All About Nuthatches

ere is a recent post from the Union Bay Watch Blog published by Larry Hubbell, long-time local photographer and birder.

Sunday, August 9, 2020

Socializing?

Are Downy Woodpeckers social creatures?

A few weeks ago, in the post Social Distancing, we learned about a conflict between a pair of nesting Red-breasted Nuthatches and...

...this determined Downy, who was excavating a new nest in the same dead branch.

From a historical perspective, the Nuthatches had clear ownership. They were re-using, for the third time, a nest which they initially created two years before. In fact, this is the fifth year in a row that Nuthatches have nested in this particular branch.

By May 24th, 2020 the Nuthatches appeared to have finished their annual nesting process. they stopped feeding young in the nest and young bird(s) were seen leaving the nest. Their early finish indicated they made good use of the time saved while not excavating a new 2020 nest.

On the same day, the Downy Woodpecker was still hard at work creating its nest. Oddly, at the same time, the adult Nuthatches began removing an extensive amount of nesting material from their well-used nest. Generally, birds only remove nesting material before nesting. Plus, according to Birds of the World, Red-breasted Nuthatches normally have only one brood a year. Birds of the World mentions just one documented case of a wild pair raising a second brood in the same year (Citation Below).

At the end of the Social Distancing post, which relayed this same information with photos and greater details, we were left with unanswered questions. Would the Nuthatches raise a second set of young in 2020? If so, would the Downy Woodpeckers raise their young at the same time and in the same branch? If both of these things occurred, would the process be peaceful? This week's post will answer some of those questions.

The next day, on May 25th, I saw one of the weathered and worn adults back at the entry to the Nuthatch nest. It was not carrying food for their young, or removing used nesting material, but it also had not abandoned the nest site.

The following day, one of the Woodpeckers was back at their nest site while...

... a Nuthatch was still hanging around at the nest.

On the last day of May, the male Downy still appeared to be working on the nest. Cavity nesters often end up with ruffled feathers on the top of their heads while working on a nest site. 

With cavity-nesting birds, it is difficult to see when incubation begins. Although, researchers have found that with both of these species incubation is often just under two weeks. When we first see the adults bring food to the next we can attempt to reverse calculate egg-laying and attempt to forward calculate fledging - which is two-and-a-half to three weeks from hatching. However, there are many complicating possibilities. All eggs are not laid at the same time. All young may not hatch at the same time. Not all eggs hatch and not all of the young flourish.

Over the next couple of weeks, I often saw quick flights entering and exiting both nests by the respective occupants. However, the birds were too fast for me to catch many photos. Nonetheless, both species exhibited commitment to their nest sites i.e. site fidelity.

On June 10th, I caught a photo of the female Downy stopping by the nest site.

However, a befuddling experience occurred on June 20th. The Red-breasted Nuthatches once again began removing nesting material. 

They were not just cleaning out a few twigs of grass but rather they carried out an extensive removal process...  

 ...with numerous documented trips.

And... 

 ...a considerable amount of energy and effort expended.

 Two days later, the female Downy was seen near her nest. She appeared to be waiting.

On the same day, the male focused on the nest site.

And then, for the first time in nearly a month...

...I photographed a Nuthatch bringing food to the nest!

The next day... 

 ...both adults were present and...

 ...the food deliveries continued.

 There was also obvious activity at the Downy nest.

Their situation became crystal clear when the female was seen bringing food to their nest. This happened on the 23rd of June.

Two days later we can see the feeding continued at the Nuthatch nest, six feet above the Downy nest.

Often the Nuthatches would simply leap out of the nest while keeping their wings folded and without grasping any part of the resin-covered opening.

On the same day, the male Downy secured a somewhat larger prize.

Three days later we can see the Nuthatches were extremely attentive parents. 

Often, one would return with food while its mate was still in the nest feeding the young. 

I was eager to see the feeding process and sometimes uncertain whether the bird in the window was an adult or a youth. However, up to this point, it seemed the returning adult would only offer food to the young - after entering the nest.

 No insect in the surrounding trees was safe.

On the next day, the process appeared to change. Food delivery promptly moved to the self-service window, the young were now capable of getting up and coming to meet the adults.

Downstairs, at the Downy Woodpecker nest, a young bird had reached a similar level of development, on the same day.

The red on the crown most likely indicates this is a young male. Young females usually have little or no red feathers on their crown.

 By the 1st of July, the young Downy was extremely curious about the outside world and...

 ...everything in it.

The wear and tear on the adult Nuthatch's feathers is obvious. Birds of the World suggests molting of the adult's chest feathers was still a couple of weeks away. However, I suspect it is hard to be conclusive about specific birds and their variations in timing.

 I did notice the adult acting as though it was looking for the young in the nest.

Nearby, I noticed a beautiful Nuthatch with fully pristine and clean feathers. 

Initially, I suspected this was one of the young who had just left the nest. If the timing for this bird's fledging is roughly correct then the egg for this bird was laid around the end of May. Which would mean it was laid approximately one week after the first brood left the nest. 

At least one young Downy was being fed in the lower nest on the same day.

The next day, I could still faintly see a Nuthatch in the nest while an adult waited outside.

The Downy feeding continued.

On July 3rd, the upstairs food delivery continued.

 As a matter of fact, food delivery for the Nuthatches continued for a couple of weeks.

Some deliveries looked like seeds and some did not.

The length of the food delivery period seems to indicate this was a good-sized brood.

All About Birds says that Red-breasted Nuthatches can have from two to eight eggs in a clutch.

One of the largest and last food deliveries, I documented, was on July 22nd. If we assume this was the date the last young Nuthatch left the nest then we can estimate the final egg in the clutch was laid around June the ninth. This would mean the female may have laid eight eggs during a ten to twelve day period starting around the end of May. This information fits nicely with the concept of a second brood of Red-breasted Nuthatches.

It is impossible to say whether both broods were 100% successful. Maybe the second brood was compensation for a partial failure of the first. With cavity nesters, it is very difficult to determine the number of young in the nest and almost impossible to be aware of  any changes to the number from day to day. 

For example, in the case of the Downy Woodpeckers I could not prove that they had more than one offspring. I only saw one young at the window at a time. Also, the length of time they spent delivering food to the nest was dramatically less than the Nuthatches. It is curious because Downy Woodpeckers are listed, in All About Birds, as having from three to eight eggs in a clutch.

My observations did not answer all of the questions. However, it appears that both species successfully raised offspring and after the egg-laying stage I did not notice any interactions between the two sets of nesting birds. I would have to admit I did not see any socializing or antagonism between the species. However, sharing the same branch, successful reproduction and mutual co-existence is a fairly mature social solution. It would certainly be wonderful if we, humans, could also learn to co-exist with the lifeforms that surround us. 

This warbler is native to Washington. 

Here are a few more nuthatch photos for those who read to the end.