The Eurasian Nuthatch – Nesting and Territorial Behaviour
Nuthatches are an important part of our birding life. We watch them in our garden in Portugal, and in Woodcock Wood. They have taken to nest boxes in both places, and we have watched a pair raise young through the intimacy of a nest box camera.
I have recently finished Eric Matthysen’s “The Nuthatches” (1998, Academic Press), a detailed and totally absorbing overview of research on Nuthatch behaviour. The book answered many of the questions that have arisen during our many hours of watching the Nuthatches, and has prompted this extension of my woodlands.co.uk blog written in May 2019.
The original blog was as follows:
“Nuthatches are one of our real favourites. We’ve had them nesting in a box in our walnut tree at home (in Portugal) for several years. They are colourful, noisy and bold birds, full of character, with a bit of a mean streak. They will keep the sparrows and tits under control at a feeder, and even a mated pair don’t tolerate each other too well where food is concerned.
They are able to climb headfirst down a tree, a feat not managed even by the Treecreeper. This agility is evident from an early age. We’ve had the privilege of watching young grow with a nest box camera, and they climb around inside of the box well before their feathers are fully developed. When the young leave the nest they don’t fly immediately, but climb into the upper canopy rather like young Tawny Owls.
Martins and Swallows are often considered to be the potters of the bird world, but Nuthatches also like to mould with mud. They can build elaborate structures at the nest entrance, quickly transforming a hole into a deep tunnel to discourage intruders. Even in winter we’ve seen them continue to add to their construction, filling in gaps and plastering under overhangs.
Although their diet is primarily insects found in the bark of trees, they are partial to seeds (and broken walnuts) and build food caches in times of plenty. The fierce defence of territory and food cache are one and the same. If you provide a constant supply of sunflower seed, they willingly spend hours in a day back and forth to the feeder. The food caches of our Nuthatches must be enormous affairs, much to the benefit of the RSPB shop!
Last autumn (2018) we put up two Nuthatch boxes in Woodcock Wood. Needless to say, the local Woodpeckers were quick to destroy the entrances, and so we fitted metal plates with a 32mm hole.
In early spring a pair of Nuthatches were showing interest. They finally selected a box and began the mud construction. Nesting is now in full swing. Last year in our box at home (in Portugal), six eggs were laid by mid-May, and the young fledged in mid-June. Without the privilege of an in-house video in the Woodcock Wood box we cannot keep an eye on progress, but at the time of writing the male is busy back and forth with grubs and insects.”
(For notes on the relationship between birds that depend on holes and cavities for nesting, and birds that excavate holes see: https://www.woodlands.co.uk/blog/flora-and-fauna/more-on-birds-from-woodcock-wood-better-than-a-hole-in-one/ )
The female takes on all nesting responsibilities, from applying mud to brooding the young.
This year (2020) the Nuthatches in Woodcock Wood have selected another box situated about 50 meters away. I took the above photos of the female beginning to plaster the hole in early March, and in spite of the Covid Virus lockdown we should be able to see how they proceed, as we’ve left a trail camera focused on the box. But not so in Portugal, because of the Covid travel restrictions we are unlikely to see much of the nesting cycle of the pair this year – the pair that have given us such an insight into the antics and private lives of the Eurasian Nuthatch.
Nuthatches in our Portuguese Garden
It was fairly early on in our visits to França (https://woodcockwood.com/about-us-page/) that we first spotted Nuthatches in the garden. But it wasn’t until we were living there for more than a couple of weeks at a time that we put up the feeder, and it was then that the Nuthatches became regular visitors. They are noisy, boisterous and completely unphased by our presence.
Providing a reliable food source of sunflower seeds must have upgraded their territory considerably. They store food in numerous small caches in tree bark crevices throughout their patch, and these ensure food security during the times we and the feeder aren’t around.
In February 2015 we installed a large nest box about 4 meters above the ground in the walnut tree, hoping they might be interested. It seemed extraordinary that the Nuthatches were exploring the box on the same day we put it up. Within a week the female had begun to plaster the entrance with mud, and they have nested in the box until 2019 (see below).
Development of Young Nuthatch – notes from the diary:
Day 23, the day of departure, was as drama filled as any TV soap. At 7.00 on a cold wet evening they started to leave. By the time we had noticed, two had left, and we watched two more depart through a series of bigger and bigger stretches through the hole until finally they are out. They made no attempt to fly, but climbed up the main trunk and disappeared into the foliage.
Two birds remained, and in spite of frequent encouragement from the adults feeding titbits at the entrance, they didn’t budge. The two finally settled down in the box and were brooded by the female for the night. The following day they were fed throughout the day, but spent the next night alone snuggled close together.
On day 25 they received few visits from the adults during the morning. They seemed very quiet and we feared the worst, but just after midday there was a flurry of activity in the box and they both left one after the other, and like the others, climbed the main trunk of the tree into the foliage … and that was the last we saw of them!
The chances are of course that these two were younger than the other four. As we noted in the diary, on the first day we saw chicks in the nest, we counted four gaping beaks, and a couple of days later there were six. These two were probably the runts, and lucky survivors.
We felt privileged to have watched the nesting process in such detail, and were looking forward to comparing notes in 2019. During our stay at the house in February the birds were actively exploring the box, but on our return at the beginning of May the mud structure around the hole had been torn down, presumably by a cat, and the pair had abandoned the box.
They still continued to visit the feeder throughout the year, and had likely found an alternative nesting site. Later in May, Great Tits took over the box and successfully reared 4 young – we watched them instead, but somehow it wasn’t as intriguing!
Nuthatch Territories:
This year (2020) we were in Portugal in February. The Nuthatches were still busy at the feeder but were showing no interest in the box, and with the Covid travel restrictions in place, the chances of us seeing how the nesting saga unfolds is slim. But there is still much to ponder, for instance we have been watching Nuthatches in the garden for the last 5 years, and it’s easy to think of them as “our Nuthatches”, but have we been watching the same birds year on year?
Obviously it is impossible to say, but we know the Nuthatch is fiercely territorial. Their territories are large, averaging between 2 to 3 hectares (5 to 7.5 acres), depending on quality – quality equals food supply, nesting sites, and the number of large mature trees (oaks in particular).
When the young fledge, they leave the parents’ territory by autumn and establish themselves in low quality territories, where they remain until they can replace an adult bird that has died, in a quality territory. The boundaries of quality breeding territories remain fairly constant.
Long term studies of Nuthatch populations (see Matthysen) have shown that only 15% of the birds that hatch make it to become first year breeding adults, 6% make it to the second year, and 3% to the third year.
We can say therefore that “our birds”, having established themselves in our garden in França, could be the same individuals. Theirs is a quality territory, it does contain domestic cats, which we know are a significant problem, but it also has several large walnut trees, a seemingly endless source of sunflower seed, nesting sites, and is edged by oak woodland.
What we don’t know of course is the age of the original birds, and whether, in a sense, our food and nest box provision created a new territory for Nuthatches. The one certainty though is that we will continue to make these provisions to the best of our ability in exchange for an endless source of pleasure.