Jaapiella veronicae
- Group
- True flies
- Peak month
- August
- Records since 2000
- 742
Jack Snipe
- Group
- Birds
- Peak month
- October
- Records since 2000
- 12,579
Jackrogersella cohaerens
- Group
- Fungi
- Peak month
- October
- Records since 2000
- 140
Jackrogersella minutella
- Group
- Fungi
- Peak month
- April
- Records since 2000
- 114
Jacob's-ladder
- Group
- Flowering plants
- Peak month
- June
- Records since 2000
- 420
Jaera albifrons
- Group
- Crustaceans
- Peak month
- September
- Records since 2000
- 241
Jaera ischiosetosa
- Group
- Crustaceans
- Peak month
- January
- Records since 2000
- 59
Jaera nordmanni
- Group
- Crustaceans
- Peak month
- April
- Records since 2000
- 66
Jagged Germanderwort
- Group
- Liverworts
- Peak month
- July
- Records since 2000
- 3,112
Jagged Notchwort
- Group
- Liverworts
- Peak month
- July
- Records since 2000
- 1,104
Jamesiella anastomosans
- Group
- Lichens
- Peak month
- October
- Records since 2000
- 415
Jania rubens
- Group
- Seaweeds and algae
- Peak month
- May
- Records since 2000
- 304
Janira maculosa
- Group
- Crustaceans
- Peak month
- August
- Records since 2000
- 1,303
Janua heterostropha
- Group
- Worms (annelids)
- Peak month
- August
- Records since 2000
- 98
Japanese barberry
- Group
- Flowering plants
- Peak month
- April
- Records since 2000
- 206
Japanese flowering cherry
- Group
- Flowering plants
- Peak month
- April
- Records since 2000
- 50
Japanese Honeysuckle
- Group
- Flowering plants
- Peak month
- June
- Records since 2000
- 684
Japanese Knotweed
- Group
- Flowering plants
- Peak month
- June
- Records since 2000
- 30,167
Japanese Larch
- Group
- Conifers
- Peak month
- April
- Records since 2000
- 223
Japanese Leafhopper
- Group
- True bugs
- Peak month
- August
- Records since 2000
- 167
Japanese Quince
- Group
- Flowering plants
- Peak month
- September
- Records since 2000
- 611
Japanese Rose
- Group
- Flowering plants
- Peak month
- August
- Records since 2000
- 9,179
Japanese skimmia
- Group
- Flowering plants
- Peak month
- March
- Records since 2000
- 106
Japanese spindletree
- Group
- Flowering plants
- Peak month
- July
- Records since 2000
- 2,071
Japanese Sweet Coltsfoot
- Group
- Flowering plants
- Peak month
- March
- Records since 2000
- 567
Japanese wineberry
- Group
- Flowering plants
- Peak month
- July
- Records since 2000
- 266
Japewia lichen
- Group
- Lichens
- Peak month
- July
- Records since 2000
- 52
Japewiella tavaresiana
- Group
- Lichens
- Peak month
- May
- Records since 2000
- 196
Jasmine tobacco
- Group
- Flowering plants
- Peak month
- August
- Records since 2000
- 163
Jasmineira caudata
- Group
- Worms (annelids)
- Peak month
- July
- Records since 2000
- 2,022
Jasmineira elegans
- Group
- Worms (annelids)
- Peak month
- July
- Records since 2000
- 1,997
Jassa marmorata
- Group
- Crustaceans
- Peak month
- August
- Records since 2000
- 70
Jassargus distinguendus
- Group
- True bugs
- Peak month
- July
- Records since 2000
- 132
Javesella discolor
- Group
- True bugs
- Peak month
- June
- Records since 2000
- 93
Javesella dubia
- Group
- True bugs
- Peak month
- May
- Records since 2000
- 400
Javesella forcipata
- Group
- True bugs
- Peak month
- June
- Records since 2000
- 50
Javesella pellucida
- Group
- True bugs
- Peak month
- July
