A report on

the 2001 breeding season

at the

Little Tern colony

Beacon Lagoons Nature Reserve

Easington, East Yorkshire

Martin G Stoyle

October 2001

 This project was sponsored by English Nature and the South Holderness Countryside Society and was managed by Spurn Bird Observatory Trust

Contents

1.      Summary

2.      Acknowledgements

3.      Weather

4.      The Little Tern colony month by month

5.      Historical breeding success

6.      Wardening and visitors

7.      Reserve management

8.      Protection against predators

9.      Predators

10.    Ringing and colour ring sightings

11.    Discussion

12. Other bird species at Beacon Lagoons Nature Reserve
 

1. Summary

The first Little Tern arrived back at the Lagoons on the 20th of April. The number of terns was still on the low side at the start of the warden’s contract on the 11th May, with only 30 birds present. Courtship was prolonged, and the first terns weren’t on eggs until the 28th May. By the end of May there were only 5 breeding pairs.

The number of pairs gradually built up to a maximum of 44 breeding pairs on the 19th June, which was also the same day the first chicks hatched. By the end of June a total of 19 chicks had hatched. A lack of predators in the area at this time saw all the chicks still present at the end of June. Human disturbance was also light for the vast majority of the time.

The number of hatched chicks had increased to 28 by the 2nd July. However the appearance of a female Kestrel, signalled what was to be the end of the colony in 2001. Over the next week and a half the Kestrel decimated the colony, taking most, if not all, of the unfledged Little Tern chicks. Two chicks fledged on the 15th and left with the remaining adults. A third juvenile was seen in front of Beacon Ponds hide on the 26th, being the last bird to fledge. Two Little Terns at Beacon Ponds on the 28th were the last to be seen in the area.

This represents the worst season since 1997 for the Easington Little Tern colony.

 2. Acknowledgements

Many thanks to English Nature and the South Holderness Countryside Society for providing the project funding and to Spurn Bird Observatory Trust for managing the project. Without the support of these organisations the project would not have been possible in 2001.

Thanks also to Craig Ralston and the volunteers at York University, for giving up their time to help with the fencing, and also for providing a vehicle to move materials to the reserve.

The protection scheme couldn’t continue without volunteers, who help out with wardening and the many practical tasks undertaken around the reserve. Many thanks to Betty Smallwood, Frank Kennington, and Michael and Adam Stoyle, for wardening and to Liz Walters and Paul Massey for their invaluable assistance with many practical tasks throughout the season.

Thanks also to Barry Spence for ringing the tern chicks, and giving me lots of helpful advice, which made my job a great deal easier.

3. Weather

May

The weather during May was generally warm and sunny, with occasional heavy showers, but no prolonged periods of heavy rain. The winds were generally from the northerly quarter during the first fifteen days of the month, and then from the southwest until the month’s end.

June

June started with strong northerly winds building to gale force by the 2nd, backing to the westerly quarter by the 3rd and then dropping to force 2-4 (Beaufort scale) until the 12th. They then veered southeast until the 20th, before returning to northerlies until the month’s end. Hot humid weather prevailed throughout the month.

July

Light winds dominated the month coming mainly from the northwest and southeast. It was a generally sunny month with occasional heavy showers.

4. The Little Tern colony month by month

April

There was little coverage of the site during the month as the Little Tern warden had yet to begin his contract. The first Little Terns arrived back at the site on the 20th, with numbers staying in low single figures until the month’s end. Two Little Terns were displaying over the Lagoons on the 28th.

May

The Little Tern warden started on the 11th. Many Little Terns were now in full display, though numbers fluctuated greatly, with between five and forty birds present. The first pairs were noted nest prospecting on the 20th, with seven pairs nest scraping on the 22nd. Two pairs were seen to be incubating on the 28th, with six pairs sitting on the 30th.

Up to eighty-nine Little Terns were present intermittently by the end of the month. These were mainly seen, and counted, whilst roosting on the beach. Two Carrion Crows were making frequent visits to the colony during the last ten days of the month, which caused some concern as the Little Terns did not easily drive them off.

June

The month began with a strong northerly gale, which combined with high spring tides, caused concern for the terns that were incubating. However the sea didn’t breach the low dunes, thus never flooding the breeding area. Large amounts of sand were blown through the colony, causing two of the incubating pairs to desert their nests. These were subsequently covered with sand. Four pairs that were nest prospecting on the beach to the south of the area, decided to abandon the area, and a few days later were seen prospecting in the traditional breeding area.

