Tromsø's Kittiwalkers: the mid-summer report.

Midway through the breeding season, we’re sharing an update based on the dedicated efforts of the Kittiwalkers.

Two Kittiwalkers are monitoring kittiwake hotels in Tromsø city center.

For the third year in a row, the Kittiwalkers are monitoring the number of adults, nests, and chicks across Tromsø city center. Their observations help understand how kittiwakes use the city for nesting and monitor the general wellbeing of the kittiwake population in Tromsø. Rissa Citizen Science uses these precious observations to keep Tromsø Municipality and other stakeholders informed, to blow the whistle when necessary and suggest solutions that support safe nesting while reducing disturbance.

In this article, we look at the Kittiwalkers engagement, how kittiwakes are doing this year, and how changes in the city have affected their breeding success.

This update is based on data collected up to July 7^th 2025.

Kittiwalker counting kittiwakes on Pellerin's buildings in Tromsø in June 2025.

Kittiwalkers' engagement

Our community of kittiwake advocates has grown stronger every year—and it shows! With 30 active users on the new Rissa Citizen Science app, we’ve already logged more submissions than in all of 2023 and 2024 combined. This rise is partly due to an earlier monitoring start, more participants, and stronger overall engagement.

Number of submissions on the Rissa Citizen Science's app for the hotels and the city stations.

What is the difference between a station and a hotel?

City stations: A "station" refers to a location with one or more kittiwake nests, typically a building where nests are found on window ledges, rooftops, or signs. Some stations become inactive when buildings are demolished or deterrents are installed to prevent nesting. New stations emerge when kittiwakes begin using previously unoccupied buildings.

Kittiwake hotels: These structures are designed to attract kittiwakes and provide safe nesting conditions away from buildings, helping reduce nuisance. In addition to easing conflicts and supporting coexistence, they also serve as partial compensation for the widespread destruction of nests across Tromsø.

Mapping kittiwake nests

The map below shows how the stations changed between 2024 and 2025, as a consequence of deterrents being deployed or a building being demolished or successful kittiwake hotels being dismantled.

Map of the kittiwake hotels and stations in 2024 and 2025 in Tromsø city center.

• Deterrents

16 stations have been equipped with deterrents since last year’s breeding season.

Out of these, 6 were fully abandoned this year as a consequence.

Kittiwakes returned to the 10 others, but in fewer numbers.

One example is the Full Steam Restaurant, a building owned by Pellerin AS, who deployed electric fences on the roof in winter 2024-25: 27 nests were recorded by the 7th of June this year, compared to 36 last year.

Kittiwalker surveying Pellerin's building covered in anti-kittiwake electric fences.

• Demolition

The new stations in the south of the city are likely a result of the demolition of two important sites that previously hosted the largest colonies in Tromsø: the Mack Øst building and two kittiwake hotels at Strandvegen 8. Together, these sites hosted over 250 nests in 2024.

Two new kittiwake hotels were put up as compensation for the demolition of the Mack Øst building, but with limited success due to reasons explained in a previous article. Only 2 nests were present on the 8th of July as we write this article.

Kittiwake nesting on the Mack Øst kittiwake hotel in spring 2025.

City stations

So far, the total number of adults observed in the city center is much higher than in 2024, while the number of nests only slightly increased.

However, this does not reflect the exact growth of the kittiwake population in Tromsø, as the Mack Øst colony and the two kittiwake hotels at Strandvegen 8 (about 250 pairs combined) were not included in the Kittiwalkers' monitoring in 2024.

Kittiwake adults and nests in Tromsø city in 2024 and 2025.

The observed increase in adult birds, along with the emergence of new nesting stations (map above), suggests that kittiwakes displaced from Mack Øst and Strandvegen 8 have likely relocated to multiple alternative nearby buildings. This dispersal pattern underscores the urgency of addressing conflict mitigation as a key management priority.

The modest increase in nest numbers, compared to the significant rise in adult birds, may partly reflect the stress kittiwakes experience when forced to relocate after the destruction of their previous colonies. For instance, many kittiwakes at Strandvegen 8 remained on the rooftop for extended periods without nesting. Some eventually moved to new locations, but did so late in the season, with limited reproductive success.

The observed decrease in adult kittiwakes after June 15 could be attributed to individuals giving up on breeding and spending more time at sea.

Kittiwakes relocating to Strandvegen 8, after the destruction of their former colony.

Kittiwake hotels

The ratio of occupied nests to available nesting spaces is used as an indicator of each hotel’s success. As illustrated in the figure below, this ratio varies significantly between hotels.

Occupancy rate and number of nests on the kittiwake hotels in Tromsø, on the 7th of July 2025.

Hotel 3 (green, Muséparken) shows the strongest performance: 28 nests were in use out of 46 available nest spaces as of July 7th, 2025.

Hotels 8 and 9 (Fylkeshuset) are doing better this year. They weren’t used at all last season, but raising their height seems have made them much more appealing to the kittiwakes.

About Hotel 5 (mega hotel, Muséparken), which was put up at the start of 2025, only the upper floor is being used by kittiwakes this year. For hotels 6 and 7 (Mack Øst hotels), we invite you to read this previous article. We will report more in detail about hotels 5, 6 and 7 at the end of the breeding season.

To conclude !

To begin with the challenges: the demolition of the Mack Øst building, the removal of the two kittiwake hotels at Strandvegen 8, and the installation of deterrents on the Full Steam building by Pellerin AS have all contributed to the displacement of a significant number of kittiwakes.

It is too early to draw definitive conclusions, but the stress caused by these disruptions may contribute to a lower reproduction rate this year. At the same time, new stations have appeared, mainly in the southern part of the city centre, which may increase tensions with residents, as highlighted by Nordlys on June 22nd.

"Here the nest of the red-listed bird is removed", in Nordlys, 22 June 2025.

On a positive note, our observations show that kittiwake hotels such as Hotel 3 can be successful when well-designed and placed in suitable locations. This supports the idea that alternative nesting structures are a viable part of the solution for coexisting with kittiwakes in Tromsø.

Moreover, the growing number of Kittiwalkers is a strong and encouraging sign of public support for kittiwake protection. Their increasing involvement is truly inspiring, and this report would not have been possible without their valuable contributions. A big thank-you to this dedicated community of kittiwake supporters!

We will report again at the end of the season. In the meantime, feel free to reach out and join the next Kittiwalker workshop!

Kittiwalkers workshop in Tromsø in spring 2025.

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All data presented in this article was collected with the help of volunteers. While we train our volunteers to be as accurate as possible, working with citizen science data presents certain challenges. We have done our best to process the data carefully to provide representative figures for this story.

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