- Records since 2000
- 1,069
Jaxea nocturna
- Group
- Crustaceans
- Peak month
- August
- Records since 2000
- 343
Jeffrey's Goby
- Group
- Fish
- Peak month
- March
- Records since 2000
- 238
Jelly Ear
- Group
- Fungi
- Peak month
- October
- Records since 2000
- 7,281
Jelly Lichen
- Group
- Lichens
- Peak month
- November
- Records since 2000
- 1,155
Jelly lichen
- Group
- Lichens
- Peak month
- May
- Records since 2000
- 355
Jelly lichen
- Group
- Lichens
- Peak month
- May
- Records since 2000
- 237
Jelly Rot
- Group
- Fungi
- Peak month
- October
- Records since 2000
- 748
Jellybaby
- Group
- Fungi
- Peak month
- October
- Records since 2000
- 1,016
Jenner's cynodontium moss
- Group
- Mosses
- Peak month
- July
- Records since 2000
- 124
Jersey Tiger
- Group
- Butterflies and moths
- Peak month
- August
- Records since 2000
- 3,666
Jerusalem artichoke
- Group
- Flowering plants
- Peak month
- September
- Records since 2000
- 171
Jet Ant
- Group
- Bees, wasps and ants
- Peak month
- July
- Records since 2000
- 751
Jewel Anemone
- Group
- Jellyfish, corals and anemones
- Peak month
- May
- Records since 2000
- 5,851
Jewel reed beetle
- Group
- Beetles
- Peak month
- June
- Records since 2000
- 717
Jewelweed Leafminer
- Group
- True flies
- Peak month
- August
- Records since 2000
- 223
Joergensen's Notchwort
- Group
- Liverworts
- Peak month
- May
- Records since 2000
- 51
John Dory
- Group
- Fish
- Peak month
- November
- Records since 2000
- 8,832
Jointed Rush
- Group
- Flowering plants
- Peak month
- July
- Records since 2000
- 6,027
Jordaniella nivosa
- Group
- Molluscs
- Peak month
- April
- Records since 2000
- 88
Jorunna tomentosa
- Group
- Molluscs
- Peak month
- August
- Records since 2000
- 371
Juicy Silk-moss
- Group
- Mosses
- Peak month
- April
- Records since 2000
- 5,833
Julus scandinavius
- Group
- Millipedes
- Peak month
- June
- Records since 2000
- 124
July belle
- Group
- Butterflies and moths
- Peak month
- July
- Records since 2000
- 139
July Highflyer
- Group
- Butterflies and moths
- Peak month
- July
- Records since 2000
- 4,513
Jumping plant louse
- Group
- True bugs
- Peak month
- June
- Records since 2000
- 907
Junco hyemalis
- Group
- Birds
- Peak month
- April
- Records since 2000
- 189
Juncorrhiza aschersoniana
- Group
- Fungi
- Peak month
- August
- Records since 2000
- 65
Juncorrhiza casparyana
- Group
- Fungi
- Peak month
- November
- Records since 2000
- 72
Juneberry
- Group
- Flowering plants
- Peak month
- April
- Records since 2000
- 191
Jungermann's platydictya moss
- Group
- Mosses
- Peak month
- April
- Records since 2000
- 83
Jungermannia borealis
- Group
- Liverworts
- Peak month
- July
- Records since 2000
- 71
Junghuhnia nitida
- Group
- Fungi
- Peak month
- April
- Records since 2000
- 133
Juniper carpet
- Group
- Butterflies and moths
- Peak month
- October
- Records since 2000
- 250
Juniper Haircap
- Group
- Mosses
- Peak month
- March
- Records since 2000
- 9,683
Juniper Prongwort
- Group
- Liverworts
- Peak month
- June
- Records since 2000
- 743
Juniper pug
- Group
- Butterflies and moths
- Peak month
- July
- Records since 2000
- 218
Juniper Shieldbug
- Group
- True bugs
- Peak month
- September
- Records since 2000
- 2,649
Juxtacribrilina annulata
- Group
- Bryozoans
- Peak month
- April
- Records since 2000
- 59