Most bookmarks are saved once and never opened again. X, Bluesky, Mastodon, and Nostr clients all list bookmarks newest first, so anything older than a few weeks is out of sight. Birdfeeder brings a few of those older bookmarks back, in two places you already look.
In your weekly summary
Below the posts you bookmarked this week, the summary email shows up to three from your archive. Each one says why it came back: a post whose photo you marked as a favorite, one you saved on this day in an earlier year, or one you wrote a note on. A bookmark that was in the email once stays out for six months, so the picks keep changing from week to week.
On your dashboard
Your dashboard shows one older bookmark above the ones you saved recently. It changes once a day, and "Show another" brings up the next one. Everything you can do with a bookmark works there too: add a note, make it public, or open its photos full size.
Only when there is something to show
Picks come from your own bookmarks only, and start once you have at least 20 bookmarks older than a month. If you want the summary to cover just the current week, turn archive picks off in Settings or from the link at the bottom of any summary.