BRPC Badge levels
Ben Holt
2026-10-05
Badge levels
This analysis will help set the bronze, silver and gold thresholds for each badge in the BioBlitz Battle app, using the full Big Rock Pool Challenge dataset from iNaturalist.
The aim is to make bronze achievable for newcomers, silver a meaningful milestone and gold a substantial achievement. We will look at the spread of results for each badge to propose levels that recognise progress and encourage continued participation.
Thresholds for wildlife recording badges will be based on records verified to Research Grade level, thresholds for attendance based badges will be based on all records.
Rock Pooler Badge
Rewards participants for their overall contribution to the Big Rock Pool Challenge, measured using total rarity points across all records. Bronze, Silver and Gold thresholds will be based on the distribution of total rarity points earned from verified records by each participant.
- Only records that have reached Research Grade are included.
- Each record contributes the rarity score assigned to its taxon under the BRPC rarity scoring system.
- Rarity points are summed across all of the participant’s BRPC records.
- Participants are identified using their iNaturalist user ID, rather than username, so changing an iNaturalist username does not affect their progress.
Recommended thresholds
The distribution of total rarity points is strongly right-skewed, with most participants accumulating between approximately 10 and 1,000 points and a much smaller number reaching several thousand points. For the Rock Pooler badge, the following thresholds are proposed:
- Bronze: 100 rarity points
- Silver: 1,000 rarity points
- Gold: 10,000 rarity points
Naturalist Badge
Rewards participants for the diversity of taxa they record. Thresholds will be based on the number of different verified species recorded by each participant across the project.
- Only records that have reached Research Grade are included.
- All of the participant’s BRPC records are considered together.
- The taxon list is leaf pruned: where both an ancestor and one of its descendants have been recorded, the ancestor is removed from the count. For example, if a participant has records identified as both Carcinus and Carcinus maenas, these do not count as two separate taxa; only the more specific leaf taxon is counted.
- The resulting number of unique leaf taxa is used for badge progress.
- Participants are identified using their iNaturalist user ID, so username changes do not split their recording history.
The distribution of leaf-pruned taxon richness is strongly right-skewed. Most participants have recorded relatively small numbers of taxa, while a smaller group of highly active participants have recorded more than 100. The highest current individual total is just over 200 taxa.
For the Naturalist badge, the following thresholds are proposed:
- Bronze: 25 taxa
- Silver: 100 taxa
- Gold: 250 taxa
Regular Badge
Rewards participants for taking part repeatedly rather than attending a single BioBlitz. Thresholds will be based on the number of different BRPC events in which each participant has contributed records.
An event is defined as a unique combination of BRPC hub and observation date. Hub membership is determined by matching the iNaturalist place IDs associated with each observation against the BRPC hub place-ID lookup.
All observations are eligible for this badge regardless of verification status. Records made outside the defined hub locations are not used to identify event attendance. Multiple records made by the same participant at the same hub on the same date count as one event.
Participants are identified using their stable iNaturalist user ID, so changes to username do not affect their accumulated attendance.
Recommended thresholds
The distribution of event attendance is highly skewed, with the large majority of participants currently represented at only one hub event. Repeat attendance therefore represents an important behaviour to recognise and encourage.
For the Regular badge, the following thresholds are proposed:
- Bronze: 2 events
- Silver: 5 events
- Gold: 10 events
Bronze is deliberately awarded on the second event, recognising the important step from first-time participant to returning participant. Silver represents repeated engagement with the programme, while Gold recognises sustained participation across multiple events.
Wanderer Badge
Rewards participants for exploring and contributing to different BRPC hubs. Thresholds will be based on the number of different hubs at which each participant has contributed records.
The Wanderer badge is based on the number of different BRPC hubs at which a participant has contributed records.
Hub membership is determined by matching the iNaturalist place IDs associated with each observation against the BRPC hub place-ID lookup. All observations are eligible regardless of verification status.
Each currently recognised hub is counted separately, including Mount Batten and Firestone Bay in Plymouth.
Participants are identified using their stable iNaturalist user ID, so changes to username do not affect their accumulated progress.
Recommended thresholds
The large majority of participants have contributed records at a single BRPC hub. Recording at multiple hubs is currently relatively unusual and therefore provides a useful opportunity to recognise participants who explore the wider BRPC network.
