The Eurasian Nuthatch – Nesting and Territorial Behaviour

Nuthatches have become an important part of our birdwatching experiences. We regularly see them in our garden in Portugal as well as in Woodcock Wood. They have accepted nest boxes in both locations, and using a nest box camera, we have even been able to watch a pair raise their young at remarkably close range.

I recently completed Eric Matthysen’s 1998 book The Nuthatches, published by Academic Press. It provides a detailed and absorbing account of research into Nuthatch behaviour. The book answered many of the questions that developed during our countless hours of observing these birds and inspired me to expand on a blog I originally wrote for woodlands.co.uk in May 2019.

Why We Find Nuthatches So Fascinating

Nuthatches have long been among our favourite birds. For several years, a pair nested in a box attached to the walnut tree at our home in Portugal. They are colourful, energetic, noisy and remarkably confident birds, with plenty of personality and even a slightly aggressive side. At feeding stations, they are capable of keeping sparrows and tits at a distance, and even a bonded pair may not be especially tolerant of one another when food is involved.

Their climbing ability is particularly impressive. Nuthatches can move headfirst down the trunks of trees, something even Treecreepers cannot accomplish. This remarkable agility appears very early in life. Through a nest box camera, we were able to observe young birds moving around inside the box before their feathers had completely developed.

When the young finally leave the nest, they do not immediately take flight. Instead, they climb upward into the tree canopy, behaving in a way that is somewhat reminiscent of young Tawny Owls.

Building With Mud

Martins and Swallows are often described as the great mud-builders among birds, but Nuthatches are also remarkably skilled at using mud. They can create complicated structures around the entrance of a nest cavity, rapidly turning an opening into a narrower, deeper passage that can make it more difficult for intruders to enter.

Their building activity does not necessarily stop once winter arrives. We have observed Nuthatches continuing to work on their constructions during the colder months, filling openings and spreading mud beneath overhanging sections.

Feeding and Food Storage

Although insects found among tree bark form an important part of their diet, Nuthatches also enjoy seeds and pieces of walnut. When food is abundant, they create numerous food stores for later use.

Their strong defence of feeding areas and their food caches are closely connected. When a steady supply of sunflower seeds is available, Nuthatches can spend many hours traveling repeatedly between the feeder and their territory.

The number of hidden food stores made by the Nuthatches in our area must be considerable, especially given how frequently they visit the feeder.

Establishing a Nest in Woodcock Wood

In autumn 2018, we installed two Nuthatch nest boxes in Woodcock Wood. The local Woodpeckers quickly damaged the entrances, so we added metal plates with 32 mm openings to protect them.

By early spring, a pair of Nuthatches had begun showing interest in the boxes. Eventually they chose one and started applying mud around the entrance.

The nesting process soon became fully established. At our home in Portugal the previous year, six eggs had been laid by the middle of May, with the young leaving the nest around the middle of June. Without an indoor video camera in the Woodcock Wood box, we could not observe every stage of the process, but the male was clearly busy making repeated trips to the nest with grubs and insects.

The Female’s Role in Nesting

The female takes responsibility for essentially all of the nest-building and incubation duties, including applying mud to the entrance and brooding the young.

In 2020, the Nuthatches in Woodcock Wood selected another box approximately 50 metres from the previous one. In early March, I photographed the female beginning to cover the entrance with mud.

Despite the restrictions caused by the Covid virus lockdown, we hoped to follow their progress because a trail camera had been positioned to monitor the box. Our observations in Portugal were less certain that year, however, because Covid-related travel restrictions made it unlikely that we would be able to witness much of the nesting cycle of the pair that had previously given us such an extraordinary insight into the private lives and behaviour of Eurasian Nuthatches.

Nuthatches in Our Portuguese Garden

We first noticed Nuthatches relatively early during our visits to França. However, it was not until we began staying there for more than a couple of weeks at a time that we installed a bird feeder. Once the feeder was in place, the Nuthatches became regular visitors.

They are remarkably noisy, energetic and confident birds and appear largely unconcerned by our presence.

Providing a dependable supply of sunflower seeds seems to have made the territory particularly attractive. The birds hide food in numerous small crevices in tree bark throughout their range, creating reserves that help them survive during periods when we are away and the feeder is no longer being replenished.

