Very little around in my first quick drive around, nothing on the football pitches or in the trees by the river - where are all the Siskins? It was 9:30 and there were far too many people around already.
However there was a lovely Song Thrush in the northernmost of the three tall limes by the River Bourne behind Elgar block, in fairly full song. And there was a lusty robin singing in the
Betula utilis on the path between the Canteen and the Garden Centre.
And then, very encouragingly, I saw a tiny bird flying, undulating slightly, across the College Drive into the three pines by the bike sheds. I was in two minds whether to check on it, but I did follow it up discreetly and to my great pleasure it was a Treecreeper,
Certhia familiaris, hopping up the trunks of the pine trees by the bike sheds, one tree after another, wonderful views and actions. I didn't have a camera with me, but I will include a picture taken 3 years ago in the trees in Meadows Field beside the River Bourne on a very snowy day. The white supercilium, the sharp, laterally flattened, beak ideal for probing bark, and the complex pattern on the back of the bird giving it excellent camouflage, all show quite clearly in this photo:
The picture is of a Common or Eurasian Treecreeper, a tiny species of bird which hops UP the side of tree trunks finding insects in the bark crevices, propping itself against the bark with its stiff tail pushing against the grip of its claws. Personally I only see a few of these, if any, a year, as they are very small, quiet, brown and quite inconspicuous, but they are definitely not uncommon birds, widespread and often use larger suburban/rural gardens, parks or woodland where enough older trees are found and insecticides not much used, if ever. The RSPB suggests there may currently be 200,000 territories in the UK, and numbers seem to be on the up in the UK, if anything.
They are VERY fond of trees with crusty bark like Giant Redwood, etc., and they are likely to do well in the tree collection around the College Grounds. They may roost in holes excavated out of Giant Redwood bark. I haven't also seen them passing through my own tiny back garden, where I try to keep a fairly good tree coverage. They are good parents and may raise two broods a year, nesting in old tree bark or woodpiles. British birds, which are said to be of the subspecies brittanica, are said to tend not to migrate or move around very much once settled in territories, and with individual breeding territories of say about 4 Hectares of woodland, only 200 m x 200 m, within larger areas of woodland, I reckon this bird might perhaps never have been out of the College grounds in its life (totally dependent upon the habitat within the College), and at any one time there are likely to be several birds most years across Broadview gardens and around the college buildings and nearby gardens. However an alternative view is that they do wander quite a bit in the winter, and this may be exploring the College from a base in the woods.
They often join flocks of tits in the winter, and may be quite mobile at that season. Bird Study (1989) 36, 99-104. The exploitation of Tits
Parus species, Long-tailed Tits
Aegithos caudatus and Goldcrests
Regulus regulus by Treecreepers
Certhia familiaris: a behavioural study. I.G. Henderson, The University of Leicester. The variation of Treecreeper
Certhia familiaris pecking rates was studied in response to variations in the size of associating flocks of Tits
Parus species, Longtailed Tits
Aegithos caudatus and Goldcrests
Regulus regulus. A significant and positive relationship was detected. The actual frequency of association between tits and Treecreepers was investigated, and the analysis and discussion of niche separation and the effects of temperature are also included. It is suggested that increased vigilance afforded by associating with tit flocks allows Treecreepers to adjust their own time budget, away from vigilant behaviour and towards extra feeding. This paper suggests that if the experimenter saw a flock of Tits in the winter, the majority of them did not contain Treecreepers. However the majority of Treecreepers seen in the winter during this research were seen in a Tit flock. The flocks tended to be bigger in colder weather, but after temperature was accounted for, the pecking rate increased in larger flocks, suggesting that the advantage of associating in flocks allowed the Treecreeper to concentrate more on feeding than on vigilance. The Treecreeper is of course not feeding within the same niche as the Tits.
Warren tends to see them very regularly in the Wet Woods and Scrubby Woods, although they do come into his garden, fairly close to some woodland, from time to time as well, where they search for food in a (obviously rough-barked) elder tree. In general they can be thought of as old-growth woodland birds, that may be quite strongly impacted by habitat fragmentation and urbanisation. Woodland fragmentation tends to impact upon nesting success via nest predation (e.g. mustelids), which is often significant, according to Finnish experimentation. The species was also shown by long-term monitoring to be gradually lost from around the Brent Reservoir as the area was built over. Not generally to be found on bird-tables!
