City Nature Challenge: Why La Paz


Though I was unable to contribute observations to the City Nature Challenge this year, I have been able to identify quite a few observations as part of several projects, including my project on Lizards of the Amazon Region. Turns out, La Paz, Bolivia, falls within boundaries of the Amazon Region on iNaturalist and I knew La Paz was a powerhouse of observations from following the forum, but didn’t really notice it before now. Specifically, as part of that project I have identified (or tried to) all 20,000 lizards of the Amazon Region and so now just work to keep current on identifications as a means of gaining insight into seasonal changes in observations. Usually, the project receives 110-130 observations per week, so imagine my surprise when I checked on Sunday morning to find 3X the weekly observations alone yet to be identified and that pace of several week’s worth of observations in a day has continued since then.

Below is a table of projects ranked in the top eight of each of the two regions using data only from those listed on the umbrella projects splash pages for those regions (data were tabulated as of Tuesday, April 30 and so have changed since then, but the ranks haven’t changed much). Listed are number of observations in each project and the number of members of each project.

It’s Bolivia, not just La Paz

What the data reveal is that it’s not La Paz alone, but Cochabamba and Trinidad (also part of the Amazon Region) that are dominating not only the North/South America project, but also the Eurasia/Africa/Oceania project…so globally.

The easiest explanation is that the number of project members is high in those Bolivian projects. With the exception of Tagum City, those three Bolivian project have the three top membership numbers. Clearly buy-in by the people of those projects is incredibly high. But as I identified I kept asking myself: Why La Paz? Why Bolivia? So, I reached out to a number of iNaturalist identifiers and observers who are either from Bolivia or who work in Bolivia with whom I had interacted prior to this over the last year and felt I could trust their insight. I asked them straight up: Why La Paz? Why Bolivia? I summarize below what I learned so that we might learn from Bolivia’s apparent success.

How it started

La Paz burst onto the City Nature Challenge scene in 2019 but narrowly lost out to Cape Town (by <7000 observations) in terms of number of observations. This was the first year La Paz participated. Apparently, in developing the project for La Paz, the Wildlife Conservation Society (WCS) sent staff to schools in La Paz and El Alto in order to invite and trains students and teachers to participate. This included an active social media presence with invitations to participate. YouTubers picked up on this and provided videos for training in how to make records. In addition, the WCS invited experts from various taxonomic groups to participate in identification session which included meeting in a local restaurant with coffee and refreshments. The WCS continues to support the training of observers, so this effect is probably ongoing. In short, the WCS made (and continues to make) a multi-pronged outreach program on various social media outlets to organize both ends of the process: observations and identifications.

Government support

This led to the government of Bolivia (by context, I took this to mean the government of La Paz, not of Bolivia) getting wind of the Challenge who apparently sought to improve their international reputation from merely a poor cocaine-producing nation to one rich in biodiversity and proud of their biotic heritage (let me be clear, this reputation was how one Bolivian explained it to me…I never thought of Bolivia in this way). How did they do this? Simple, them required government officials to make at least 30 records per person. Now, I don’t know how many people actually did this, but if it was 1000 government employees we’re talking 30,000 observations at bare minimum. It’s not clear if the government still requires this of their employees, but apparently at some point Trinidad did this as well. Regardless, the effect, when combined with the student training by the WCS, was to turbo-charge the efforts of La Paz. After a sharp downturn in 2020 (~3000 observations) and 2021 (<1000), rebounded in 2022 with over 134,000 observations….enough to lead the Challenge by over 68,000 observations MORE than the 66,000 of Cape Town. La Paz has never looked back leading the way in each of the two years since then.

Civic pride

In addition to national pride mentioned above, something apparent is the civic pride exhibited by each of the cities represented in Bolivia. Cochabamba actually beat out La Paz in 2021, which apparently didn’t sit well with La Paz. However, it is interesting to note that Cochabamba (‘mistakenly’ in the words of one Bolivian) added the entire Province as their area for observations, not just the metropolitan area as in La Paz. However, it was pretty clear in my conversations with the people I contacted that civic pride was a major driving force in the rebound La Paz experienced as well as the emergence in 2024 of Cochabamba and Trinidad as global players in the Challenge.

Inherent biodiversity

One person I talked to thought a major factor, for La Paz at least, is the geography of the city. While Trinidad (160 meters above sea level) and Cochabamba (2558 m) are lower than La Paz (mean elevation 3640 m), the range of elevations within the metropolitan area of La Paz is from 500-4000 m and encompasses several distinct ecoregions in that elevational range. So, this may account for the greater number of species observed than in other cities, though one person pointed out that many of the required observations from government officials were of plants and birds from near their homes or nearby parks, as well as pets.