Installing the Portuguese Nest Box

In February 2015, we placed a large nest box approximately four metres above the ground in our walnut tree, hoping that the Nuthatches might use it.

Their response was astonishingly quick. They began investigating the box on the very day it was installed. Within a week, the female had started covering the entrance with mud.

The pair continued to use the box for nesting through 2019.

Watching the Young Leave the Nest

The 23rd day, which turned out to be the day the young left the nest, was filled with drama.

At around 7:00 on a cold and wet evening, the young began making their way out. By the time we realized what was happening, two had already departed. We then watched another two gradually work their way through the opening, stretching farther and farther until they finally managed to emerge.

None of them attempted to fly. Instead, they climbed directly up the main trunk and disappeared into the foliage.

Two young birds remained inside. Despite repeated encouragement from the adults, who brought small pieces of food to the entrance, these two refused to leave. Eventually they settled inside the box, where the female brooded them through the night.

The following day, the adults continued bringing them food throughout the day. That night, however, the two young birds were left by themselves, sitting closely together inside the box.

The Final Two Chicks

On day 25, the adults made very few visits during the morning. The young birds were unusually quiet, which made us worry that something had gone wrong.

Shortly after midday, however, activity suddenly increased inside the box. One after the other, both remaining young birds finally emerged. Just like the others, they climbed up the tree trunk and disappeared into the foliage.

That was the last time we saw them.

It is likely that these two chicks were younger than the other four. When we first noticed the chicks in the nest, we counted four open mouths, while two days later there were six. The final two were probably the smallest members of the brood, yet they had managed to survive.

We felt extremely fortunate to have been able to observe the nesting process in such detail and looked forward to comparing our observations the following year.

The Nest Box Is Abandoned

During our stay at the house in February, the Nuthatches were actively investigating the nest box. However, when we returned at the beginning of May, the mud construction surrounding the entrance had been destroyed, apparently by a cat.

The pair had abandoned the box.

They nevertheless continued visiting the feeder throughout the year, suggesting that they had probably established another nesting location elsewhere.

Later in May, Great Tits moved into the abandoned box and successfully raised four young. We watched their progress instead, although somehow their nesting behaviour did not capture our attention in quite the same way as the Nuthatches.

Nuthatch Territories

In February 2020, we were again in Portugal. The Nuthatches remained busy visiting the feeder but showed no interest in the nest box. With Covid travel restrictions still in place, it seemed unlikely that we would be able to observe how their nesting activities developed that year.

Their behaviour nevertheless raised an interesting question. We had been watching Nuthatches in our garden for approximately five years, and it was easy to think of them as “our Nuthatches.” But were we actually seeing the same individuals year after year?

There is no definite way for us to know. What is clear, however, is that Nuthatches are strongly territorial.

A typical territory covers approximately 2 to 3 hectares, or about 5 to 7.5 acres, although the size and quality of territories vary. Territory quality depends on several factors, including the availability of food, suitable nesting locations, and large mature trees, particularly oaks.

What Happens to Young Nuthatches?

Once young Nuthatches become independent, they leave their parents’ territory by autumn. They generally establish themselves in lower-quality territories and remain there until an adult bird dies and a better territory becomes available.

The boundaries of high-quality breeding territories tend to remain relatively stable over time.

Long-term research into Nuthatch populations, including the studies discussed by Matthysen, has shown how difficult it is for young birds to survive to breeding age. Only about 15% of birds that hatch survive to become breeding adults in their first year. Approximately 6% survive to their second year, while only around 3% make it to their third year.

Are They the Same Nuthatches?

Based on these survival patterns, it is possible that the Nuthatches that established themselves in our garden at França could indeed include the same individuals we have watched over the years.

Their territory appears to be a high-quality one. It does contain domestic cats, which are known to present a significant danger to birds, but it also offers several large walnut trees, a seemingly endless supply of sunflower seeds, suitable nesting opportunities, and a surrounding area bordered by oak woodland.

There are still many things we cannot determine. We do not know the ages of the original birds, nor can we say whether our provision of food and a nest box effectively helped create a new territory for Nuthatches.

One thing is certain, however: we will continue providing food, nesting opportunities and suitable support for these remarkable birds as far as we can. In return, they provide us with an almost endless source of fascination and pleasure.