Treecreepers are probably most closely related to wrens, a relationship that fits with their size and colouring. Treecreepers have very long rear claws (long curved nails), which presumably help them to grip the bark more easily. The beak is quite scythe-shaped, mainly pale on the lower mandible (especially hear the base), and dark on the upper mandible. The bright buffish "zigzagy" band with dark edges on the wing is quite visible, this runs across the base of the secondaries and the middle of the primaries. The spotty bars further forward on the wing are also quite clear, which I think are the tips of the greater and lesser coverts. The thin streaky patterns on the cap are also quite reliably seen.
The British form or subspecies is known as britannica. It is darker than the nominate continental form C. f. familiaris, commonly found across Northern Europe, and also further East in Europe. It is also duller, with less obvious ghostly marks on the upperside, duller white underneath, and in some individuals buffy under the tail. The juvenile is rather spottier as opposed to streaky on the upperparts when compared to the adult, and the underparts are again a duller white, as well as distinctly buffier under the tail. There are at least half a dozen more subspecies across Europe as a whole.
I hope to see this one, its mate, or perhaps some of their young, again in 2015 if I keep my eyes open in the grounds. It should nest in April/May or so, if it can find a mate and a suitable nest site. The males may court the females by a delicate spiralling dance around a tree, and wing-fluttering. They are generally monogamous, but with the females doing most of the nest building and care of the young.
Voice high-pitched and sibilant.
They may live for up to 7 years, say.
Food availability and the male's role in parental care in double-brooded Treecreepers
Certhia familiaris. Markku Kuitunen, Ari Jäntti, Jukka Suhonen and Teija Aho. The aim of this work was to examine differences in paternal and maternal care in a double-brooded, monogamous species, the Treecreeper
Certhia familiaris, in relation to food availability. As a measure of parental care, we recorded the hourly feeding activity of parents when the nestlings from their first and second breeding attempts were 7 and 12 days old. Feeding frequency of the first brood increased with the age of the nestlings and also with the brood size when 12 days old. While the feeding activities of the females were similar with respect to the first and second broods, the males were less active and failed to provide any food to their nestlings in 15 cases out of 28 second broods. In spite of this, the fledglings from the second broods were heavier than those in the first. Such a pattern of male behaviour was possible without being a disadvantage to the chicks because the food supply increased during the breeding season and the female could provide food for the young alone. Thus paternal care was particularly important in times of poor food supply, i.e. during the first brood, where the extent of these males' activity in feeding the 7-day-old nestlings was positively correlated with the average mass of the nestlings. Our results support the idea that the male of monogamous, altricial bird species often makes important contributions to raising the young, especially during periods when it is difficult for the female to do so alone. Males show flexibility in their pattern of parental care, and male Treecreepers change their contribution to the first and second broods within the same season.
The birds move from tree to tree, said to be maintaining an overall direction of travel. They may tend to be found on the more substantial trunks. The flight from tree to tree may involve quite acrobatic braking and swooping to land on the next tree. Title: Effects of male removal on female foraging behaviour in the Eurasian Treecreeper. Author: Aho, Teija ; Kuitunen, Markku ; Suhonen, Jukka ; Hakkari, Tomi ; Jäntti, Ari Behavioral Ecology and Sociobiology, 1997, Vol.41(1), pp.49-53
In old, spruce-dominated forests of central Finland, Eurasian Treecreepers
Certhia familiaris divide their territories spatially during the breeding season. Females forage primarily on the upper parts of the tree trunks, while males use the lower parts of the tree trunks. In this study we removed males from eight territories in the early nestling period to see if the mate's absence would change the foraging patterns of the resident female. Widowed females foraged at lower heights, thus behaving more like paired males. These females also spent less time on each tree and on each foraging bout than did paired females. We conclude that male removal facilitated the change in a female's foraging niche and foraging time at the trees. Females may re-optimize their foraging site selection owing to the absence of dominant males and a consequent need to increase their parental care. Behavioral plasticity may be the mechanism of niche partitioning between the sexes in this species.
The adults have one complete moult after breeding, later in the summer. The juveniles have a partial moult, actually fairly quickly after fledging, retaining their wing feathers until the following year's moult.
