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URCHIN RESEARCHIN’: SEA HEDGEHOGS OF THE REEF


Long-spined sea urchin Diadema antillarum (Melinda Rodgers / Dive Abaco)

 

URCHIN RESEARCHIN’: SEA HEDGEHOGS OF THE REEF

The long-spined sea urchin Diadema antillarum featured in this post is one of those creatures that handily offers its USP in its name, so you know what you are dealing with. Something prickly, for a start. These are creatures of the reef, and many places in the Caribbean and in the western Atlantic generally sustain healthy populations.

Long-spined sea urchin Diadema antillarum (Melinda Rodgers / Dive Abaco)

These animals are essentially herbivores, and their value to vulnerable coral reefs cannot be overstated. Where there is a healthy population of these urchins, the reef will be kept clean from smothering algae by their methodical grazing. They also eat sea grass.

Long-spined sea urchin Diadema antillarum (Melinda Rodgers / Dive Abaco)

HOW DO THE SPINES OF DIFFERENT KINDS OF URCHIN COMPARE?

Small sea urchin species have spines a few cms long at most. The long-spine variety can exceed 10 cms, and the largest may have spines up to 30 cms (= 1 foot) long. The length, as shown here, means that when the creatures are safely lodged in crevices near their algae supply, their spines remain very visible.
 
Long-spined sea urchin Diadema antillarum (Melinda Riger / G B Scuba)
 
Anatomy of a long-spined sea urchin. You may possess a few of these organs yourself…

Long-spined sea urchin Diadema antillarum anatomy diagram (wiki)

Long-spined sea urchin Diadema antillarum (Melinda Rodgers / Dive Abaco)

CAN YOU GIVE US A TEST, PLEASE?

As with SAND DOLLARS and similar creatures, the skeleton of a sea urchin is known as a ‘test’. Urchin tests are remarkably beautiful, especially seen in sunlight. Here are 2 examples I photographed a while ago. You’ll immediately notice the delicate colours and the amazing complexity of the pattern and symmetry. The top one is (or is most like) a long-spined urchin test.
 
 
Long-spined sea urchin Test / Skeleton Diadema antillarum (Keith Salvesen / Rolling Harbour) Long-spined sea urchin Test / Skeleton Diadema antillarum (Keith Salvesen / Rolling Harbour)

A BIT ABOUT SYMMETRY

Sea urchins are born with bilateral symmetry – in effect, you could fold one in half. If you wear gloves. As they grow to adulthood, they retain symmetry but develop so-called ‘fivefold symmetry’, rather as if an orange contained 5 equal-sized segments. The graphic above gives a good idea of how the interior is arranged inside the segments.

Long-spined sea urchin Diadema antillarum (Melinda Rodgers / Dive Abaco)

A FEW FACTS TO HAND DOWN TO YOUR CHILDREN

  • Urchin fossil records date the species back to the Ordivician period c 40m years ago
  • In the ’90s the population was decimated and still has not recovered fully
  • Urchins feel stress: a bad sign that the spines here are white rather than black
  • Urchins are not only warm water creatures: some kinds live in polar regions
  • Urchins are of particular use in scientific research, including genome studies
  • Some urchins end up in aquariums / aquaria, where I doubt the algae is so tasty
  • Kindest not to prod or tread on them
  • Their nearest relative (surprisingly) is said to be the Sea Cucumber 

Sea Cucumber (Melinda Riger / G B Scuba)

ARE THEY EDIBLE?

They are eaten in some parts of the world, but only where the gonads and roe are considered a delicacy. Personally, I could leave them or leave them.

CREDITS: Melinda Rogers / Dive Abaco (1, 2, 3, 6, 9) taken Abaco; Melinda Riger / G B Scuba (4, 10, 11) taken Grand Bahama; Keith Salvesen / Rolling Harbour (7, 8) taken Abaco; Wiki graphic (5) CC . RESEARCH Fred Riger for detailed  information; otherwise magpie pickings… This is an archive post

Long-spined sea urchin Diadema antillarum (Melinda Riger / G B Scuba)

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ABACO’S 38 WARBLER SPECIES: AN ILLUSTRATED ID GUIDE


 

 

ABACO’S 38 WARBLERS: AN ILLUSTRATED ID GUIDE

The great winter migration of warblers and their arrival in The Bahamas is underway. Reports are appearing – the latest being the Northern Parula.  They will have made long journeys – hundreds of miles – and in the spring they will wing their way home for the summer. On Abaco, 38 warbler species are recorded for the main island and the cays, the latest being the first sighting of a Canada Warbler in 2018.  Since Dorian the situation has undoubtedly been different, especially with the transients and rare species. The 5 permanent resident warbler are still resident. Sighting records of the winter visitors have been scarce. Many migrants and transients have not been recorded since Dorian, and the rarest perhaps never will be. The hope must be that at least the most common winter warblers will continue to arrive, and in increasing numbers.

