Blue tit family and Sycamore aphids

I heard the rasping begging calls of blue tit fledglings coming from a Sycamore tree, which I find it is a very common occurrence. As I approached I noticed clouds of Sycamore Aphids cascading down from the tree as the adult Blue tits moved about, searching for the aphids themselves and green caterpillars (above). It was a very impressive spectacle as the light hit the aphids and amplified the effect. The tree leaves were thickly peppered with aphids, and fledglings were having a go at finding food by themselves. One of them found a long green caterpillar and wrestled with it for a while until it was able to swallow it.

I tried to capture the density of aphids flying off around the tree in this photo.

The evenly spaced, winged Sycamore aphids (Drepanosiphum platanoidis)

A fledgling begging for food.

The adult cuts the caterpillar in half before feeding the fledgling.

This young one had caught a caterpillar on its own.

You can watch one of the adults foraging and the aphids flying off here.

Birds and sycamore aphids

Sycamore aphids, Drepanosiphum platanoidis, are Sycamore specialists - and cover your car with honeydew if you happen to park underneath. All adults are winged and sit evenly spaced under leaves. In the spring, sycamores come alive with the calls of hungry Blue Tit fledglings demanding food. It is an easy job for the adults to pick the aphids from under the leaves to feed the chicks (above). Although many leaves have fallen now, there are still some in the sycamores, peppered with the black spots of, Rhytisma acerinum, the tar spot fungus, and some aphids are still in them. In the last few weeks I have seen Great Tits and Chaffinches feeding on them. Today, I watched a chaffinch hovering under the leaves picking the aphids, a most beautiful sight, which unfortunately couldn't catch on my camera.

Food hoarding Coal Tits

One of the things I enjoy the most about watching birds is that even familiar species often surprise me with behaviour I have not seen before. I watched birds feeding on seed and peanut feeders a few days ago. A pair of Coal Tits, Periparus ater, showed their usual energetic prowess: a constant back and forth between the feeders, quickly snatching a seed and then flying away, to return within a few seconds later for another one. This time though, I could see where the Coal Tits were going and they were not flying away from the feeder to eat their seed in solitude, without the hassle of the larger birds, instead, they were storing the seeds: on the ground, pushing the seed into the soil, in the cracks in the pavement, on branches, in a conifer bush or in pots.
 Although corvids are more widely known to store food, food storing is common in Tits (parids). Marsh, Willow and Crested Tits are regular food storers, (although Great and Blue Tits are not). Parids store insects and other invertebrates (after decapitating them), seeds and nuts. They might store hundreds to thousands of items per day, using a different hiding place per item and even covering the hidden item with a piece of bark or stone. They might store the items a short distance away from where they were found, or up to 100 m away. They may often retrieve the food after a few days, but possibly much longer as not readily available food items (such as caterpillars) are often seen consumed by tits in the winter. A Japanese species, the Varied Tit, can feed its nestlings up to 5% of stored seeds from the previous summer-autumn. Parids display good memory not only spatial, to go to the exact place where the food was stored, but also to remember which caches have already been retrieved. Food storing in such small birds might contribute to survival when food is strongly seasonal or unpredictable and it can be retrieved when its consumption will make the largest contribution to survival.
 I managed a very short clip of a Coal Tit storing a seed.


But I wasn't the only one watching. This blue tit was also very interested in the Coal Tits.

After watching it, the Blue Tit came right up to a Coal Tit about to hide a seed - it is just visible in its beak in the photo below. After a brief hesitation, the Coal Tit decided to go somewhere else and left just after I took the following shot. Sorry about picture quality today, but all the shots were taken through glass.

More information
David F Sherry (1989). Food storing in the Paridae Wilson Bulletin, 101 (2), 289-304

Fledglings galore

The resident birds seem to have synchronised their breeding to such extent that I saw/heard seven different species of fledglings or chicks in my way to work. A Blackbird (#1) fledgling gave a try to hunt for itself, its parents out of sight. It was hilarious to watch it picking up a dried berry and dropping it and listening for worms.

