Winter losses amongst tits

The death rate amongst tits is very high in cold weather. As many as 80-90% of tits normally die in their first year of life, even in mild winter climates. The loss rate for mature birds is only 20 30%. It is important that loss of warmth during cold winter nights is minimised. More and more people are feeding protein-rich food to winter birds, which is an excellent thing to do. However, tits often like to spend winter nights in nest boxes, so boxes with good insulating properties should be set up in the vicinity of the feeding places. This helps the birds to use the short winter days more effectively, and avoids them having to squander energy on long flights or to waste precious food searching time.

The temperature in nest boxes can fluctuate a great deal, but good protection is afforded against wind, snow, and rain, A cotton wad can be laid inside the nest box, but this should be removed and thrown away in good time for the breeding season as the tits will also use the nest box as a toilet during the winter nights.

Tits sleep very deeply when it is dark and so do not use up many calories. They lay up stocks of food in advance and each species searches in those places where birds of its own kind habitually create such stores.

Of the 130 nest boxes I have set up, approximately 30% have been used by tits as overnight shelters in the winter.

Close study has revealed that the positioning of the nest box was a major factor in the bird's choice. If it is situated in ¿1 place where there is a Ice and sheltering woodland, then it will prove very popular as a night shelter.

Nest boxes for the small tit species, crested tit and coal tit, should be set up no more than 1 2 metres from theground. The willow tit does not normally breed in nest boxes, but hacks out its own nest in decayed tree trunks. However, if a nest box is set up at a height of one metre and one-third filled every year with wood shavings, then even willow tits can be persuaded to breed in the box. This sort of nest filling is a good imitation of the rotten wood found in old tree trunks and will also attract crested tits and coal tits to breed in nest boxes to a much greater extent than usual.

Great Tit (Parus major)

Favourite nest boxes for the great tit In my research area, great tits have really taken to the flycatcher model of'All-year' nest boxes, RF-nest boxes, as well as plank nest boxes which I have made myself.

Plank nest boxes 2 cm thick timber should be used. The internal depth should be 20 cm, the inner side measurements 15 cm, the entrance hole 3.5 4 cm, and the roof height 25 cm. The box should be set at a height 2.5 3 rn, but the direction in which the box is facing is of no particular significance in this case, except that, as with other nest box-inhabiting birds, a north-facing entrance is unpopular. A movable floor facilitates cleaning after the tits have finished each year and should always be included in the design if possible.

The great tit is one of the most common of our tits. The male and female have a similar appearance, though the female's colours arc somewhat paler. They are common in gardens, parks, and woodland, and during the winter they are the leaders of tit flocks, though tending to feed on the woodland floor while the smaller and more agile species remain more in the canopy.

Hormones influence the behaviour of the great tit and if it is sunnv, fine, and relatively warm, he will start his hoarse little melody as early as January or February. 1 have even heard great tits singing on New Year's after noon, as if they were ringing in the New Year. Being one of the first bird songs to be heard at this often dull time of year this hoarse but cheery little ditty acts a welcome harbinger of spring. You will hcartheir song as often in the town as in the country.

At the end of February, flocks of tits w ill break up and the male and

female will seek out the area where they bred in the previous year. Therefore, the same pair will often breed year alter year in the same nest box. If one of the couple dies, then its place is very quickly taken over by a new bird. Males which have only recently come to sexual maturity will look for left-over nest boxes and holes and will attempt to entice sexually mature females who are still unattached.

hrom the time that the young arc ready to fly, up to the new breeding period in the following year, the male and female live entirely apart. Great tits very much prefer sheltered, out of the way places for breeding and arc fussy when it comcs to choosing a nest box. They appear to have trouble in making up their minds and the male often starts constructing nests with a little fern and moss in several boxes at the same time until the female finally decides on one particular box. Sometimes he will build in starling nest boxes, sometimes even in goldeneyc boxes, in which case he fills up the entire bottom of the box with moss and ferns and builds the nest bowl in one corner. 1 oncc found a great tit nest in a letter box, which was large and rectangular and provided with a lid which did not shut properly, leaving a chink through which the great tit could pass. The bottom was completely filled with green golden maidenhair fern and in one corner lay a nest bowl with ten eggs.

At the beginning of April, the male starts to become aggressive towards males ol his own and even of other species; he is now maintaining his territory. However, he draws a line when it comes to the rather fierce pied flycatcher and blue tit. His submission to these two species even occurs when his female has laid eggs, though not so often when there arc young involved.

The nest is built by the female and takes six days to complete. It consists of mosses, ferns and dried grass. The interior is lined with a soft, warm material such as down, small hairs, horsehair, and wool.

