Sync and cloud storage

What is bird?

Q: How do I see what iCloud Drive syncs?

Run brctl status in Terminal. It lists the iCloud containers and their sync state.

Q: Is bird the same as cloudd?

No. bird syncs iCloud Drive files. cloudd syncs the data of apps that use CloudKit.

bird is one of the macOS daemons behind iCloud Drive. When files in iCloud Drive, or in Desktop and Documents with that option on, change, bird uploads and downloads them.

Process: birdMade by AppleApplies to: macOS 14 Sonoma and later. Checked on macOS 27.2.Checked: 1 November 2026

Short answer

Part of macOS. It runs iCloud Drive, so its traffic is your iCloud Drive files going up and down.

Block with care

Blocking it stops iCloud Drive sync on this Mac. Your files stay here, but changes stop reaching your other devices.

Path: /System/Library/PrivateFrameworks/iCloudDriveCore.framework/Versions/A/Support/bird
launchd label: com.apple.bird
Signing identifier: com.apple.bird

What it is

The man page calls bird one of the daemons “backing the Documents in the Cloud feature”. That feature is iCloud Drive.

The program is in the iCloudDriveCore framework of macOS. launchd starts it for each user as com.apple.bird.

The man page points to brctl, a command that manages the CloudDocs daemon. brctl status lists the iCloud containers and their sync state.

Why it uses the network

Uploads. Files that you add to iCloud Drive, or change there, go to iCloud.
Downloads. Files that you add or change on your other devices come to this Mac.
Desktop and Documents. With Desktop & Documents Folders on, Apple stores those two folders in iCloud Drive too. Everything you save there syncs.

How much is normal

Traffic after you add or change files is usual. The amount is the size of the files, plus a little overhead.

Large folders take a long time on a slow upload. The sync then continues for hours, which is expected.

Look closer if a sync never ends. A file that can't sync can stay in the queue. brctl status shows what is waiting.

When it uses a lot, and why

You turn on Desktop & Documents Folders. Apple moves both folders into iCloud Drive. Everything already in them uploads, which can be gigabytes.
A new Mac. After you sign in and turn on iCloud Drive, the files that this Mac keeps locally download from iCloud.
Big files in a synced folder. Video exports, disk images and archives saved to the Desktop or Documents upload in full. A build or download folder inside them uploads too.

Is it safe to block?

Block with care

Blocking it stops iCloud Drive sync on this Mac. Your files stay here, but changes stop reaching your other devices.

What breaks if you block it

Files you add or change in iCloud Drive don't upload, and changes from your other devices don't arrive.
Files kept only in iCloud can't download to this Mac until you allow it again.
With Desktop & Documents Folders on, those folders stop syncing too.

Blocking means a firewall rule that refuses its connections. Don’t quit or disable a macOS process to save data: macOS starts it again, and other features depend on it.

Reduce its use

Do large copies into iCloud Drive on your usual network, not on a hotspot.
Keep build folders, disk images and big downloads out of Desktop and Documents, or out of iCloud Drive.
Choose Apple menu › System Settings. Click your name, then click iCloud. Click Drive.
To stop the sync of the Desktop and Documents folders, turn off Desktop & Documents Folders. Read Apple's article first. It explains what stays where.
On a hotspot or a capped plan, turn on Low Data Mode. Choose Apple menu › System Settings › Wi-Fi. Click Details next to the network, then turn on Low Data Mode.
Don't quit bird in Activity Monitor. macOS starts it again, and the Finder depends on it.

See how much it uses

Open Activity Monitor from Applications › Utilities. Click Network, then search for bird.
In Terminal, watch only this process. Press d to show the change per second, and q to quit.
```
nettop -p bird -P
```
See what iCloud Drive is still syncing.
```
brctl status
```

With Kilobat

In the Kilobat app list, search for bird. Its row shows the live rate and what it moved today.
In Connections, click the ⓘ button on one of its rows. The popover shows this page’s short answer, without going online.
In Terminal, ask the same question. Add --json for scripts and agents.
```
kilobat explain 'bird'
```
Show its traffic over one day.
```
kilobat bandwidth 'bird' day
```
Through MCP, an AI agent asks explain_connection with the process name. It gets the same facts.

The live view and the explanations are free. History in the app needs Kilobat Pro. Blocking needs Pro and the network filter: see the network filter, Protection and the hotspot data saver.

Hosts it contacts

Apple and the maker document these hosts for this feature. A process can also contact others; Kilobat’s Connections tab shows what it actually opens on your Mac.

*.icloud-content.comAn Apple domain for iCloud services. Large uploads and downloads of iCloud content, such as files and photos, can go to hosts under it.Apple →*.icloud.comApple's iCloud domain. Apple lists *.icloud.com for iCloud services; specific hosts under it have their own pages.Apple →

Questions

Is bird a virus?

No. It is part of macOS, in the iCloudDriveCore framework, signed by Apple, and it has a man page.

How do I see what iCloud Drive syncs?

Run brctl status in Terminal. It lists the iCloud containers and their sync state.

Is bird the same as cloudd?

No. bird syncs iCloud Drive files. cloudd syncs the data of apps that use CloudKit.

Sources

bird(8) and brctl(1), man pages installed with macOS 27.2
launchd property list com.apple.bird, macOS 27.2
Apple Support: Change iCloud settings on Mac
Apple Support: Add your Desktop and Documents files to iCloud Drive
Apple Support: Use Apple products on enterprise networks

Checked on 1 November 2026.