Yellow Warbler at sunrise.Abaco Bahamas.6.13.Tom Sheley copy copy

First-ever Canada Warbler for Abaco & the entire Bahamas: Aug 2018 (Chris Johnson)

Canada Warbler, Abaco Bahamas (1st record) (Chris Johnson)

Yellow Warbler at sunrise.Abaco Bahamas.6.13.Tom Sheley copy copy

This guide divides the 38 species into categories, with a code for each bird to show:

  • Resident status – permanent / breeding, migratory or transient
  • Frequency – likelihood of seeing each species in its season, rated from 1 (very likely) to 5 (extreme rarities, maybe recorded only once or twice since c1950 when recording began)
Bahama Warbler (endemic), Abaco Bahamas (Alex Hughes)

Bahama Warbler (endemic), Abaco Bahamas (Alex Hughes)

Numerically, the division breaks down into 3 categories of warbler:

  • 5 permanent residents (PR) that breed on Abaco (B), of which two are ENDEMIC
  • 21 winter residents (WR) ranging from ‘everyday’ species to extreme rarities like the very vulnerable Kirtland’s Warbler that needs a specific winter habitat that Abaco can provide 
  • 11 transients, most of which you will be very lucky to encounter
Palm Warbler, Abaco Bahamas (Nina Henry)

Palm Warbler, Abaco Bahamas (Nina Henry)

The photos that follow show an example of each warbler, where possible both (1) male and (2) taken on Abaco. Where I had no Abaco images – especially with the transients – I have used other mainstream birding resources and Wiki. All due credits at the foot of the post.

Bahama Yellowthroat, Abaco Bahamas (Gerlinde Taurer)

Bahama Yellowthroat, Abaco Bahamas (Gerlinde Taurer)

 

AN ILLUSTRATED GUIDE TO ABACO’S WARBLERS

Yellow Warbler at sunrise.Abaco Bahamas.6.13.Tom Sheley copy copy

5 PERMANENT RESIDENTS

BAHAMA YELLOWTHROAT Geothlypis rostrata PR B 1  ENDEMIC

Bahama Yellowthroat, Abaco (Charles Skinner)

BAHAMA WARBLER Setophaga flavescens PR B 1  ENDEMIC

Bahama Warbler - endemic Abaco Bahamas (Alex Hughes)

YELLOW WARBLER Setophaga petechia PR B 1

Yellow Warbler, sunrise, Abaco Bahamas (Tom Shelley)

OLIVE-CAPPED WARBLER Setophaga pityophila PR B 1 

Olive-capped Warbler, Abaco (Bruce Hallett)

PINE WARBLER Setophaga pinus PR B 1 

Yellow Warbler at sunrise.Abaco Bahamas.6.13.Tom Sheley copy copy

WINTER RESIDENTS  (COMMON)

OVENBIRD Seiurus aurocapilla WR 1 

OVENBIRD_Bahamas-Great Abaco_6639_Ovenbird_Gerlinde Taurer 2

WORM-EATING WARBLER Helmitheros vermivorum WR 2 

Worm-eating Warbler.Bahama Palm Shores.Abaco Bahamas.Tom Sheley

NORTHERN WATERTHRUSH  Parkesia noveboracensis WR 1 

BAHAMAS - Northern Waterthrush - Oct 2010 Becky Marvil

BLACK-AND-WHITE WARBLER Mniotilta varia WR 2 

Black & White Warbler, Abaco - Bruce Hallett

COMMON YELLOWTHROAT Geothlypis trichas WR 1 

Common Yellowthroat.Gilpin Pond.Abaco Bahamas.Tom Sheley copy

AMERICAN REDSTART  Setophaga ruticilla WR 1 

Bahamas-Great Abaco_6334_American Redstart_Gerlinde Taurer copy

CAPE MAY WARBLER Setophaga tigrina WR 1 

Cape May Warbler (m), Abaco - Bruce Hallett

NORTHERN PARULA Setophaga americana WR 1 

Northern Parula, Abaco - Woody Bracey

BLACK-THROATED BLUE WARBLER Setophaga caerulescens WR 2 

Black-throated Blue Warbler (m), Abaco - Bruce Hallett

PALM WARBLER  Setophaga palmarum WR 1 

Palm Warbler, Abaco - Peter Mantle

YELLOW-RUMPED WARBLER Setophaga coronata WR 2 

Yellow-rumped Warbler, Abaco - Keith Salvesen (RH)