The number of sitting birds increased daily over the next two weeks. Disturbance was relatively light during this period, although two Carrion Crows were still visiting the area. However with an increased number of incubating pairs, these were easily driven off. A freshly laid egg found almost intact at the side of the lagoons on the 12th, had been removed from its nest by a male Little Tern, that had been displaying to a female that had already laid. Progress continued smoothly and by the 14th there were 35 breeding pairs, rising to 41 by the 15th. The weather had been kind throughout most of June with light winds mainly from the southern quarter. This combined with a lack of predators made for good breeding conditions and the first four chicks hatched on schedule on the 19th. This was also the day the number of breeding pairs reached a maximum of 44.

The number of hatched chicks increased almost daily and by the month’s end 15 chicks were present, including one bird that had been incubated for 29 days! Fox tracks were found around the colony, though no evidence of chick predation was noted. The good weather continued and everything was looking conducive for a successful breeding season.

July

The 1st saw four more chicks hatch. Human disturbance on this date was high and the adult Little Terns wouldn’t land for long to feed their chicks. At least four Little Tern chicks were attacked by adult Ringed Plovers in the afternoon, when the tern chicks wandered into their territory. The number of chicks increased again on the 2nd to 23.

The appearance of a female Kestrel at around 4pm, on the 2nd, was to spell the end for the colony. By the end of the day the Kestrel had made five more visits, predating a chick on each occasion, and leaving to the northwest. Little Tern activity was much reduced on the 3rd; the Kestrel had predated over 20 chicks in less than 24 hours!

Over the next five days the Kestrel completely decimated the colony taking over 70 chicks and often making over twenty visits a day. The method of predation was more akin to Merlin or Sparrowhawk. The bird would sit on Long Bank watching, before attacking low and fast directly into the colony, then making off quickly with the predated chick. The Little Terns seemed completely unable to defend against this style of hunting. Even when the Kestrel was flushed by the warden she would usually return within half an hour.

By the 8th the number of Little Terns in the area was much reduced. Although some had started displaying again, it was a rather half-hearted affair, involving high level chasing but no fish passing. On the 10th, hope for some chicks still being alive was fuelled by the sight of two Little Terns hovering with fish over the area of dunes to the north of the colony. The fish was just dropped into the dunes, with the adult terns quickly flying away. This was presumably done so as not to give away the precise location of their chicks. Late in the afternoon, of the 10th, two juveniles were seen on the beach. Over the next few days these birds were seen making short flights around Beacon Ponds. After a particularly heavy shower on the 11th a reasonable sized Little Tern chick was found well down the beach in a pool of water. Although cold it seemed relatively all right, and after been warmed up was returned to the dunes.

The juvenile Little Terns left the area on the 15th and were not seen again. On the 26th another juvenile Little Tern was seen in front of Beacon Ponds hide with one adult. This was the last bird to fledge, and they were also the last Little Terns seen in the area. This bought to a close what had started out a very promising breeding season.

5. Breeding success of Little Terns at Easington 1977 to 2001

6. Wardening and visitors

Most daylight hours were covered, either by the warden or by a small group of volunteers. The public in general caused little disturbance to the terns. There were 26 incursions into the colony during the breeding season, all of which were by people who claimed to have not seen or misinterpreted the warning signs. These were always resolved quickly once the situation was explained. 

7. Reserve management

Fencing

The perimeter fence that surrounds the reserve during the breeding season was erected on the 2nd May, and taken down on the 5th August after the colony had dispersed from the area.The main function of this fence is to act as a visible deterrent to the general public, used in conjunction with breeding bird signs. This dramatically cuts down on incursions, by the public, into the breeding area.

Electric Fencing

The electric fence that surrounds the traditional breeding area was erected on the 1st June and removed at the end of July. The main function of this fence is to protect against terrestrial predators, such as foxes, which mainly hunt at night when the reserve is unmanned. It also helps to keep people out of the main breeding area, who have inadvertently wandered into the boundaries of the colony.

Hide maintenance

Both the hide at Beacon Lagoons, and the tern wardens hut, have fallen into a bad state of repair over the last few years, so it was decided that some long over due maintenance needed to be undertaken.Both buildings were painted whilst the Beacon Lagoons hide received some new wooden plank screens. These replaced the original reed screens which were now dilapidated and beyond repair.

Tern Rafts

During the first part of the warden’s contract the Common Tern rafts, which are usually positioned on Beacon Lagoons, had broken free from their moorings the previous winter and were laying in a bad state of repair. These were repaired and repositioned, attracting two pairs of Common Terns, which bred. However they both failed to fledge any chicks.   

8. Predator protection measures

Electric Fence

Once again an electric fence was erected around the main breeding area. This is to protect against terrestrial predators such as foxes. No Little Tern losses were thought to occur through terrestrial predators. This was thought to be a direct result of the electric fence.

Chick Shelters

During the 2001 breeding season three different types of chick shelters were used.

