For the last few months, we, and millions of others, have been enchanted by a pair of blue tits captured on a live nest cam building their nest, brooding a clutch of eggs, and rearing their chicks.
The birds moved into a nest box fitted with a camera in Loughborough in March, and the resulting videos have been posted to a dedicated YouTube channel.
Although 8 eggs hatched, and the parents had to deal with predators including a cat and larger birds attempting to raid the nest box, sadly only 2 chicks made it. The owner of the bird box suggested that this was due to a cold snap during the nesting period, and because the chicks took 4 days to hatch rather than the usual 2 which meant that that the last chicks were much smaller than their siblings who had already been fed for a couple of days.
We watched in awe as the parents removed their dead babies from the nest, fed caterpillars to the remaining hungry pair, and carried away poo to keep the nest clean.
The chicks have now fledged and taken their first flight, and a 21 minute highlight reel has just been posted that shows all the action over 21 days from the first egg hatching to the chicks leaving the nest.
Blue tits are one of the most common birds to use nest boxes in gardens, parks, and woodlands. In the wild, they nest in small cavities such as a hole in a tree, a crack in a wall, or an old woodpecker’s nest. They’ve also been known to set up home in some unusual places such as lampposts, cigarette butt bins, and hanging baskets.
A standard, closed box with an entrance hole of 25 mm is best for the species, and although they may use a box with a larger hole, they run the risk of being ousted by larger birds such as great tits.
They begin searching for a suitable site in February, so if you want to encourage blue tits to nest in your garden get your boxes up nice and early, preferably in the previous autumn. Make sure there is a clear flight path to the entrance hole, and that it can’t be easily accessed by predators. Hang up a few feeders filled with high energy foods such as peanuts, sunflower hearts, and suet, to help them get ready for the hard work ahead.
Once they’ve found the perfect spot, the female blue tit will spend about 2 weeks crafting a cup-shaped nest from moss and lining it with feathers, fur, or wool.
Blue tits lay between 8 and 10 eggs, laying one egg a day usually first thing in the morning. Before she starts laying, the female will pluck feathers from her breast to create a bare patch, known as the ‘brood patch’ to help her keep the eggs warm while she incubates them for between 13 and 15 days. If you see her leave the nest for a few minutes during this period, don’t worry as although her mate will feed her during incubation, she will also leave the nest to search for food herself.
Try not to get too close to the nest box or disturb it in any way. Not only would you be breaking the law, you may also spook the birds who could abandon the nest if they think you’re a threat. If you want to see what’s going on inside, the best thing to do is get yourself a nest cam or all-in-one camera nest box so you can stream pictures to your TV or laptop.
The footage of the blue tits in Loughborough was captured with a Green Feathers wireless camera, which is specially designed to sit inside a nest box and includes night vision and a wide-angle lens so you can see the entire nest as well as birds entering and leaving the box.
When the chicks hatch, they are naked and blind and extremely vulnerable. Both parents feed the chicks caterpillars, which is an arduous task as each tiny bird can eat up to 100 caterpillars a day. It is not unusual for a parent to feed the chicks at a rate of one feed every 90 seconds during the height of breeding season.
In a particularly cold or wet spring, finding enough caterpillars to ensure the chicks survive can be hard and it is getting harder due to climate change. On average, spring is arriving earlier which means trees’ leaves which provide food for caterpillars are opening earlier. This means the population of caterpillars is also peaking earlier, and although blue tits have started to breed earlier to compensate, they haven’t shifted enough to keep up with the peak abundance of caterpillars.
It’s not just blue tits that are affected by this change. Research has shown that great tits are also struggling to find enough food for their chicks, and pied flycatchers, which are migratory birds and not in the UK for the winter, are much less able to respond to the warmer spring weather.
Blue tits can be aggressive when defending the nest, hissing and bunting at intruders, which has earned them the nickname ‘Billy Biter’. A study published in the journal Behavioural Ecology and Sociology, showed that this may be due to Batesian mimicry, in which harmless species protect themselves from predators by mimicking more dangerous species.
To test the theory, a team of French researchers compared the acoustic similarity of the hissing sound produced by a female blue tit with the hisses of three species of snake who lived in the same habitat.
They then exposed house mice who had never encountered blue tits or snakes to the hissing sounds. House mice were chosen because they are preyed upon by snakes and because they compete with blue tits for nesting sites and prey upon their eggs
The scientists found that the hisses the blue tit produced when defending her nest, were very similar to the snakes’ hisses. They also found that the house mice showed similar levels of anxiety in response, compared to control sounds.
However, the team acknowledge that there may be another explanation. Hissing is widely used by vertebrates in threatening situations so it may simply be a conserved behaviour used by both snakes and blue tits. More research is required to find out if the Batesian mimicry hypothesis holds true.
Like many garden birds, blue tits have a low juvenile survival rate – this is the reason they lay so many eggs. Just 38% reach their first year, and although birds have been found in the wild reaching ages of 10 years, the average lifespan is only 3 years. This means that each bird has just a couple of chances to pass their genes on to the next generation.
With natural nesting sites disappearing, providing a safe, secure nest box in your garden can help these pretty little birds survive.