A lovely fluffy Robin (#2) fledgling by the university parking lot, still very naive, let me get quite close (top photo), a pair of Greenfinches landed next to it and had me confused for a while!

Then a pair of noisy rook (#3) youngsters by the university woodland area demanded to be fed, I could only get a poor shot.

The family of Wrens (#4) I pictured a couple of posts ago were still around, the young giving their calls from a bed of nettles and docks opposite the Wilberforce building.

In my way back from work, a lovely family of Long Tailed Tits (#5) 'see-see-seeing', but the young ones shun me and only gave me their tails to photograph.

In my kids school, the Blue Tit (#6) eggs have finally hatched and I watched the live footage, with one of the parents sitting on very hungry and bare chicks

Near home, the Starling (#7) adults and youngsters in the nest have starting calling to each other with their 'churrr' calls which mean that they are almost ready to leave their nests.

The bumblebee tit

Today I watched a pair of Blue Tits paying a lot of attention to the inflorescences of Mahonia in the local park, coming back to them again and again. What were they doing? If you hear nectar feeding in birds you would most likely think on hummingbirds and the tropics. However, several bird groups feed regularly on nectar in addition to hummingbirds, honeyeaters and sunbirds. In Australia, birds are actually the main flower pollinators. Although nectar feeding behaviour in Europe is far less widespread, it does happen. In 1985, Hugh Ford reviewed the handful of studies suggesting or indicating nectarivory in European birds (see table below).

 Most of the species were warblers, with the Chiffchaff and the Black-cap the most cited ones. Warblers winter in southern Europe or Africa, where there is a larger proportion of bird-pollinated flowers and where nectar feeding in birds, is more widespread. They are also known to exploit nectar while migrating, as a quick way to gain energy. The bird species that most commonly feeds on nectar in northern Europe, however, is - you guessed it - the versatile Blue Tit. Blue Tits seen on flowers are often thought to be foraging for insects, or feeding on parts of the plant, such as petals. However, Blue tits have been recorded feeding on a range of flowers, both introduced garden varieties and native ones: Gooseberries, Flowering currants, and the Fritillary Imperial Crown. What is more, Fitzpatrick, studying suburban blue tits, found that nectar can make a substantial part of Blue tit diet in early spring. Feeding on flowering currant inflorescences, Blue tits chose the most productive flowers, those with a darker pink rim. They used two strategies to get at the nectar: pecking the corolla out to reach the nectaries, or perforating a hole on the side of the flower - bumblebee style - to reach the nectar directly, as the flowers are too narrow for them to insert their beaks, and therefore cause quite a deal of flower destruction. Coal Tits were also observed feeding on the Flowering Currants, but they inserted their more slender beak into the flower and thus did not destroy the flower in the process of feeding.
   The Fritillary imperial crown is an impressive red or yellow flowered bulb in which a whorl of wide, flowers hang from a stout bare stem. It originates from Asia but is widely planted in the UK. Búrquez, showed that Blue tits not only collect nectar from these flowers, but they also act as are efficient pollinators of the plant.

  Blue tits in native habitats are often seen feeding on willow blossom, so nectar feeding seems to be another of the wide variety of opportunistic behaviours used by this tit to use resources.

More information
Ford, H. (1985). Nectarivory and Pollination by Birds in Southern Australia and Europe Oikos, 44 (1) DOI: 10.2307/3544053

Búrquez, A. (1989). Blue Tits, Parus caeruleus, as Pollinators of the Crown Imperial, Fritillaria imperialis, in Britain Oikos, 55 (3) DOI: 10.2307/3565592

Fitzpatrick, S. (1994). Nectar-feeding by suburban Blue Tits: contribution to the diet in spring Bird Study, 41 (2), 136-145 DOI: 10.1080/00063659409477210