Red knots breed in the Arctic region, where climate change is three times faster than elsewhere in the world. Not only is climate change more pronounced at these latitudes, also the breeding season for birds is much shorter, only two months, and it is therefore crucial for the migratory red knot, wintering at subtropical latitudes, to be at the right time at the right place. In the past, red knots arrived before the snow melted and laid their eggs on scarce snow-free patches, to perfectly time the hatching of the eggs with the time of emerging insects from the soil (food peak) after the snow has melted. Nowadays, with earlier snow melts, red knots are troubled to arrive at the right time at their breeding grounds and their chicks might hatch later than the time of emerging insects from the soil (phenological mismatch). Questions on date upon arrival at the breeding grounds and growth and survival of the chicks were risen. Already in 2016, van Gils et al. published in Science that the red knot became 20% smaller in comparison to 30 years ago and suggested that this might due to the phenological mismatch they experienced as a chick induced by climate change. Therefore, in this expedition we will focus on measuring the diet and the effect of (limited) diet due to the mismatch with the food peak in red knot chicks. A big adventure lies ahead of us!

~~ all blogs by Clazina Kwakernaak, scroll down for earlier posts ~~

Tuesday 14 June | Back to N(h)ome!

Distribution of the hatch dates. Data collected by Jim Johnson

According to hatching data from the previous years, 15th of June would be the peak date of hatching chicks! Therefore, Jeroen and I went back to Nome to prepare everything for the foraging experiment and to be able to care for the -soon-to-arrive eggs or chicks. With the arrival of Jim Johnson (red knot researcher) at camp, it was time to perform the daily “chick sweeps”, next to tracking the radio-tagged birds and droning. During the ‘chick sweep’ method, the team walks on a line, and one will be playing the begging chick sound, trying to lure the male, allowing to rest of the team find the chicks and catch them. (NB prior to hatching, the female migrates to the wintering area (Mexico) thereby leaving the male to take care of the chicks.)

The experimental set-up. Photo: Clazina Kwakernaak

Tuesday 7 of June | Off the grid

Overview of the camp. Photo: Clazina Kwakernaak

Upon the arrival of Zak Pohlen (wildlife biologist) and Kelsi Hunt (research associate), it was time to set up camp at 34 miles! From now, we wake up surrounded by singing red knots in the middle of our study area. Because we were running out of methods to catch male red knots (since they didn’t respond to the sound of the singing male sound anymore) we discovered that some males already respond to the sound of begging chicks. The sound of the begging chick is usually used to catch the male when he already has chicks. Since we needed the nest prior to hatching, we used the begging chick sound and decoy chick instead of the singing male and decoy adult to catch males and after 2 weeks we finally managed to catch 5 males in total and deployed them with a radio tag.  

Unfortunately, when tracking the radio-tagged birds we found out that these birds were rather late, and the eggs would hatch too late to be useful for the foraging experiment.

Moreover, over time it became silently clear that we saw less and less red knots, meaning that the incubation period had already started and that observing pairs to find nests wouldn’t work anymore. Therefore, we rely on the drone to detect nest for us! Because our methods are quite time consuming, we needed an extra hand to fly the drone, and luckily Simon Spriensma (drone pilot) was more than happy to join to help us out! With some finetuning of the fly and detection software, Simon is eager to find us some nests!

Detecting a red knot brood with the infra-red drone. Movie: Simon Spriensma.

Tuesday 7 June 2022 |  First nest

The first nest was found by Clazina!!! Photo: Clazina Kwakernaak After inspecting this hill thoroughly we found the nest close to the remaining snowpatch. Photo: Jan van Gils

Sunday 5 June 2022 | You can’t always catch what you want

But we tried so hard, to find, and got what we almost needed.

Looking for scrapes. Photo: Jeroen Reneerkens

The last few days, we worked hard to catch males using the so-called “sound-and-decoy method”. In total we were able to catch three males and deployed them with a radio tag! Unfortunately, the window of opportunity to catch males before the egg laying phase is now over. Ideally, we would have caught at least four males which would give us 4 nests to take 2 eggs from for the chick foraging experiment later in the season. Therefore, we switched towards the so-called “observation method”, in which we observed paired knots hopefully leading us to their nest. Both Jeroen and I found a copulating pair but weren’t yet successful to find the nest. Nonetheless, we found a lot of scrapes (nest building) which we mapped and will check periodically. These scrapes only lead ~5% of the time to a nest. Because the summer progresses rapidly and the snow melts fast, we need to act fast on the behaviour of the birds and soon we will use the drone to find nests during the incubation period.

:  Jan and Jeroen walking through the last snow patch. Photo: Tim Oortwijn

Tuesday 1 of June | June fools

The past couple of days, we tried to map territories of singing male knots, with the aim to catch these birds and give them a radio-tag (which later enables us to find their nest). While doing so and wandering around on my own, I saw an American golden plover and my first thought was, does it have a broken wing? But it fooled me, it was the broken wing display, which is typically to lure “people” away from the nest.