Plastic Pipes - These were basically laid on the ground with a covering of sand in the bottom of the pipe. These were not used by the chicks at all during the 2001 season. This method has been used at Easington for several years, without very much success. However other colonies have achieved good results using this type of shelter.

Wooden Shelters - These are basically wooden tunnels, around three feet long, and one foot wide. Chicks were seen to use these on a regular basis, in hot sunny weather, and also in high wind and rain. These were the most often used and effective type of shelter.

Natural Shelters - These shelters were made from natural resources at hand. Flat pieces of stone or wood were propped up on large rocks, to create a small tunnel. These were also used by the terns on a regular basis, again to protect against avian predators, and also against rough weather. These were probably used as often as the wooden shelters, though it was hard to monitor exact use without causing too much disturbance to the colony.

Discussion    

The use of an electric fence is obviously a great way of keeping terrestrial predators out of the colony. Easington Little Tern chicks seem to favour natural wooden shelters as opposed to plastic pipes, so a greater number of this type of shelter should help prevent losses from bad weather and avian predators in future years.

Further work to investigate alternative shelters should be undertaken.

9. Predators

The following ground and avian predators were recorded in, or near, the colony during 2001.

Fox

Fresh fox tracks were found on a number of occasions throughout the breeding season, though no evidence of predation was found. This lack of tern predation was probably due to the large numbers of rabbits in the general area, providing a readily available food source. The foxes therefore had no need to resort to predating the Little Tern colony.

Stoat and weasel

Stoat or weasel tracks were found on a number of occasions, with just one confirmed sighting of a stoat on the 28th June. No known losses occurred to this species in 2001

Sparrowhawk

The only sighting was of a male flying south over Long Bank on the 12th June.

Kestrel

Sporadic sightings of Kestrels were seen during the early breeding season, though these didn’t cause a huge amount of disturbance. The appearance of an adult female on the 2nd of July was to spell the end for the colony in 2001. The Kestrel often made twenty visits per day, taking seventy-five chicks over a two-week period. Some Little Tern chicks were even predated only minutes after hatching.

This has been the worst year ever for Kestrel predation at the Easington colony, after suspected predation during the 2000 breeding season. The predation in 2001 was probably down to just one individual. The problems caused by Kestrel predation will have to be addressed in future years, if Easington is to remain a major Little Tern colony.

Hobby

During the first half of June several visits were made to the colony by this species. Though they caused a huge amount of disturbance, no actual chasing was undertaken, and fortunately no adult terns were lost, as they have been in the past.

Carrion Crow

Up to four birds were present throughout the season, mostly frequenting the Long Bank area. Any birds straying into the colony were quickly seen off by the Little Terns. No losses were due to this species during the 2001 breeding season.

Barn Owl

Two birds were regularly present around the Long Bank area during the breeding season. These seemed to pose no threat to the Little Terns, and any prey items observed were always small voles. Fortunately they never found the easy source of food only a few yards away. No losses were due to this species during the 2001 breeding season.

Grey Heron

These never posed a really serious threat to the colony, but whenever one came near they were mobbed constantly until well out of the area. No losses were due to this species during the 2001 breeding season.  

10. Ringing and colour ring sightings

A total of 23 Tern chicks were ringed using the Easington colour rings (mauve). These were placed on the left leg, with a standard BTO metal ring on the right leg. The colour ringing scheme was suspended with the arrival of the female Kestrel.

All visits into the colony were covered by schedule 1 licenses issued by English Nature.

Colour ringed birds

Sightings of colour-ringed birds from other colonies were frequent throughout the season. Three pairs from other colonies bred at Easington. These were a pair with red rings on their left legs, two pairs with blue rings on their left legs, and a pair with green rings on their left legs.

Colour ring sightings

Apart from the breeding birds mentioned above, these were as follows-

14th May          Four birds with blue rings.

14th May          One bird with a green ring.

15th May          Two birds with blue rings.

15th May          One bird with a red ring.                                 

19th May          One bird with a blue ring.

19th May          One bird with a green ring.

20th May          One bird with a blue ring.

26th May          One bird with a blue ring.

30th May          One bird with a blue ring.

20th June         One bird with a mauve ring.

 Key to Little Tern colour ring colours

11. Discussion

There was a drop in the number of breeding pairs from the last two years, which is strange considering the amount of suitable breeding habitat, especially to the south of the tern wardens hut. However a more pressing issue is the presence of the female Kestrel, which decimated the colony. This bird is also thought to have probably predated several chicks during the 2000 season.

Proposals

The area to the south of the tern hut was used this season, though not to the extent it could have been. To encourage further pairs, breeding decoys and sound recordings of displaying birds, could be used, as suggested in previous years. This could increase the chances of breeding success and hopefully encourage a greater number of breeding pairs.

