Birb Nest Not Leveling? Evolution VI and Tier IV

Why a completed Tier III nest can still be blocked

If your Birb is at Evolution V and the nest will not move beyond Tier III, the next thing to check is your bird's evolution. A completed set of nest upgrades does not replace the next evolution requirement. The September 26 update makes the requirement explicit: Nest Tier IV needs Evolution VI.

This also matches the developer's answer to a Steam player who had finished the Level 3 nest while at Evolution 5. In that discussion, the developer explained that the nest follows the bird's evolution and that this particular next step requires Evolution 6. That makes the evolution check more useful than repeatedly looking for an unbought nest upgrade.

Keep the scope of that answer in mind. It identifies the Tier III-to-IV progression gate; it does not say that every upgrade in the nest uses the same requirement or that all future nest tiers will follow a numerical pattern. Use the named requirement for this transition rather than extrapolating a rule for content that has not been announced.

Follow the Archivist story toward Evolution VI

The update adds a new story sequence after defeating the Archivist and places Evolution VI in that new progression. The useful route is therefore: Archivist → new story → Evolution VI → Nest Tier IV. Think of this as a dependency chain, not a promise that beating the boss immediately upgrades the nest.

Start by establishing where your current save sits on that chain. If the Archivist has not been defeated, that is the announced story trigger still ahead of you. If you have defeated the boss and the new sequence is available, continue that progression toward Evolution VI. If you already reached Evolution VI, return to the nest's next-tier requirement rather than repeating earlier progression just because an older guide uses different terminology.

The developer's announcement names the trigger and the resulting evolution, but does not provide a complete room-by-room route or every interaction in the intervening story. This guide therefore does not supply invented dialogue choices, map coordinates or a guaranteed boss build. Follow the game's current story prompts for those intermediate actions.

Before a major transition, keeping a save backup is sensible. The web-to-Steam save guide explains how to preserve the save you intend to use and how to stop safely if a progress conflict appears. A backup is especially useful if you are returning after a long break and also changing platforms.

The older-save Archivist requirement

The most important exception is for a save that had already defeated the Archivist before the new story arrived. The September 26 notes explicitly say older saves must defeat the Archivist again to trigger the new sequence. A historical victory and the new story trigger are not necessarily the same recorded event.

This gives a returning player a concrete action to investigate. If you remember beating the Archivist but cannot find the new progression, check whether that victory predates the update. The announced fix is another victory to trigger the added story, rather than restarting the entire game or buying unrelated nest upgrades.

There is a limit to what this explains. It is a requirement for triggering the new story on an older save, not a universal cure for every missing quest or every save-sync problem. If you are also comparing a browser save with a Steam save, first establish which one is actually loaded. Progress remembered from a different copy cannot tell you what the active copy has completed.

Avoid combining all possible fixes at once. First verify the active save, then its evolution, then whether the new story has been triggered. Changing platforms, importing another file and repeating the boss in one session would make it harder to identify which action changed the result.

Keep Evolution, nest tiers and Parrot Rebirbs separate

Three progression names can appear in the same part of the game, but their unlocks differ. Birb Evolution VI is the bird progression named by the Nest Tier IV requirement. Nest Tier IV is the next nest tier and its associated unlock. Parrot Rebirb III is companion progression that also involves the Archivist.

The shared boss does not make those tracks interchangeable. Completing the third Parrot Rebirb is not the requirement the developer lists for Tier IV. Equally, reaching Evolution VI is not described as an automatic completion of Parrot Rebirb III. When a screen names a prerequisite, check that exact track.

If your real goal is Night Mode, use the Parrot Rebirb III guide for that condition. If your problem is the nest refusing its next tier, keep Evolution VI as the prerequisite you are checking. This avoids spending time on the wrong milestone just because both routes mention the same boss.

What Nest Tier IV unlocks

The September 26 update specifically connects Tier IV with Golden Popcorn upgrade automation. This is a useful reason to finish the progression, but it is also a narrowly named feature. It should not be read as automatic completion of every activity in the nest, the mine or the workshop.

The same update introduces Wood collection, Carpentry projects, permanent decorations, Plank production and repeatable nest expansion upgrades. Those systems appear together in the patch notes, but their presence in one announcement does not make them a single unlock condition. In particular, automatic Sawmill cutting has its own announced requirement: Sawmill level 10 while inside the workshop.

If you are trying to automate Wood-related work, see the Sawmill and Planks guide rather than assuming that Nest Tier IV completes that task. If you are aiming for Golden Popcorn upgrade automation, the Tier IV route is the one the developer explicitly names.

When the prerequisite is satisfied but the nest is still stuck

Once the active save really is at Evolution VI, the evolution gate described here has been met. At that point, check the next-tier information shown in the current game instead of guessing that Evolution VII is needed. The published requirement is VI; there is no basis here for replacing it with a higher number.

If the current screen contradicts the announced requirement, preserve what you can show: the displayed Birb evolution, the nest tier, any requirement text, the platform and whether the save was recently imported or linked. These details distinguish a progression problem from loading a different save. A redacted screenshot can communicate the contradiction without giving anyone account access.

Do not erase or overwrite your save as a troubleshooting shortcut. If a conflict dialog appears, the October 2 update provides an X that closes it without selecting either save. Resolve that comparison before treating missing nest progress as a new progression requirement.

This guide covers the September 26 Tier IV and Evolution VI rules, with the developer's October Steam discussion as a second confirmation of the nest gate. If a later update changes the requirement, the current game's wording and the newer developer announcement take precedence.