Tits make excellent study species for ecological research as they readily take to nest boxes, breed at high densities, do not travel far from where they are born, and cope well with being monitored by scientists. This means we can individually tag large numbers of nestlings (with unique leg rings) and follow them throughout their lifetimes allowing us to answer questions such as: Do birds age? To what extent are individual differences in how a bird looks or how it behaves inherited from parents to offspring? Are tits able to track climate change, and if so how is this achieved? Do birds learn new skills from each other, and does this depend on how sociable they are? To learn more about our research click here.
The Breeding Season
During early spring, pairs of tits split from their winter flocks and begin defending territories ready to breed. The female will select a nest site and construct a nest (built mainly from moss, animal hair and feathers). Once she begins laying she will produce one egg a day for 8-10 days and then incubate her clutch for approximately 13 days. Throughout incubation, the male will visit the female regularly to bring her food.
Once the chicks hatch, parents embark on what is perhaps the most challenging few weeks of their lives – in the space of two weeks they will transform their naked and blind chicks, weighing about 1 gram each, into fully-formed birds capable to flight, each weighing more than their parents! This is only possible because the parents time their breeding so that they have chicks in the nest when there are lots of caterpillars in the woods. Although caterpillars are plentiful, they are only available to the tit for a few weeks, and the timing of this caterpillar peak varies greatly between years. Timing of egg laying is therefore crucial - if parents get it wrong, and lay too early or too late, they may not be able to find enough food to keep their brood alive. To learn more about our work exploring how birds time their breeding and the consequences of these decisions click here.
If the young survive the nestling period, they will leave the nest when they are about three weeks old and travel around with their parents for several more weeks before becoming independent.
Autumn & Winter
Between late spring and autumn, fledglings will move about 400-900 metres from their birth site, where they then form mixed species flocks. As the weather gets cooler and insect food becomes more scarce, the tit switch to feeding on nuts and seeds.
In Wytham, we individually tag all nestlings and adult tits with two unique leg rings - a standard metal BTO ring and a plastic ring containing an RFID tag (similar to those fitted to pet dogs). This means that every time we catch a bird we know who it is and its history (e.g. where it was born, where it has bred, and the identity of its parents, siblings and offspring). The RFID tags can be read remotely, meaning that we don't need to catch birds to know where they are; during the winter we put out a grid of bird feeders across the woods with RFID tag readers that detect every tagged bird that comes to feed (see video below). This not only tells us whether a bird is in the woods, but also how it forages and uses space, and which other birds it spends its time with. To learn more about our research into the winter movements and social behaviour click here.