Top 10 Facts: Willow Tit

Late discovery. The Willow Tit and the much more abundant Marsh tit are incredibly difficult to tell apart, even by professional birders. They are so similar, in fact, that they were once mistakenly believed to be a single species. Indeed, the Willow Tit was the last regular British breeding bird to be identified – only named in 1897. This split was largely due to observed differences in the calls of both species: Marsh Tits uttering a sneeze-like pitchou call, and Willow Tits a harsher zee-zurzur-zur.

Spot the difference. As time progressed, a number of ways to tell apart Marsh and Willow Tits were identified. For example, the cap of the former appears glossy compared to the duller tones of the willow, whose cap also extends further on to the nape. Similarly, the Marsh tits possess a larger bib; while the white cheeks of the Willow are often larger and more conspicuous than that of the Marsh. Additionally, Willow Tits also show a pale wing panel caused by the pale edging of the bird’s secondary wing feathers.

Habitat preference. Despite their name, marsh tits are known to prefer drier habits and are often found in expansive areas of broadleaf woodland – especially those boasting a prominent shrub-layer. Willow Tits, on the other hand, are associated with wetter areas, including wet-woodland. They are more likely to be seen in conifer forests also and are the species most likely encountered on disused industrial sites and wasteland areas boasting a healthy shrub layer. The Willow tit is absent from Ireland and much of Scotland but is known to occur further North than it’s close cousin.

Yet more confusion. In the past, the Willow Tit was considered to be conspecific with the Black-capped Chickadee of North America – another ascetically similar species. Confusion between the two species can be observed in the Peterson Field Guide to Birds of Britain and Europe. Here, the American species is listed as an alternate name for Willow Tit while, in reality, both species (alongside the Marsh tit and Carolina Chickadee) are only similar in appearance.

Conservation priority. Myriad reasons have meant that the British Willow Tit population has declined by 94% since 1970, with the species now completely absent from former haunts in the South-East and elsewhere in Britain. Populations in the North of England have suffered declines also but are clinging on due to the natural regeneration of wet scrub on old industrial land. Currently, the UK’s Willow Tit population is estimated at 3400 pairs, making this species on of the most pressing conservation issues in the UK today.

Susceptible to eviction. Evidence suggests that competition from Blue and Great Tits could be a major factor contributing to the decline of the Willow Tit in the UK. Willow Tits nest in cavities excavated from dead wood, with the nest building process often proving to be a very noisy affair. This, coupled with the obvious visual implications and the production of visible byproducts such as wood chips, means that excavating Willow Tits are vulnerable to detection from both the species previously mentioned. Both of which can extirpate the occupants of a nest with relative ease.

Are woodpeckers to blame? Once a nest hole has been excavated and lined, Willow Tits can still be noisy around their breeding site, leaving them vulnerable to detection by Great Spotted Woodpeckers, which are accomplished at extracting prey from rotten wood. Willow Tits are single-brooded and if predation occurs at the chick stage, the pair is extremely unlikely to breed again that year.  Numbers of Great Spotted Woodpeckers have increased dramatically in the UK (by 314% between 1970 and 2006), and
Willow Tits may have suffered a corresponding increase in predation rate.

Habitat loss. Despite a steep population decline, Willow Tits can still occur at relatively high densities in some brownfield sites where wet-scrub habitat is plentiful. Such disused industrial sites have, however, become less common in recent decades due to development, agriculture and natural regeneration. It is assumed that habitat loss is the primary driver of Willow Tit declines across Britain. Over-browsing by deer, which limits the regrowth of the species preferred wet-scrub, is almost certainly worsening the problem at many sites.

Novelty woodpecker. Willow Tits are the only British tit species to excavate a new nest hole each breeding season, with much of the work usually carried out by the female bird. Nests are positioned usually around a metre above the ground in a rotten stump and are established by the hen bird through boring and chiselling at the wood – prying off small chippings until the hole is widened sufficiently to enable breeding. Such nests are often lined with soft materials such as fur, moss or narrow strips of bark fibre. The particular nature of Willow Tit nests means that they seldom inhabit nest-boxes; though some people have successfully attracted the species by lining boxes with sawdust.

Claim to fame. The Willow Tit was featured in Gilbert and Sullivan’s 1885 operetta, The Mikado, in the song Willow Tit Willow. Sam the Eagle and Rowlf the Dog performed this in the first season of The Muppet Show.

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