After the spell of bad weather which scuppered five of our Stonechat nests, we had hoped that the conditions would relent enough to allow the rest of the first brood attempts to succeed. But once again, the weather had other ideas. The spell of bad weather at the end of April (covered in a previous blog) continued, with prolonged northerlies which resulted in more Stonechat broods going down like ninepins.
To sum up our 1st brood totals, we have 15 active territories and 33 chicks were ringed from 7 successful nests. By comparison, 44 chicks were produced from 12 nests for our 1st broods last year. We had 8 failures – 2 from predation, 3 failing on eggs and 3 at the chick stage, so more than a 50% failure rate, which is high for the Bog. While losses to predators are to be expected, the remainder of the failures were most likely down to the bad weather at the wrong time.
Most of our reserve is sheltered from the prevailing south westerly weather, which works in our favour most of the time. However, the entire length of the plateau is exposed to the north, so while we can usually ride out the odd spell of wind and rain from that direction, the fact that the northerlies lasted for a fortnight or more spelled disaster.
The high pressure system might have brought dry, warm weather to most of the country, but here in Norfolk it resulted in strong winds channelling down the North Sea, bringing bitterly cold conditions across the reserve. Inevitably, this suppressed the availability of insect food for both adults and their newly hatched young so the adults must have struggled to find enough food, not only themselves but their chicks. Some nests faced north and were in exposed spots on the plateaux, which can’t have helped.
As the male doesn’t incubate the eggs when the female comes off on a feeding circuit, the eggs are left uncovered. In inclement weather, the female must spend longer and longer off the eggs so eventually they chill too much and become unviable. Or her survival instinct kicks in and she has to abandon the nest in order to find enough food for her own survival.
Unsurprisingly, the pairs which succeeded have all nested in sheltered spots, although one pair was a surprise success. They nested on the ground in an exposed spot in a fairly obvious nest on a north facing slope – we’d have placed bets that it wouldn’t stand a chance but it produced 4 healthy young.
Until we start checking the territories for the second nesting attempts, we also won’t know if we’ve lost any of our females. We did last year during a similar bad weather event when we had a change of several partners, with ‘divorce, remarriage and house moves’ on some territories between the first and second broods.
We also can’t be sure how many of the fledged juveniles have survived the poor weather. Unusually, we’ve not seen many juveniles post-fledging so far. Hopefully, the parents have just taken their youngsters to more sheltered parts of their territories but it’s entirely possible that there have been other casualties, as the first few weeks out of the nest are a very vulnerable time for a small passerine reliant on insect food.
The timing of the bad weather and the length of time it lasted could not have come at a worse time, which is why small passerines play a numbers game and have at least two and sometimes three broods. The warmer weather of the last week or so will hopefully help not only the juveniles survive the first few weeks of life but allow the females to get back into condition again for another nesting attempt.
We’ve also been lucky that all our first brood nesting attempts were early this year. This time last year, we were still finding first brood nests in early to mid-May but all ours had gone down on eggs by mid-April, no doubt helped by the mild weather during March and April. So hopefully there is enough time now for those that failed to try again, hopefully twice. Certainly in previous years, those pairs which failed early went on to nest twice more in a season and mostly successfully.
So fingers crossed that the weather now settles into a warm spring… ready for round two!