey upper part, with rusty-orange underparts. A distinctive black stripe runs across its eyes, giving it a striking appearance. The nuthatch has a short, sturdy, and pointed beak, perfect for foraging insects and seeds hidden in bark crevices.

Scientific Classification:

• Kingdom: Animalia
• Phylum: Chordata
• Class: Aves
• Order: Passeriformes
• Family: Sittidae
• Genus: Sitta
• Species: Sitta europaea

Dimensions and Weight: The Eurasian nuthatch measures between 12 and 14 cm in length, with a wingspan of 22-27 cm. It weighs between 17 and 25 grams. Its compact and stocky body enables it to move nimbly up and down trees.

Habitat: The Eurasian nuthatch primarily inhabits deciduous and mixed forests, but it also thrives in parks and gardens. It is distributed across much of Europe and temperate Asia, favoring areas with mature trees, particularly oaks, beeches, and pines, where it can find insects and nest in natural cavities.

Behavior and Habits: The Eurasian nuthatch is known for its ability to move both up and down tree trunks, a behavior rarely seen in birds. During the summer, its diet consists mainly of insects, while in autumn and winter it shifts to seeds and nuts, often hiding them in bark crevices for later consumption. It is a territorial and monogamous bird; pairs often remain together for several years and defend their territory year-round. The breeding season runs from March to July. The nuthatch nests in natural cavities or abandoned woodpecker holes, sometimes sealing the entrance with mud to reduce its size and protect the nest.

Dangers, Enemies, and Threats: Natural predators of the Eurasian nuthatch include birds of prey, small predatory mammals, and snakes that may raid nests for eggs or chicks. However, the primary threats to the species come from habitat loss due to deforestation and the reduction of old trees with suitable nesting cavities. In some regions, increasing urbanization and the removal of dead trees have reduced available nesting sites.

Protected or Endangered Species: The Eurasian nuthatch is not currently considered globally threatened, but the conservation of mature forests is essential to maintaining stable populations. In certain European regions, conservation projects aim to preserve its natural habitats, especially in areas where deforestation is more prevalent.

References__________________________________________________________________________

Galván I. Condition-dependence of pheomelanin-based coloration in nuthatches Sitta europaea suggests a detoxifying function: implications for the evolution of juvenile plumage patterns. Sci Rep. 2017 Aug 22;7(1):9138. doi: 10.1038/s41598-017-09771-4.

Abstract. Adult-like juvenile plumage patterns often signal genotypic quality to parents. During adulthood, the same patterns often signal quality to mates. This has led to assume that adult-like juvenile plumage is a developmental consequence of sexual selection operating in adults. Many of these patterns are produced by the pigment pheomelanin, whose synthesis may help remove toxic excess cysteine. Excess cysteine is likely to arise under conditions of relatively low stress, such as those experienced by nestling birds. Thus, adult-like plumage may be advantageous for juveniles if produced by pheomelanin. In the Eurasian nuthatch Sitta europaea, juveniles are sexually dichromatic and identical to adults. Nestling nuthatches in poorer condition develop more intense pheomelanin-based feathers, indicating greater pigment production. The same is not observed in adults. This is contrary to a function related to signaling quality and instead suggests that, at least in the Eurasian nuthatch, adult-like juvenile plumage has evolved because of the detoxifying function of pheomelanin-based pigmentation. Given the prevalence of colors typically conferred by pheomelanin in juvenile plumage patterns, the detoxifying capacity of pheomelanin under low stress levels should be considered as an explanation for the evolution of both adult-like and distinctively juvenile plumage patterns.

Zink RM, Drovetski SV, Rohwer S. Selective neutrality of mitochondrial ND2 sequences, phylogeography and species limits in Sitta europaea. Mol Phylogenet Evol. 2006 Sep;40(3):679-86. doi: 10.1016/j.ympev.2005.11.002. 

