News, Events and Wildlife Sightings at Cemlyn
Last updated 06 July 2008

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Wardens Monthly Report for June 2008

This years wardens are Trudi Clarke and Dawn Wilde.

Tern Colony
Goose excrement was noticed on both islands during the nest count on May 31st. Following this the wardens were successfully able to deter large numbers of Greylags and Canada Geese from roosting on or near the islands by patrols after dusk. These patrols also revealed the night-time presence of herons and these were also scared off, sometimes using a powerful catapult but most effectively at night with powerful torches aided by a modern night scope. Regular night-time patrols were carried out by the wardens assisted by a number of volunteers. Up to 3 herons were regularly seen around the colony but there were days and nights when no birds were present.

Our strategy was to remain on the shingle until too dark to make out individual birds even with torchlight, then to return at 3:30am when the light returned. The acquisition of more powerful torches along with a modern night vision scope made a big difference to our ability to repel the heron(s). With the new equipment, the dark hours were also covered. We took care to arrive and leave at different times to prevent the herons learning a pattern. The torchlight unfortunately, also caused disturbance amongst the terns and black-headed gulls but this was unavoidable. A heron decoy to deter the herons had very limited success. A scarecrow was built (named 'Hollow Iolo') and placed on the ridge in the hope that a constant human presence might keep the herons off. It is moved about every day but cannot stand up to high winds.
Discussions with some of the other Sandwich tern colonies in the UK revealed no major increases in numbers there.

On 11th June a second colony count revealed the extent of the problem caused by predation and associated disturbance. The Sandwich tern area on the Main Island contained only predated eggshells. No chicks were found. This meant that despite a human presence on the ridge, every night, for the majority of the night, since 31st May, the Main Island colony had still suffered 100% losses. The New Island colony may have escaped such heavy predation due to being more closely packed together, or closer to the ridge (and therefore to people), or having more vegetation for chicks to hide in - or a combination of the above.
On 19th June there were over 150 Comics along with 10 or so Sandwich terns on the Main Island. And from 23rd June onwards the numbers of Comics fluctuated but most do seem to be breeders rather than migrators. They were behaving more like a colony - bringing in fish, mobbing people on the ridge and generally making lots of noise. On 24th June a half-grown Sandwich tern chick was spotted on Main Island
By 30th June approximately 50 incubating adults 'Comic' were present.

Black Headed Gull
The first chicks hatched around 29/05/08 and became immediate targets for a Great Black-backed Gull and a Herring Gull (which we suspected was one of the pair which had pestered the new island during May).
No BHGs were seen predating terns eggs or chicks on either island but it is highly probable that this happened a few times. The BHGs are often seen stealing fish from terns.

From 1st to 17th June, chick numbers oscillated between 11 and 28 due to predation/new hatches/uncounted hidden ones. The GBBG and the HG were taking at least 2 chicks each per day. The netting along the top of Bryn Aber wall was 100% effective - we did not see a single gull or other predator perch on the netted portion. However, the tall back wall was used frequently by the GBBG as a resting place between attacks.

On 4th June, the HG received damage to the secondaries on its left wing from BHGs. This marker meant that we could be certain it was the same bird preying on BHG chicks over and over again. We harassed it with catapults whenever we saw it hanging around the weir and the Coalshed but it never went far. This constant vigilance and harassment does seemed to have modified the behaviour of the predatory gulls.
By end of month 45 fledglings were present.

Bird Census
Species of interest include:
American Golden Plover
Little Tern
Roseate Tern
Common Gull
Pale-bellied Brent Goose
Chough
Lapwing flock

Butterfly Transects
Generally windy weather has prevented many transects but two were carried out as below:

08/06/08 - Common Blue, Large White, Meadow Brown, Orange Tip, Peacock

14/06/08 - Gatekeeper, Large White, Meadow Brown, Small Tortoiseshell, Small White

Mammals: Brown Hare; Grey Seal; Harbour Porpoise; Bottlenose Dolphin; Red Fox; Stoat; Pipistrelle Bat; Pygmy Shrew; Common Shrew; Rabbit; Brown Rat; Hedgehog.

Reptiles: Adder.

Amphibians: Common Toad; Common Frog.

Fishes: Dogfish; Eel; Sand eel; Rockling.

Invertebrates: Bloody-nose beetle; Cinnabar moth; Blue-tailed damselfly; Emerald damselfly, Large Red damselfly; Harvestman spider.
In the 07/06 Moth Trap: Small Angle Shade; Lychnis; White Ermine; Spectacle; Small Square-spot; Elephant Hawk; Small Elephant Hawk; Bright-line brown-eye; Silver Ground Carpet; Garden Carpet; Flame Shoulder; Heart & Dart
In the 14/06 Moth Trap: Angle Shade; Setaceous Hebrew Character; Marbled Coronet; Lychnis; White Ermine; Buff Ermine; Spectacle; Bright-line brown-eye; Heart & Dart; Magpie; Shoulder-striped Wainscot; Red Carpet; Barred Straw; Mullein Wave; Square-spot Rustic
In the 29/06 Moth Trap: Garden Tiger; Peppered; Large Yellow Underwing; Dark Arches; Small Magpie; Mullein Wave; Flame Shoulder; Lackey; Heart & Dart; White Ermine; Brimstone; Snout; Spectacle; Wainscott spp.; Buff Ermine; Lychnis; Bright-line Brown-eye; Light Arches; Shark; Clay and a Caddisfly

Rocky Shore transect
A number of rocky shore transects have also been carried out.

Litter
4 black bin-liners of rubbish collected.

Visitors and Donations
978 visitors during June.