The number of eggs varies from five to 12. When a full clutch has been laid, the female broods alone for 12 days, and during the egg laying and brooding periods, she will cover over the eggs whenever she leaves the nest. Though she is fed quite often by the male, she will leave the eggs for hours at a time in the middle of warm days, when she will seek out her own food.

Hven though for most of the year great tits will live in the immediate vicinity of humans, and in winter will even feed from the hand, they are very cautious and sensitive to disturbance during the nest building and incubation periods and when the young arc newly hatched. The female is strongly attached to her eggs, but if she becomes frightened, she will leave the nest and not return, and this should always be kept in mind.

For the most part, great tits feed on insects which arc pests in gardens, parks, and woodland. Each day they eat 2.5 times theirown body weight in the form of insect larvae. When it has young, a great tit can clear 80 90% of the moth larvae on an infested fruit tree, thus saving the tree's foliage.

In 1962 there was a plague of pine moths along the cast coast of Sweden and many pine trees were killed off in spite of aerial spraying. No pine trees died in my nest-box area, even though there had been no spraying there. In that particular year, six pairs of great tits and 16 pairs of pied flycatchers bred in the area, and all of them had fed to some extent on the pine moths; the great tits did so almost exclusively.

A pair of great tits with 8 half grown young will consume around 1000 insect larvae per day. The two parents together provide food about 400 500 times pcrday, with an average of two larvae each time. So in the 19 days that the young were in the nest up to 19,000 larvae may have been eaten, giving a total of about 114,000 for six pairs.

During the first two days the young arc fed every eight minutes, on the third day every five minutes, and from the fifth day every three minutes. This of course is assuming that there is acccss to a good supply of food, and the feeding schedule can vary from year to year and from pair to pair depending on the availability of food in the vicinity of the nesting place. If for any reason there is a dearth of insects, then the fatality rate will be very high among large broods of young.

The young of great tits need intensive care for the first 8 10 days of life, unlike young pied flycatchers which can manage without their mother's help by the second day. Without warmth from their mother's body, the small great tits will die, and during this period the male normally brings food to the female who then feeds the young.

If the pair are double brooded they will always raise their second brood in a different nest box. They know from past experience that the lirst batch in a nest box results in a nest bowl full of insects and mites and thoroughly soiled with the droppings of their young. Neverthless, as soon as possible after breeding is over, the nest box should be cleaned out and the used nest burned, otherwise the insect eggs laid there can survive the winter, and hatch out in the warmth of spring, thus re-infesting the nest box.

Once the young have left the nest, they stay with their parents for about a month, but this period is shortened to two weeks if the parents produce a second brood. Thereafter, the young join up with flocks containing tits, warblers, and flycatchers.

Of all the tils, the great tit is the one most likely to shelter overnight in nest boxes in autumn and winter. If the great tits are to survive the cold winter nights, the nest box must be well insulated, and the hollowcd-out section of trunk (so-called block nest box) and wood-cement board are the two best materials. Research shows that even during mild winters, losses amongst great tits in their first year can be as high as 87%, and in adult tits around 25% (Kluijver, 1951).

Great tits arc non-migratory birds and only move within a limited area during winter. However, ringing has shown that some great tits do make long journeys. Continental ringed great tits occasionally even turn up in Britain.

Besides warm living quarters, great tits also need calorie-rich food to survive the winter. Hemp seed, sunflower seed, and coconut fat arc the best foods for this purpose (sec page 192).

Blue Tit (Pants caeruleus)

Plank and block nesi boxes are the favourites for blue tits. The internal dcpthshould be 18 cm, thediamctcrof the floor 11 cm, and the entrance hole diameter 2.S cm.

The blue tit is a colourful little bird, with a grey-green back and crown and blue wings and rump. The underside is yellow and a blue black band runs along the chest. The chccks are white and bounded by a black and blue band which runs across the eyes, back to the neck, then under and foward to the chin.

The song is a pleasant trilling noise, which begins in spring as the blue tit hovers up and down, often in birch trees, looking for insects. The song and the mating call can sometimes ev en be heard above the din of city-traffic.

In the nesting place, whether an old woodpcckcr nest or a nest box. he is rather a combative little beggar and almost always manages to secure some living quarters. Great tils often give way to pied flycatchers when they arrive in thespring, bui only once in 29 years have I seen a blue tit do this. On the other hand, they cannot manage the wryneck, which will sometimes throw blue tits out of their nest box.

However, il the blue tit has a full clutch of eggs, it will almost always emerge victorious from any combat, the wryneck only rarely getting the upper hand. The tit's brooding behaviour is so strong that it will not leave the eggs. In such cases it will fight to the death if necessary. (Sadly this problem seldom if ever arises in Britain because there are now few breeding wrynecks left.) ir.vcn on bird tables it is stubborn and is often at

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Blue Tit the front of the queue for pieces of fat or coconut. It can hang upside down for long per iods while hacking away at its food.