Broadening participation

One thing mentioned is that the ongoing efforts by the WCS includes training in different parts of the city, not just the same places, so as to recruit more and more individuals. In addition, apparently the National Museum of Natural History in La Paz specifically engaged its staff by deploying camera traps and bat detectors for additional types of observations. Similarly, other environmental groups are actively engaging the populations in each of the Bolivian cities participating to recruit and train observers, none of which is specifically organized by any one entity. In short, broad support by the local population and national/international environmental organizations as well as very active project organizers.

Further reading

Bolivians are aware of their status as Challenge powerhouse and quite proud of their contributions to iNaturalist. They have even worked to explain/justify this in the scientific record by publishing a paper in fall of 2023 exploring their experiences (Flores-Turdera et al. 2023). I include a ResearchGate link to the original paper as well as an English translation (via of the abstract for you to consider.
Citizen science encourages people’s participation in scientific research projects. One of the best-known initiatives is the City Nature Challenge contest, aimed at recording biodiversity in cities through the iNaturalist application. The metropolitan region of La Paz, Bolivia, participated in this contest in 2019 and 2022 under the name Reto Ciudad Naturaleza, thanks to the support of the Wildlife Conservation Society (WCS) Bolivia, the Biology Department and the Institute of Ecology of the Universidad Mayor de San Andrés (UMSA) and the National Museum of Natural History (MNHN), which formed an organizing committee. The objective was to strengthen the links of the urban population with nature, in order to generate data on knowledge and conservation of biodiversity. The activities consisted of the promotion and dissemination of the contest, training events in the use of iNaturalist, photographic records, taxonomic identification and delivery of certificates to the participants. In 2019, La Paz competed with 158 cities and achieved eighth place in number of species (3,005), third place in number of participants (1,500) and second in number of observations (46,931). In 2022, 447 cities participated, and La Paz led in the three categories of the contest, with 137,345 observations, 5,320 species and 4,296 participants. Beyond these results, the commitment of the citizens of La Paz to its biodiversity stands out, which has an impact on an increasingly closer link between the urban population and its natural environment.

Finally, thank you to those whom I contacted willing to share their thoughts on why La Paz and why Bolivia.

Comments? Thoughts? Ideas? What here can be replicated in your city next Challenge?


Live data for all CNC participants, on one table:

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This year adds Graz in Austria.

I remember the altitude and biodiversity explanation for La Paz.
And biodiversity for Hong Kong too.

Honestly, given the experiences of the people who have helped to clean up the flood of cultivated plants (nearly 50% in 2023) and unknowns entered as part of the CNC in La Paz, I wouldn’t exactly consider it an example to be imitated. A lesson on some of the things not to do, maybe…

The participation numbers are impressive, absolutely. But the people going out and motivating citizens to take photographs of nature seem to have neglected to develop any concept for providing guidance on what iNat is and how to use it. They also seem to have neglected to develop a strategy for recruiting local IDers to look at those tens of thousands of observations. Documenting the local biodiversity doesn’t mean anything if there’s nobody to sort and classify what has been found.

It would be interesting to see how many users who participate in the CNC in La Paz continue to be active on iNat even after the CNC has ended. I would consider this a much better measure of success than the sheer number of observations.

Graz (and Austria in general) has a very active, established iNat community, so they are able to draw on a solid base of experienced users, many of whom have some background in biology. The observation:observer ratio is fairly high – i.e., there are relatively fewer observers posting lots of observations rather than many casual users posting a few observations. The taxonomic distribution of the observations is also notable, with nearly half being arthropods. It is a fairly biodiverse region, and the area included in the CNC extends quite a bit outside Graz proper and includes at least one nature reserve – it is not all “urban” nature in a narrow sense.


As someone who has IDed a lot of stuff in La Paz over the last 3 CNCs, I regularly come across accounts that are active only for the days of the CNC, then do not touch iNat again until the next CNC. There are obviously some dedicated iNat users in La Paz, but there are hundreds/thousands of users who only do the CNC.

Because of the emphasis on quantity not quality, some users do things like uploading the same photo over and over again as new observations each time. Or if they take 5 photos of the same organism, they will upload those as 5 observations. Others share photos, so that multiple people upload the exact same set of photos. This year I have found a few cases of people uploading photos again that they used in 2023 or 2022, just changing the date.

Because La Paz CNC allow casual observations, I feel intimately acquainted with every street tree, garden bed, and house plant in the whole city!

So yeah, a few examples I would prefer other cities did not emulate.


Another example I would prefer people not to emulate for must have MORE obs.
Perfect picture of a pair of ducks - taken to RG. Tick.
But then uploaded as a fresh obs … bit of grass on the left … clump of reeds on the right … branch across the top … shrubby something over there! No, thank you.

I would like to see a focus on recruiting numbers for active iNatters. Who tested the waters last CNC, and is still (not just again for CNC, and done) with us??

@spiphany I found this on their project

Graz und seine Umgebung zählen zu den artenreichsten Gebieten Mitteleuropas

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