• Sim Elliott

Two Loons in Eastbourne: Black-Throated & Great Northern Divers in the Sovereign Harbour. 03.11.21

Updated: Dec 4, 2021

I saw on the BirdGuides App that there was a Black-Throated Diver in the Sovereign Harbour Eastbourne; so I decided to go and see if it was still there. It was, plus a Great Northern Diver and a Guillemot. Another birder I spoke to there said that there had been a Red-Throated Diver there too yesterday, but I did not find it.


The first birds I saw in the Inner Harbour was Cormorant and a Great Black-Backed Gull


I then I saw a Guillemot


As I got closer to the lock gates separating the Inner Harbour to the Outer Harbour (tidal), I saw tht Guillemot and the Black-Throated Diver (winter plumage) - here with a Herring Gull


Black-Throated Driver (aka Arctic Loon (US/Canada)

These streamlined diving birds sit low in the water and dive with consummate ease. On land they are clumsy, barely able to walk with their legs so far back on their bodies.


They are easily disturbed when breeding and their vulnerability to marine pollution make them a vulnerable as well as rare breeding species. They are listed as a Schedule 1 species on The Wildlife and Countryside Act.


Black-throated divers can be seen in Scottish Highland lochs in summer and around sheltered coasts in winter, but rarely along Irish Sea coasts. Moray Firth and W coast of Scotland best in winter, as well as the NE and SW coasts of England. Sometimes seen at inland reservoirs.


Population:


UK breeding: 200 pairs; UK wintering: 560 birds Black Throated Diver Facts | Gavia Arctica - The RSPB


Black-Throated Diver with Guillemot


The black-throated diver is a large waterbird: larger than the great crested grebe but smaller than the cormorant in size. They look smart in their summer plumage, with a black throat, silky grey head and neck, and a black and white-chequered back. In the winter, black-throated divers turn a very dark grey above and white below, with an obvious white patch on their rear flanks. They have a straight, dagger-like bill.


Behaviour


Black-throated divers nest on small pools and lochs in the far north of Scotland. In the winter, they can be seen on the sea around most coasts where they feed on fish. They also sometimes nest or overwinter on big lakes and reservoirs. Most black-throated divers search for food alone, although some small groups do gather during winter to feed together.


Distribution


Can be seen on most UK coastlines, but more common in the north-west of Scotland including the Hebrides, Orkney and Shetland.


Facts


The black-throated diver is known in America as the ‘Arctic loon’.

Black-throated divers can fish at depths of up to six metres, but they usually only stay underwater for less than a minute.

Although they are excellent swimmers, black-throated divers cannot walk well on land because their legs are too far back on their body. Black-throated diver – Scottish Wildlife Trust



Great Northern Diver (aka Common Loon (US/Canada) in the Outer Harbour


The largest of the UK's divers, it has a bigger, heavier head and bill than its commoner relatives. It is largely a winter visitor to our shores although some non-breeding birds stay off northern coasts in the summer. Great northern divers are listed under Schedule 1 of The Wildlife and Countryside Act.


UK wintering:2,500 birds


Great northern divers can be found around coasts where it is usually solitary, often farther out to sea than other divers. Occasionally seen inland on reservoirs. Largest numbers off the Northern and Western Isles of Scotland and also the Cornish coast.


Great Northern Diver Bird Facts | Gavia Immer - The RSPB


The great northern diver is a large water bird, which is mostly a winter visitor to the UK. Great northern divers breed in Greenland, Iceland and North America, where they're called common loons. There have been occasional records of them breeding in Scotland, but these are very rare.


They breed on large woodland lakes or pools on tundra, with the male and female working together to build the nest on an island or shoreline. They're excellent swimmers, using their large feet to chase after small fish under the water.


Great northern divers usually spend the winter on the sea, favouring shallow areas close to shore. They can sometimes be seen migrating along the coast singly or in small flocks. Great northern diver | The Wildlife Trusts


All divers are unable to walk or stand on land. Here the Great Northern Diver is pushing itself along on its belly with its feet.


"Rarely observed on land, except for copulation, building or tending of nest, ritual defecation (see Drinking, Pellet-Casting, and Defecation), during or after conspecific conflicts, or when ill or injured. Because much of the proximal hindlimb lies within the body cavity and is not covered directly by skin, movement at the hip and knee and the ability to position the foot below the center of mass are restricted, thus limiting the ability to walk upright on land (208). Upright walking is observed mainly when leaving water to incubate the eggs on nest, likely minimizing the risk of pushing eggs from the nest and allowing the individual to position themselves appropriately on nest. Can be found on land away from the nest (for example, those that may be sick, those that may have been forced from the water onto land following an agonistic interaction with conspecifics, or those that have landed on roads and fields during storms), and may propel themselves forward using their feet and if rushed, wings. In some instances, individuals have moved > 1 km on land. Newborn chicks can walk upright on land, but lose this ability by around week 3. In addition, chicks of various ages that are hatched on small, acidic lakes commonly make land crossings of several hundred meters or more to larger lakes that offer more plentiful food (209)." Locomotion

Cornell Lab of Ornithology, Birds of the World, Common Loon, Gavia immer, Behaviour >Walking, Hopping, Climbing, Etc. accessed on 04.12.21 https://birdsoftheworld.org/bow/species/comloo/cur/behavior#locom


detail


I also saw some beautiful Great Crested Grebes and Cormorants in the Outer Harbour


Great Crest Grebes in the Outer Harbour


Cormorants in the Outer Harbour


A photo graph of the Outer Harbour; not taken by me today; but by Alison Rawson, Sovereign Harbour at low tide cc-by-sa/2.0 - © Alison Rawson - geograph.org.uk/p/1118901


Outer Harbour from the air by Michael Harpur, eOceanic


Today's BirdGuides (East Sussex filter)



Sovereign Harbour at low tide cc-by-sa/2.0 - © Alison Rawson - geograph.org.uk/p/1118901


Photo Michael Harpur, eOceanic

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