Most blue tils are non-migratory, but some do fly abroad. Thcvcan often be seen in winter looking for pupae on the underneath of leaves. At the beginning of April, the blue tit starts looking for a suitable nesting place, and as soon as one is found, often a nest box if available, building commences. Only the female constructs the nest, which takes around seven days, and involves the fetching of about 4000 small loads of material.

The nest bowl consists mostly of moss and ferns on the outside, followed by horsehair, and finally small feathers and down which the female plucks from her own body to line the nest cup.

Immediately before and after nest building is completed one often sees the male court the female, who vibrates her wings and chirps submissively like a young bird. The female displays herself so as to show that she is nol aggressive like another male and to assure him that she will submit herself. The male feeds the female, as if she was still a young bird. It is all part of the mating ritual, but serves a useful biological function in thai it increases her protein intake prior to egg formation and laying.

Seven to 16 eggs are laid, with nine being the most normal number. The female lays one egg each morning, and when the clutch is complete the parents begin incubation. The female takes the major share of the brooding and is fed by the male either in the nest box or out in the trees around the nest box. She leaves the eggs unusually frequently during the day, and on some of these occasions the male takes over the brooding, though normally the nest is left empty. Sunshine, the insulation of the nest box. and the warmth of the nest all keep the eggs warm.

The eggs hatch after 12 days incubation. For the first four days the young arc fed by the parents between 4am and 8pm on average every eight minutes, l ike other tits the blue tits have about ten breaks during the day, of 15 20 minutes each, which means that the pair provide 190 meals per day, cach consisting of at least two larvae. After the fifth day. the young receive feeds on average about every five minutes, the parents continuing to take breaks as before. For 14 out of the 18 days that the young spend in the nest, they thus consume at least 10,500 larvae, most of which arc harmful to w oodland or gardens.

In the final days, the young always sit and chirp at the entrance hole. Whenever the male or female returns with food, the young birds fr antically clamber over cach other to get at the meal. In 'All-year' nest boxes, where the entrance hole diameter is 3.5 cm, I have sometimes seen three small heads protruding at the same time. Therefore, to shut out other birds and only allow access to blue tits, the entrance hole should only be 2.8 cm in diameter.

When the young leave the nest, their powers of flight are poor, but after only 1.5-2 hours thev can fly exccllcntlv. They continue to be fed by the parents outside the nest box for a while longer, and keep in contact for a full month unless the parents produce a sccond brood. Thereafter thev join up with (locks of tits.

Marsh Tit (Paruspalustris)

Plank nest boxes The marsh til will willingly breed in plank nest boxes made from 2-2.5 cm thick timber. The internal depth should be 19 cm, the diameter of the floor 12 cm, and the entrance hole diameter 3 cm. The floor should be removable to facilitate cleaning. The box should be set 2 3 m from the ground.

In Northern and Eastern Europe the marsh tit often lays two clutches of eggs, and if you have lots of free ground you should set up several nest boxes. The first batch is laid in one nest box and the second in another.

The marsh tit. or to give it its country name, the mouse tit, differs from the willow tit in the not very noticeable black marks on its chin and by the lustre on its black crown. The neck is also a glossy black, the cheeks dirty white, the back grey, and the underside whiteish with grey sides. The male and female arc similar.

The marsh tit nests in tree holes or nest boxes. Nest building starts at the end of April, and is carricd out by the female only. The materials consist of ferns and mosses, straw, wool, and tufts of hair and the lining is made up from feathers, hair, and down. Building normally takes nine days.

The number of eggs varies from five to nine, with only one batch being laid. The female sits alone on the eggs for 13 days without a break, and if she is frightened away at this time, she will not return.

Both the male and female feed the young, and some maintain that the male is content just to deliver the food which he has collected together to the female, who then distributes it to the young. In my experience, both the male and female feed the young directly.

In spring and summer, the diet mainly consists of insect larvae and spiders which arc harmful to the maintenance of woodland, including the eggs and larvae of the pine beauty moth and nun moth, which are among the most feared insects in pine forests. A pair of marsh tits provides food about 500 times per day, and as the eggs of these insects are small, as many as four at a time can sometimes be carricd. Study of a

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single marsh tit showed that during one day it collected 1500 nun moth eggs, as well as other food, to feed its young.

The young are ready to fly after 19 days, and the parents continue to feed them for two weeks after they have left the nest. They stay with the parents for five weeks then join up in flocks with other tits, warblers, and flycatchers.

Most of them are non-migratory in the winter, living in flocks in woodland. Some individuals will venture into areas inhabited by humans to feed on sunflower and hemp seed from seed dispensers. They will take seed in their beaks, fly to a nearby tree and place them in the fork of a branch, where one by one they will squeeze the seeds between their toes, hack away the outer shells, and eat them.