The threat from avian predators could be minimised by placing a Common Tern raft on the lagoon adjacent to the main breeding area. Common Terns are much more veracious at protecting their eggs and young, and are much more likely to drive away falcons, such as Kestrels and Merlin's.

12. Other birds at Beacon Lagoons

The following species listed as birds of conservation concern by the RSPB were also recorded at Beacon Lagoons during the project.

In addition to breeding birds, Beacon Lagoons are also an important area for roosting waders, terns and wildfowl whilst on passage.

Shelduck

Up to 11 birds were seen regularly until the end of May. Shelduck is an RSPB Bird of Conservation Concern (BOCC) on the Amber list (BL, WI, WL).

Wigeon

A male and female were present all summer though no evidence of breeding was noted. Wigeon is a BOCC on the Amber list (WI, WL).

Teal

A large flock comprising 53 birds was noted on the 5th August on Beacon Ponds. Teal is a BOCC on the Amber list (WI).

Scaup

A single male was on Beacon Ponds from the 1st until the 4th August. Scaup is a BOCC on the Amber list (BR, SPEC2&3).

Goldeneye

A single male was on Beacon Ponds on the 28th July. Goldeneye is a BOCC on the Amber list (BR, WL).

Kestrel

Regular but sporadic sightings of Kestrel were noted throughout the Little Tern breeding season, mainly hunting over the fields at the northern end of the reserve. Sightings became more frequent with the arrival of the rogue female that was breeding in nearby Easington. Kestrel is a BOCC on the Amber list (BDM, SPEC 2&3).

Oystercatcher

Five pairs bred within the reserve boundary, with the maximum number of passage birds peaking at 62 on 16th August. Oystercatcher is a BOCC on the Amber list (BI, WL).

Grey Plover

Small numbers were seen on passage in spring. Autumn passage started from mid-July with numbers peaking in the low 20s during mid-August. Grey Plover is a BOCC on the Amber list (WI, WL).

Dunlin

Small numbers were seen on passage in May. Autumn passage migrants were noted from early-July, building up to a peak of 5000 by late-August. Dunlin is a BOCC on the Amber list (WI, WL, SPEC 2&3).

Ruff

Two summer plumaged males were present on the 27th and 28th July. Ruff is a BOCC on the Amber list (BR, WL).

Bar-tailed Godwit

A maximum count of 34 on the 17th August. Bar-tailed Godwit is a BOCC on the Amber list (WI, WL, SPEC 2&3).

Redshank

Regularly seen roosting on Beacon Ponds from early-July with numbers exceeding 8000 towards the end of August. Redshank is a BOCC on the Amber list (WI, SPEC 2&3).

Greenshank

Regularly seen feeding at southern end of Beacon Ponds from mid-July, with a maximum of 17 on 21st August. Greenshank is a BOCC on the Amber list (BL).

Little Gull

Large flocks of up to 70 birds regularly visited Beacon Ponds during August. Little Gull is a BOCC on the Amber list (BR, SPEC 2&3).

Sandwich Tern

Large numbers roosted on Beacon Ponds from mid-July, with up to 3000 present on most days in August. Sandwich Tern is a BOCC on the Amber list (BL, SPEC 2&3).

Sand Martin

A pair nested for the first time within the reserve boundaries, successfully fledging two young. Sand Martin is a BOCC on the Amber list (SPEC 2&3).

Skylark

Eight pairs nested within the reserve boundary. Skylark is a BOCC on the Red list (BD).

Tree Sparrow

Up to 30 birds were seen regularly at the northern end of the reserve. Tree Sparrow is a BOCC on the Red list (BD).

Linnet

Two pairs bred, and up to 50 birds were regularly seen at the northern end of the reserve. Linnet is a BOCC on the Red list (BD).

Reed Bunting

A pair bred and two other birds were present from the end of June. Reed Bunting is a BOCC on the Red list (BD).

Corn Bunting

A pair bred raising two young, with an additional three birds present from mid-August. Corn Bunting is a BOCC on the Red list (BD, HD). 

RSPB Birds of Conservation Concern (BOCC)

Red list criteria

BD = >50% decline of the UK breeding population, or range, over the previous 25 years.

HD = Historical population decline in the UK between 1800-1995.

Amber list criteria

BDM = a moderate decline (25-49%) in the UK breeding population, or range, over the previous 25 years.

BR = five year mean of 0.2-300 breeding pairs in the UK.

WI = >20% of European breeding population in the UK.

BL = >50% of the UK breeding population can be found in 10 or fewer sites, but not BR.

WL = >50% of the UK non-breeding population can be found in 10 or fewer sites.

SPEC 2&3 = species with an unfavourable conservation status in Europe.