This years' nest building got off to a late start probably due to a very cold March. The birds had been using the nest box to roost overnight but on the first bright sunny morning in April the birds started building this seasons nest. First sign was the male bring in nesting material and the female promptly taking it out again!
After a couple of days of adding then removing nesting material nest building began and within a day the pair had filled the box.
After this initial phase it usually takes about 2 weeks of fine tuning and waiting for the trees to start to leaf before egg laying starts. Eggs are usually laid at the rate of one a day and often at exactly the same time each day.
After the female has laid her clutch of eggs she will start incubating them, only leaving the nest for short periods. A mature pair of bluetits will lay between 8-14 eggs, fewer than 8 usually indicates a younger female. The male will visit regularly bringing in food for the female.
The incubation last approximately 2 weeks after which the first eggs will hatch. All the eggs usually hatch within a 48 hour period. Any chicks hatching after this time often find it hard to catch up and compete with larger and stronger siblings.
After all the eggs have hatched it's now three weeks of frantic feeding and growing until the chicks fledge. Any unhatched eggs are rolled to the side of the nest out of harms way. The female will continue to keep the chick warm until they have grown a dark down of their own.
At about 7-10 days all the chicks will have their eyes open and feeding becomes constant and the chicks grow rapidly and become more aggressive to be fed first in the race against time to grow the biggest.
After around 20 days the first of the chicks will fledge, often they will all go on the same day but occasionally one or two are reluctant to leave and the parent birds have to starve them out. There were two such chicks in our 2013 brood who hung around for two days after the first chicks fledged.
Eventually 3 weeks after hatching the final two chicks left the nest.
Key dates for the nesting season:
- Valentines Day (February 14th) clean out your bird box of old nesting material ready for the forthcoming season. Do this in the daytime as you might have birds roosting overnight.
- Birds will visit their old box or investigate a new box daily during February and March, establishing their territory.
- Late March early April nest building begins. Not a strict rule as we have had nest boxes put up in late April early May and succesfully used that season.
- First eggs laid around the time the first leaves appear on the trees.
- Eggs laid at a rate of one a day, usually 8-14 eggs in total.
- Incubation starts after egg laying is complete and lasts approximately 14 days before the first eggs hatch.
- Eggs will hatch within a 48 hour period.
- The chicks will normally fledge 20-21 days after the first eggs hatch, depends on how warm it is and the availability of food.
- Occasionally the adult birds will have a second brood in the same season.