Crested Tit (Par us crisiaiusj

Plank nest boxes The crcstcd tit does not frequently breed in nest boxes. Like its relative the willow tit, it prefers to hack out its own nest hole in the rotten wood tree trunks. However, some individuals will breed in boxes, with a preference for those made from 2.5 cm thick timber or wooden blocks. The internal depth should be 19 cm, the side measurement of the floor at least 12 cm, and the entrance hole 3.2 cm in diameter. The nest box needs to have been hanging up in a natural setting for a least two years before the crested tit will use it. The roof and movable floor should be of hardwood.

The crested tit is smaller than the great tit and has a tuft on its head. The back is brown and the underside grey-white, and the two sexes have a similar appearance. The call is a magniflcant trillingcomprising strings of rolled 'rrrV. In Britain crested tits are only found in a few areas in the Highlands of Scotland such as Speysidc and Glen Affric.

The female starts to build the nest as early as 20th April in Central Sweden. She performs the job alone, producing a soft bed of moss, fern wool, and similar material which insulates well against cold in particular as she lays her eggs early, round about 25th April in Central Sweden, at which time snow can still be lying in drifts.

The nest is finished within five days, after which the female lays one egg per day, to give a total of 4-7 eggs. Brooding lasts for 13 days and is performed by the female only.

Feeding begins as soon as the eggs hatch. The male limits himself to the food he has collected for the female, who then distributes it to the young. The diet consists of pine beauty moth as well as sawfly larvae, leaf

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caterpillar, juniper berries and pine seeds. 'I lie latter two constitute the bulk of the winter diet., when the birds arc living in Hocks.

The young leave the nest after about 20 days and stay with the parents for two weeks, after which lime they join up in flocks with other tits. Crested tits are non-migratory, although the first-year birds tend to disperse from the areas in which they were reared.

Coal til (Parus ater)

Plank nest boxes The coal tit likes a nest box with an internal depth of 20 cm, a floor side measurement of al least 12 cm. and an entrance hole-diameter of 3.5 cm. If there is enough space available set up several of these nest boxes, as the coal lit often lays a second clutch of eggs. Only oncc in the past 29 years have I seen the first and second clutch laid in the same nest box. I .ike other tits, they generally prefer another box in the neighbourhood for the second brood.

'All-year' nest boxes Coal tits have also shown a great liking for the treecrecper model of the "All-year" nest box.

The coal tit is small and short-tailed, with a large while Hash like a half-moon on the neck, white cheeks, and black crown and throat. It looks like a small great tit without the yellow colouring on the breast. The male and female arc similar in appearance.

They breed under tree roots, stones, or old stumps and sometimes in nest boxes. Both sexes join in the nest building, which lakes about one week to complete. The first egg is normally laid at the end of April or in the first days of May. and the final total will vary from five to ten. As with other small birds, one egg is laid each day. The female alone sits on the eggs, for 18 days, during which time the male feeds her with spruce cone seeds.

The young arc fed by both parents, mainly on pine shoot moth and conitcr seeds, about 400 times per day. Or David I .ack oncc made artificial bird mouths from pairs of tweezers and manipulated them from outside the nest to see what coal lit young were given to cat. Fach youngster born in the first brood received on average 69 items of food per day, whereas those born in the second brood received only 59 items on average. Leaf eating larvae dominated the menu. However, this rcscarch was carried out in groves of woodland where deciduous trees were predominant (Lack, 1966).

The young leave the nest after IX days and the female often lays a sccond clutch of eggs straight away, sometimes in the same nest box or

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otherwise in a neighbouring box. The male then takes over the feeding and rearing of the young from the first brood. After 2 4 weeks in the field, the young join up with flocks of tits wandering around the forest. The coal tit is a non-migratory bird.

Winter studies (Lack, 1966) show that 9/10 of the day is spent searching for food, and on average a bird will spend 24 seconds per tree on this task. Hence, each bird will scour over 1000 trees during an 8-hour winter day. The winter diet consists mostly of moth larvae, which overwinter in the outer scales of pine cones into which they have burrowed. The bird therefore has to peck through the thin outer layer of the scales to get to the larvae.

Many coal tits fall victim to severe cold and snow. Winter is easier for them to cope with if you regularly provide them with fat as food in a specific area of the forest throughout the whole of winter and if you make available a well-insulated nest box in this vicinity. I have previously experimented with the string bags one normally fills with nuts and oranges at Christmas. Unfortunately they are easily ripped apart by crows and squirrels, and I have even known foxes to jump up and bite open the bags. Instead you can wrap some plastic-coated chicken wire around the tallow and tic it to the tree trunk with steel wire or very strong cord. The chicken wire must be plastic covered because small birds have exposed skin between the horny toe pads on their feet, and in very severe cold they might become frozen fast to naked wire.

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