American Golden plover on its nest. Photo: Clazina Kwakernaak American Golden plover nest. Photo: Clazina Kwakernaak

Nevertheless, we found the nest - the first nest of the season! Although it was not a red knot nest, we nevertheless could use it to calibrate the infra-red drone!  Flying to the nest with the drone, the bird flew away and we could detect warm eggs. Red knots may behave differently and will most likely stay on the nest. It will still be challenging, but at the same time it looks promising!

Using the drone for calibration. Photo: Clazina Kwakernaak Detecting the nest (yellow dot) with the drone. Photo: Jan van Gils

Friday 27 May 2022 | Time to catch them all

A pitfall to trap insects. Photo: Jan van Gils

The past few days were catching days! Together with placing pitfalls, traps in the ground to catch insects, we walked around the study area in search of more red knots. Since there is still a lot of snow, we were not yet able to place all the pitfalls at locations set-up in 2016. In order to catch a red knot, we searched for singing males, females do not sing. The woosh net was set up after we found a male and placed a 3D printed red knot together with a MP3 repeating the song of the red knot in front of the net. Usually, the song of the red knot attracts a male which is looking for the intruder of his territory. Sometimes males are shy, and it takes a lot of time before it comes close to the decoy, whereas others already inspect the decoy after three minutes!

Catching a male red knot with a woosh net. Video: Clazina Kwakernaak

When the male came close to the decoy, Jeroen triggered the woosh net, trapping the red knot. After a male was caught, it was ringed, measured and a radio tag was glued to its back. The radio tag is important for finding the bird back later when it settles with a female and starts to breed. This is a novel method for finding nests enabling us to catch as much as possible.

Releasing the male after measuring with a radio tag. Video: Clazina Kwakernaak

Monday 23 May 2022 | Arrival in Nome

Arrival in Nome. Photo: Jan van Gils

At 8:00 AM, we took off to Nome, our destination! Upon arrival, we first dropped off all our stuff at the apartment where the chick experiment will take place. It was finally time to check out our study areas 34 miles and 37 miles to see how the snow coverage would be. During the ride, we already saw typical breeding birds of the area but no red knot yet.

The Dutch team at the study area 34 miles (Jeroen, Clazina, Jan, Tim and Job). Photo: Jim Johnson : Walking around the study area. Photo: Clazina Kwakernaak

Arriving at 34 miles, we walked towards the place where we were planning to set-up camp and concluded that it still too wet and too much snow for probably another 10 days. Nevertheless, we had a beautiful walk with our eyes and ears open hoping to spot a red knot around the study areas! And indeed, Job spotted our first red knot, and Jim spotted three, opening our fieldwork season!

The first red knot! Photo: Job ten Horn

Sunday, 22 May 2022 | Preparation day

After a well-deserved night of sleep, it is time to prepare everything for when we leave to our destination Nome! 

The infra-red drone with an additional RGB camera. Photo: Clazina Kwakernaak

We took our infra-red drone for a test-flight since we were still in an area with proper network reception.  The use of infra-red drones to detect nests is becoming increasingly popular and has been mostly used to detect meadow bird nest in early mornings. At that time, the difference is the highest between the ground temperature and body temperature of the meadow birds. However, in the absence of night-time, it is much harder to detect nests with the use of infra-red on the Arctic tundra. Therefore, our team are the first to try to detect red knot nests on the tundra with the use of an infra-red drone in combination with an additional RGB camera.

Test-flight of the drone. Video: Clazina Kwakernaak

Jan helping the drone to land at the controller Job and Tim. Video: Clazina Kwakernaak

Afterwards it was time to construct arenas (~4m2) from the wood which we had collected the day before. The arenas will function as a foraging area for an experiment with red knot chicks. In those foraging arenas, red knot chicks will randomly receive different densities of food at different ages to measure their intake rate and energy expenditure, measuring the functional response. The last and most important preparation of course was getting groceries!

View from the airplane. Melting sea ice around Greenland. . Photo: Clazina Kwakernaak

Saturday 21 May 2022 | Departure day 

It is 5:00 AM, we are fully packed and ready to go to Schiphol to start our migration towards Anchorage. Everybody had a seat located at the window and it was totally worth it! We flew northward over Greenland and the view was stunning with the melting sea ice and just before Anchorage we passed the highest mountain of Northern America, Mount McKinley (6,190 m).

View from the airplane. Flying past Mount McKinley. Photo Clazina Kwakernaak Photo: Clazina Kwakernaak

With quite some delay between the transfers we arrived at Anchorage, after 13 hours, around 1:15 PM local time. We were warmly welcomed by the red knot researcher and our host Jim Johnson, and by the famous Bald eagle, which was the first bird we saw! After dropping off our luggage, it was time to already do some shopping for the preparations for the next day. No rest for the researchers! However, it is not bad at all because in between the shopping we enjoyed the warm (± 14oC) and sunny weather! After the majority of the shopping was done, we met the lovely family of Jim Johnson, had a delicious dinner and after being awake for 26 hours it was finally time to sleep.

Loading the truck (left: Job ten Horn, middle: Jim Johnson, right: Jeroen Reneerkens) with preparation materials. Photo: Jan van Gils. The lovely view from the house of Jim Johnson. Photo: Clazina Kwakernaak