Abstract. Variation and geographic differentiation in mitochondrial DNA (mtDNA) was studied in the widespread and phenotypically variable Eurasian nuthatch (Sitta europaea). To assess whether sequences were evolving in a selectively neutral fashion, we used McDonald-Kreitman [Nature 351 (1991) 652] tests and a tree-based method, which suggested that although ND2 sequences are affected by natural selection against slightly deleterious alleles, the effects do not compromise phylogeographic inferences. Three phylogenetic species-level clades of nuthatches were discovered, corresponding to the Caucasus, southern Europe, and northern Europe plus Asia. Unimodal mismatch distributions within each clade suggest that populations have undergone recent growth. A westward range expansion was inferred from the geographic pattern in nucleotide diversity. Although samples were insufficient, it is possible that nuthatches in England and Japan are recently differentiated. Two specimens of the subspecies S. e. arctica formed a sister group to all other S. europaea, differing by ca. 10% uncorrected sequence divergence, pointing the need for additional study of this phenotypically distinct taxon. As with other species, mtDNA data support major phenotypic distinctions, but not subspecies.

Bellamy PE, Brown NJ, Enoksson B, Firbank LG, Fuller RJ, Hinsley SA, Schotman AG. The influences of habitat, landscape structure and climate on local distribution patterns of the nuthatch (Sitta europaea L.). Oecologia. 1998 Jun;115(1-2):127-136. doi: 10.1007/s004420050499. 

Abstract. The nuthatch, Sitta europaea L., is a small (23 g), cavity-nesting woodland bird which, since the 1970s, has been expanding its range in Britain. However, within this range, the species is notably scarce in an area of eastern England. This gap in the species distribution could arise for several reasons including habitat quality, local landscape structure, regional landscape structure and climate. Field surveys and logistic models of breeding nuthatch presence/absence were used to investigate the relative influences of habitat quality, landscape structure and climate on the prevalence of nuthatches in eastern England. Field surveys of woods in the study area indicated that habitat quality was sufficient to support a nuthatch population. A model of habitat occupancy in relation to local landscape structure, developed in the Netherlands, was applied to the study area. The number of breeding pairs predicted for the study area by the model was lower than expected from habitat area alone, suggesting an additional effect of isolation. However, observed numbers were even lower than those predicted by the model. To evaluate the possible roles of climate and large-scale landscape structure on distribution, presence/absence data of breeding nuthatches at the 10-km grid square scale were related to variables describing climate and the amount and dispersion of broadleaved woodland. While climate in the study area appeared suitable, models including landscape variables suggested that the study area as a whole was unlikely to support nuthatches. Although suitable habitat was available, woodland in the study area appeared to be too isolated from surrounding nuthatch populations for colonisation to be successful. This situation may change if current increases in both national and regional populations continue, thus increasing the number of potential colonists reaching the study area.

Bartošová L, Trnka M, Bauer Z, Možný M, Stěpánek P, Zalud Z. Phenological differences among selected residents and long-distance migrant bird species in central Europe. Int J Biometeorol. 2014 Jul;58(5):809-17. doi: 10.1007/s00484-013-0661-z. 

Abstract. The phenological responses to climate of residents and migrants (short- and long-distance) differ. Although few previous studies have focussed on this topic, the agree that changes in phenology are more apparent for residents than for long-distance migrants. We analysed the breeding times of two selected residents (Sitta europaea, Parus major) and one long-distance migrant (Ficedula albicollis) from 1961 to 2007 in central Europe. The timing of the phenophases of all three bird species showed a significant advance to earlier times. Nevertheless, the most marked shift was observed for the long-distance migrant (1.9 days per decade on average in mean laying date with linearity at the 99.9% confidence level). In contrast, the shifts shown by the residents were smaller (1.6 days for S. europaea and 1.5 days for P. major also on average in mean laying date for both, with linearity at the 95% confidence level). Spearman rank correlation coefficients calculated for pairs of phenophases of given bird species in 20-year subsamples (e.g. 1961-1980, 1962-1981) showed higher phenological separation between the residents and the migrant. This separation is most apparent after the 1980s. Thus, our results indicate that the interconnections between the studied phenological stages of the three bird species are becoming weaker.