YELLOW-THROATED WARBLER Setophaga dominica WR 1 

Yellow-throated Warbler, Abaco - Bruce Hallett

PRAIRIE WARBLER Setophaga discolor WR 1 

Bahamas-Great Abaco_6609_Prairie Warbler_Gerlinde Taurer copy 2

Yellow Warbler at sunrise.Abaco Bahamas.6.13.Tom Sheley copy copy

 WINTER RESIDENTS  (UNCOMMON TO RARE)

LOUISIANA WATERTHRUSH Parkesia motacilla WR 3 

Louisiana waterthrush William H. Majoros WIKI

BLUE-WINGED WARBLER Vermivora cyanoptera WR 3

Blue-winged Warbler, Abaco (Becky Marvil)

Blue-winged Warbler. talainsphotographyblog

SWAINSON’S WARBLER  Limnothlypis swainsonii WR 4 

Swainson's Warbler, Abaco - Bruce Hallett

NASHVILLE WARBLER Oreothlypis ruficapilla WR 4 

Nashville Warbler, Abaco - Bruce Hallett

HOODED WARBLER Setophaga citrina WR 3 

Hooded Warbler, Abaco Bahamas (Chris Johnson)

KIRTLAND’S WARBLER Setophaga kirtlandii WR 4 

Kirtland's Warbler (m), Abaco - Woody Bracey

MAGNOLIA WARBLER Setophaga magnolia WR 3 

Magnolia warbler, Abaco - Craig Nash

BLACK-THROATED GREEN WARBLER Setophaga virens WR 3 

Black-throated Green Warbler - talainsphotographyblog

Yellow Warbler at sunrise.Abaco Bahamas.6.13.Tom Sheley copy copy

TRANSIENTS

PROTHONOTARY WARBLER Protonotaria citrea TR 3 

Prothonotary Warbler, Abaco - Ann Capling

TENNESSEE WARBLER Oreothlypis peregrina TR 4 

Tennessee Warbler Jerry Oldenettel Wiki

ORANGE-CROWNED WARBLER  Oreothlypis celata TR 4 

Orange-crowned Warbler dominic sherony wiki

CONNECTICUT WARBLER Oporonis agilis TR 4 

Connecticut Warbler Central Park NYC 10000birds.com

KENTUCKY WARBLER Geothlypis formosa TR 4 

Kentucky_Warbler Steve Maslowski wiki - Version 2

BAY-BREASTED WARBLER Setophaga castanea TR 4 

Bay-breated warbler MDF Wiki

BLACKBURNIAN WARBLER Setophaga fusca TR 4

CHESTNUT-SIDED WARBLER Setophaga pensylvanica TR 4

Chestnut-sided Warbler talainsphotographyblog - Version 2

BLACKPOLL WARBLER Setophaga striata TR 3 

Blackpoll Warbler avibirds.com

WILSON’S WARBLER Cardellina pusilla TR 4 

Wilson's Warbler Michael Woodruff wiki

YELLOW-BREASTED CHAT Icteria virens TR 4 

Yellow-breasted Chat Emily Willoughby wiki

PHOTO CREDITS (1 – 37) Bruce Hallett (Header, 3, 9, 12, 14, 17, 21, 22); Tom Reed (1, 4); Cornell Lab (2); Tom Sheley (7, 10); Alex Hughes (5); Gerlinde Taurer (6, 11, 18);  Becky Marvil (8, 20a); Woody Bracey (13, 24); Peter Mantle (15); Keith Salvesen (16); William H. Majoros wiki (19); talainsphotographyblog (20b, 26, 34); Charmaine Albury (23); Craig Nash (25); Ann Capling (27); Jerry Oldenettel wiki (28); Dominic Sherony wiki (29); 10000birds (30); Steve Maslowski wiki (31);  MDF wiki (32, 33); Avibirds (35); Michael Woodruff wiki (36); Emily Willoughby wiki (37)

CHECKLIST based on the complete checklist and codes for Abaco devised by Tony White with Woody Bracey for “THE DELPHI CLUB GUIDE TO THE BIRDS OF ABACO” by Keith Salvesen