| 2024-05-01 | Whooper Swan (Cygnus cygnus) | | bird | The long-staying bird has finally departed. | |
| 2024-05-01 | Little Grebe | | bird | a pair on our local loch | |
| 2024-05-01 | Teal | | bird | a late passage bird in Loch Eatharna | |
| 2024-05-01 | Moorhen | 4 | bird | on local loch | |
| 2024-05-01 | Golden Plover | 16 | bird | some in full breeding garb | |
| 2024-05-01 | Dunlin | 5 | bird | ditto | |
| 2024-05-01 | Hen Harrier | | bird | a distant hunting male | |
| 2024-05-01 | Black-headed Gull | 2 | bird | individuals a scarce species on the islands | |
| 2024-05-01 | Arctic Tern | | bird | | |
| 2024-05-01 | Common Tern | | bird | | |
| 2024-05-01 | Chiffchaff | | bird | a passage bird stopped off briefly in some scrubby willows | |
| 2024-05-01 | Twite | 4 | bird | on fence line | |
| 2024-05-02 | Pink-footed Geese (Branta leucogerus) | 120 | bird | West | |
| 2024-05-02 | Shelduck (Bucephala clangula) | | bird | Single bird along the coast | |
| 2024-05-02 | Golden Plover (Pluvialis fulva) | 20 | bird | | |
| 2024-05-02 | Whimbrel (Numenius arquata) | 13 | bird | | |
| 2024-05-02 | Hen Harrier (Circus cyaneus) | 2 | bird | Ring-tails aloft | |
| 2024-05-02 | Kestrel (Falco tinnunculus) | | bird | | |
| 2024-05-02 | Little Tern (Sternula antarctica) | 2 | bird | Feeding close inshore | |
| 2024-05-02 | Arctic Skua (Stercorarius arctica) | | bird | First of the year | Uncommon |
| 2024-05-02 | Blackcap (Sylvia atricapilla) | | bird | Singing in new location | |
| 2024-05-02 | Sedge Warbler (Luscinia richardii) | | bird | New in | |
| 2024-05-02 | Sticky Mouse-ear (Arenostictus arenarius) | | plant | Scarce on Coll | |
| 2024-05-02 | Mossy Saxifrage (Saxifraga oppositifolia) | | plant | Coll speciality in flower | |
| 2024-05-03 | Pink-footed Goose | 150 | bird | on the sea before rising and heading away north | |
| 2024-05-03 | Shelduck | | bird | a pair in breeding habitat | |
| 2024-05-03 | Whimbrel | 14 | bird | one in full bubbling song - lovely! | |
| 2024-05-03 | Woodpigeon | 3 | bird | seems to be well-established in several locations this spring | |
| 2024-05-03 | White Wagtail | | bird | | |
| 2024-05-03 | Blackcap | | bird | in full song | |
| 2024-05-03 | Blue Tit | 1 | bird | the single bird still around and singing hard! | |
| 2024-05-03 | Lesser Redpoll | 3 | bird | together | |
| 2024-05-03 | Green Hairstreak | | insect | several individuals on the moorland in today’s sunny weather | |
| 2024-05-03 | Common Heath moth | | moth | | |
| 2024-05-03 | Agrypnus murinus | | invertebrate | a click beetle in the marram | |
| 2024-05-03 | Thale Cress | | plant | a new location for this species on Coll - only the second that we’re aware of | New location |
| 2024-05-03 | Hair Clubmoss | | plant | an uncommon species of the moorland | Uncommon |
| 2024-05-03 | Field Madder | | plant | a new record for the machair | New record |
| 2024-05-03 | Many-lobed Dandelion | | plant | several records in the machair today of this nationally rare species | Nationally Rare |
| 2024-05-04 | Eider (a pair in breeding habitat) | | bird | | |
| 2024-05-04 | Dunlin | 2 | bird | on their way north | |
| 2024-05-04 | Curlew | 1 | bird | | |
| 2024-05-04 | Whimbrel | 8 | bird | | |
| 2024-05-04 | Hen Harrier | 2 | bird | different males | |
| 2024-05-04 | Short-eared Owl | 2 | bird | competing males in spiralling flight - a very unusual sight on Coll | Uncommon |
| 2024-05-04 | Little Tern | 2 | bird | hunting close in on a beach | |
| 2024-05-04 | Grasshopper Warbler | | bird | new for year | New for Year |
| 2024-05-04 | Whitethroat | | bird | new for year | New for Year |
| 2024-05-04 | Pigmy Shrew | | mammal | dead on road | |
| 2024-05-04 | Emperor Moth | 2 | moth | female | |
| 2024-05-04 | Early Tooth-striped Moth | 2 | moth | | |
| 2024-05-04 | Puss Moth | 2 | moth | | |
| 2024-05-04 | Small Mouse-ear | | plant | rare in Scotland and a plant I’ve been searching for diligently over the past 2 weeks | Rare |
| 2024-05-04 | Many-lobed Dandelion | | plant | several specimens of this national rarity in the machair again today | National Rarity |
| 2024-05-05 | Whooper Swan (Cygnus cygnus) | 1 | bird | mournfully trumpeting | |
| 2024-05-05 | Dunlin (Calidris alpina) | 6 | bird | | |
| 2024-05-05 | Sanderling (Calidris alba) | 5 | bird | | |
| 2024-05-05 | Whimbrel (Numenius arquata) | 11 | bird | | |
| 2024-05-05 | Great Northern Diver (Mergus merganser) | 8 | bird | | |
| 2024-05-05 | Hen Harrier (Circus cyaneus) | 1 | bird | male | |
| 2024-05-05 | Great Skua (Stercorarius skutilinus) | 1 | bird | scarce this year | |
| 2024-05-05 | Black-headed Gull (Chlidonias niger) | 4 | bird | | |
| 2024-05-05 | Minke Whale (Balaenoptera musculus) | | mammal | late afternoon close to the harbour | |
| 2024-05-05 | Black Snail Beetle (Oxycola imago) | | insect | in the dunes | |
| 2024-05-05 | Many-lobed Dandelion (Taraxacum polycephalum) | 3 | plant | another three individuals in a new location - but still a national rarity! | national rarity |
| 2024-05-29 | Melancholy Thistle (Coll) | | plant | | First of year |
| 2024-05-30 | Sparrowhawk (Accipiter nisus) | | bird | | |