For the Wanderer badge, the following thresholds are proposed:
- Bronze: 2 hubs
- Silver: 3 hubs
- Gold: 5 hubs
Crab Hunter Badge
Rewards participants for finding a range of crab species. Thresholds will be based on the number of qualifying crab species recorded by each participant, rather than the total number of crab records.
The Crab Hunter badge is based on the number of different crab species recorded by a participant.
- Only records that have reached Research Grade are included.
- Qualifying crabs include species within Brachyura (true crabs; iNaturalist taxon ID 121639) and Anomura (iNaturalist taxon ID 123825).
- Only records identified to species level are included.
- Each crab species is counted only once per participant, regardless of how many times it has been recorded.
- Participants are identified using their stable iNaturalist user ID, so changes to username do not affect progress.
| Taxon ID | Scientific name | Common name |
|---|---|---|
| 496884 | Atelecyclus rotundatus | Circular Crab |
| 120553 | Cancer pagurus | Edible Crab |
| 52523 | Carcinus maenas | European Green Crab |
| 210291 | Clibanarius erythropus | Saint Piran’s Hermit Crab |
| 549751 | Corystes cassivelaunus | Masked crab |
| 326066 | Diogenes pugilator | South-claw Hermit Crab |
| 342260 | Galathea squamifera | Black Squat Lobster |
| 338037 | Galathea strigosa | Spiny Squat lobster |
| 48904 | Hemigrapsus sanguineus | Asian Shore Crab |
| 491876 | Hemigrapsus takanoi | Brush-clawed Shore Crab |
| 326067 | Inachus phalangium | Leach’s spider crab |
| 363943 | Macropodia rostrata | Long-legged Spider Crab |
| 447552 | Maja brachydactyla | Spiny Spider Crab |
| 210219 | Necora puber | Velvet Swimming Crab |
| 152975 | Pagurus bernhardus | Common Hermit Crab |
| 574162 | Pagurus cuanensis | Atlantic Hairy Hermit Crab |
| 320290 | Pilumnus hirtellus | Hairy Crab |
| 777268 | Pirimela denticulata | Toothed Crab |
| 831262 | Pisa tetraodon | NA |
| 622518 | Pisidia longicornis | Long-clawed Porcelain Crab |
| 1562918 | Polybius corrugatus | Wrinkled Swimming Crab |
| 1551489 | Polybius depurator | Harbour Crab |
| 1562919 | Polybius navigator | Arch-fronted Swimming Crab |
| 1551491 | Polybius pusillus | Dwarf Swimming Crab |
| 130089 | Porcellana platycheles | Hairy Porcelain Crab |
| 603932 | Xantho hydrophilus | Montagu’s Crab |
| 701003 | Xantho pilipes | Risso’s Crab |
Recommended thresholds
The distribution of crab species recorded per participant is strongly skewed towards relatively small numbers. Most participants have recorded only a few crab species, with the highest current individual total being 11 species. Across the BRPC dataset as a whole, 27 qualifying crab species have been recorded.
For the Crab Hunter badge, the proposed thresholds are:
- Bronze – 5 species
- Silver – 10 species
- Gold – 20 species
Rare Find Badge
Rewards participants for finding less commonly recorded taxa. Thresholds will be based on the number of qualifying uncommon or rare taxa recorded by each participant, using the BRPC rarity scoring system.
The Rare Find badge is based on the number of different rare taxa recorded by a participant.
- Only records that have reached Research Grade are included.
- A rare taxon is defined as one with a BRPC rarity score of 50 points or more.
- Each qualifying taxon is counted only once per participant, regardless of how many times it has been recorded.
- Taxa not included in the rarity score list receive the default score of 200 points.
- Subspecies and varieties not included in the rarity list inherit the rarity score of their parent species.
- Participants are identified using their stable iNaturalist user ID, so changes to username do not affect progress.
Recommended thresholds
The distribution of rare taxa recorded per participant is strongly skewed. Most participants who have recorded a qualifying rare taxon have found only one or two, while only a small number have accumulated substantially larger lists.
For the Rare Find badge, the proposed thresholds are:
- Bronze – 1 rare taxon
- Silver – 5 rare taxa
- Gold – 10 rare taxa
A rare taxon is defined as a taxon with a BRPC rarity score of 50 points or more.