The crested tit (Lophophanus cristatus), a characteristic bird of the native pinewoods, has increased in numbers with the expansion of Scots pine plantations.
Global distribution
The crested tit occurs from the Iberian Peninsula, France and Scotland across Europe and western Russia to the Ural Mountains. Within that, its range stretches from about latitude 66° N in Scandinavia to the mountains of northern Greece and the Balkans. The population in Scotland is geographically isolated from those on mainland Europe, and the differences between the populations have resulted in the Scottish birds being classified as a distinct subspecies (Parus cristatus scoticus). Other subspecies have been identified in western France and the Iberian Peninsula.
Distribution in Scotland
In Scotland, the crested tit is confined to Caledonian pine forest remnants and pine plantations in Easter Ross, the Beauly catchment (which includes Glen Affric), Strathspey and the Moray Firth coast. It is missing from some of the ancient pinewood remnants, including those on Deeside and at Rannoch, but the reasons for this are not clear, as suitable habitat exists there. The poor dispersal ability of the species has been suggested as one possible reason for this – the geographical isolation of the forest fragments has resulted in large gaps of treeless ground which the birds are unable to cross in sufficient numbers.
The population in Scotland has increased in recent decades, as a result of the expansion of pine plantations. Following three years of study by the Royal Society for the Protection of Birds (RSPB) between 1992-95, it was estimated at 7,000 individuals. About one third of this number were in Caledonian pine forest remnants, with the remainder occurring for the most part in plantations of Scots pine (Pinus sylvestris). However, the density of birds in the native pinewoods was almost ten times that of the plantations, thereby indicating that the ancient forest provides a much more favourable habitat.
In the past, before most of the Caledonian Forest was cleared, it is likely that crested tit numbers were substantially greater than those of today.
The crested tit is a small bird between 11-12 cm. in length, with a wingspan of 17-20 cm. and weighing between 10-13 gm. The plumage is brown on the upper parts and whitish-grey on the underside, with buff-coloured flanks. The head is greyish-white, with a black patch on the underside of the chin and a black stripe which goes through the eye and backwards on the head, before curving, in a parabolic shape, forwards again lower down. The distinctive crest, from which the bird derives both its common and scientific names, is chequered in black and white, and stands up prominently from the head. Male and female birds are similar in colouration, but juveniles are browner and their crests are less pointed.
The crested tit can live for up to seven years, but the average lifespan is much shorter, at two years, due to factors such as predation, starvation in winter etc. Vocalisations consist of a soft, purring trill, which is repeated as a song, and high-pitched 'zee-zee-zee' calls.
The crested tit is a resident, non-migratory species, and is sedentary – it generally remains in the area where it was born. A study in Strathspey showed that individuals have territories just under 14 hectares in size, and that territories can have considerable overlap with those of neighbouring birds. After breeding, the crested tit forms small social groups, consisting of a resident pair and the young from another pair. These sometimes form mixed feeding flocks with other species, such as the coal tit (Parus ater), treecreeper (Certhia familiaris) and goldcrest (Regulus regulus), when those birds pass through the territory of a group of crested tits.
The diet of the crested tit consists mainly of insects and spiders, and a wide range of species are taken. In the Caledonian pinewood remnants, foraging takes place on the trunks and large branches of the old pines, and also amongst the needles. The bird exhibits great agility in searching for food, with upside-down being as effective for foraging as a normal upright position. It has been suggested that the tit's preference for old trees may be due to the greater abundance of lichens on them – the lichens are fed upon by insects such as springtails and bark lice, and these are eaten by spiders, which, in turn, are an important food source for the crested tit.
In April, the diet is supplemented by Scots pine seeds, which are extracted from the cones as they dry and open on the trees. In autumn, moth larvae are an important food source, especially larvae of the bordered white or pine looper moth (Bupalus piniaria), which are common at this time of year. In winter, the crested tit forages for food in the heather (Calluna vulgaris) on the forest floor, and the greater abundance of heather in ancient pinewoods, compared to pine plantations, has been proposed as a reason for the higher density of birds in the former.
The crested tit caches food for later consumption – in the spring, pine seeds are stored, and in the autumn, moth larvae are stored, usually under lichen on the branches of trees. This is thought to be a strategy to help the bird survive through the winter, when food is scarcer.
Breeding usually begins in late March, when a pair of birds will search for a suitable nesting site. In most cases, this will be a hole in a standing dead tree, or snag, which is excavated by the birds themselves. In the Caledonian Forest, nests are mainly in Scots pine snags, and these need to have been dead for about ten years in order for the sapwood (the section of the tree between the bark and the tough, inner heartwood) to have been softened up enough by saprotrophic fungi for the birds to excavate a nest chamber.
Because pine snags can persist for several decades before falling, an individual snag will be reused, although a new nest chamber will be excavated each time. The crested tit has also been recorded using old nest holes made by the great spotted woodpecker (Dendrocopos major) and dreys made by the red squirrel (Sciurus vulgaris).
Excavation of the nest chamber takes about three weeks, and is done exclusively by the female. Another five or six days are spent making the nest from moss, with glittering wood-moss (Hylocomium splendens) mainly used for this. Lichens, deer hair, spiders' webs and occasionally feathers are used to line the nest cup. In late April or early May the female lays between four and eight small eggs, which are white with reddish-brown speckles, and measure 16 mm. by 13 mm. These are incubated by the female for 13-16 days, before hatching in mid- to late May. The young are initially fed by both parents, but at some stage one or other adult will take sole responsibility for bringing food to the nest. The chicks fledge 17-22 days after hatching, and are dependent on their parents for about another 23 days, with whom they forage for food.
As a mainly insectivorous bird, the crested tit plays a role in regulating the populations of forest insects and other invertebrates, including the pine looper moth, whose larvae sometimes reaches pest proportions in pine plantations. The much higher density of crested tits in native pinewoods, together with the presence of other caterpillar-eating species, such as wood ants (Formica aquilonia and F. lugubris), may explain why the pine looper moth is not a serious pest in the Caledonian Forest.
Both the pine marten (Martes martes) and the red squirrel prey on crested tit chicks in the nest, and in one study 16% of nests were lost to predators. Adults are also vulnerable to predation, with the sparrowhawk (Accipiter nisus) being the raptor most likely to take a crested tit.
Parasites include two species of fleas (Ceratophyllus gallinae and Dasypsyllus gallinulae) which infest crested tit nests. The presence of these fleas is thought to be the main reason why a new nest chamber is excavated each year – reusing old chambers would result in a build-up of flea numbers to intolerable levels.
Because of their use of snags for nesting, the presence of the crested tit is an indicator of the ecological health of a forest, which should naturally contain standing dead trees. The current initiatives to regenerate and restore the Caledonian Forest should ensure that the crested tit continues to increase in numbers, and, in turn, that the ecological health of the forest benefits from the presence of this insectivorous bird.
