The River Liza–Gareth BrowningApril 2015

Bird Monitoring 2015

Dipper Cinclus cinclus – River Liza Survey

Contents

Contents

Introduction and background

Methodology

Survey Results

Dipper Survey of Liza - visit 1 - 07/03/2015

Dipper Survey of Liza - visit 2 - 14/05/2015

Summary of survey results

Comparison with the 2007 survey

Discussion

Summary

Recommendations

Acknowledgements

Appeal for Records

Appendix A - The 2015 Surveys

References, further reading and useful links

Survey Maps

Introduction and background

This report should be read in conjunction with the base line 2007 Dipper Survey Report which can be found on the Wild Ennerdale website on the Monitoring page under the “Birds“ section. The 2007 report details interesting historical background data and explores why dipper is important as an indicator of the general health of upland riverine ecology. Much of this is still relevant, but to avoid repetition will not feature in this report.

The Wild Ennerdale project is committed to long term monitoring of 3 key indicator bird species red grouse, ring ouzel and dipper. These iconic species have been chosen as their presence or absence can give us an insight in to the health of the particular habitats that these specialists inhabit. The first surveys were undertaken in 2007.

White-throated dipper Cinclus cinclus (hereafter referred to simply, as dipper) is most commonly associated with fast flowing shallow upland becks and streams, although it can occur in lowland areas if these conditions prevail and providing the water quality is good enough to support an abundant aquatic invertebrate population.

“Dippers breeding at good quality sites may start as early February, but those at high altitudes and/or near acidic streams start later, lay smaller clutches and rear smaller broods than birds on better quality sites. Pairs also rarely attempt a second brood on these poor quality sites” (RSPB).

The establishment of baseline population data for dipper on the Liza at the outset of the Wild Ennerdale Project, and the selection of dipper as a key environmental indicator species are key parts of the long-term environmental monitoring programme for the project area. It was therefore agreed that a baseline survey of dipper be carried out in the spring of 2007 to reliably estimate the number of breeding pairs and their distribution on the River Liza.

The 2015 Dipper survey on the River Liza will compare its findings with the 2007 survey.

Methodology

To estimate the spring population of dipper present on the River Liza, and to carry this out in a cost effective way, and using the following readily repeatable methodology.

  • Timing – to walk the River Liza once in March and again in May. If birds are located in May, then extra visits may be required to establish whether they are nesting.
  • Weather – the survey may be carried out in most conditions but should avoid heavy rain and strong winds.
  • Location – to walk the length of the Liza starting where the Liza enters Ennerdale Water at 6-figure grid reference NY124144, altitude 113m and ending where the unnamed beck from Beck Head joins the Liza at NY 204115 altitude 360m, a distance in excess of 11km. Keep as close to the banks of the Liza as terrain and undergrowth allow, although it may be impossible to follow the braided river system in its entirety in the vicinity of Low Gillerthwaite.
  • Any dipper sightings to be recorded using British Trust For Ornithology (BTO) standard notation on to a photocopy of an appropriate scaled map as well as recording sightings of other riverine species such as goosander, common sandpiper, kingfisher and grey wagtail.
  • A record to be kept indicating whether the water levels in the river are low, normal or high.
  • If dipper are present, try and establish whether birds are on territory and try to establish if birds are nesting. This may require pausingto be able to study the behaviour of any dipper observed. If no nests are found but foraging adults are present it would be advisable to carry out at least one extra visit to establish whether the bird is a non-breeder.
  • Use a global positioning system (GPS) to record the survey track and all dipper observations as well as any other interesting riverine species. Enter these locations in to the device by way of a unique waypoint number. Download the track log and waypoints on to Memory Map software and store on a personal computer (PC).
  • Make hard copies of each survey map which clearly show the findings.
  • At the end of the survey estimate the number of dipper present and the number of dipper either territorial and/or nesting.

Survey Results

Dipper Survey of Liza - visit 1 - 07/03/2015

(Survey date in 2007was 15/03/2007)

There were 2 records of dipper, involving different individuals:

1) Dipper left boulder at NY158138 and flies downstream.

2) Dipper forages in river at NY169134 and flies downstream.

Other riverine species recorded were:

1) A pair of mallard at NY141131.

Dipper Survey of Liza - visit 2 - 14/05/2015

(Survey date in 2007 was 09/05/2007)

No dipper were recorded on the May survey. As none were present no further survey work was undertaken in subsequent months.

Other riverine species recorded were:

1) Four female goosander resting on a shingle bank - the mouth of the Liza at NY124144.

2) A pair of grey wagtail at the “Low Gillerthwaite” footbridge at NY134141

3) One male grey wagtail foraging in the main channel of the braided river complex opposite High Gillerthwaite.

4) One male grey wagtail foraging in the main Liza channel at NY153139.

5) A territorial pair of grey wagtail on Liza – 230m south of Black Sail YHA at NY195122.

6) 2 pairs of graylag geese in the vicinity of Gillerthwaite.

7) 2 male mallard at Moss Dub at NY146137

Other interesting bird species:

There were 2 registrations of cuckoo in the upper valley beyond the Middle Bridge – heard not seen – see survey map for exact location.

Summary of survey results

07/03/2015 visit 1 – two dipper recorded on the Liza.

14/05/07 visit 2 - no dipper recorded.

See maps 1&2 at the back of the report for survey route and sightings.

Comparison with the 2007 survey

Dipper - Ennerdale– photo Gareth Browning – 21/02/2009

No dipper were recorded on the 2007 March survey, whereas two dipper were recorded on the 2015 March survey. This was promising as birds present in the “breeding season” could be regarded as potential colonisers. The sightings were 1.15km apart and on a stretch of river that looks like good dipper habitat,that is one with plenty of boulders and riffles and with a good gradient. However,as the two sightings were essentially “snapshots” the observer would have had to have been extremely fortunate to witness any significant breeding behavior such as singing, courtship or nest building. All that can be said is that two individuals were seen. Further study over the following days would have been needed to establish whether the birds were a pair or separate individuals. The author has noted that dipper are more likely to be encountered on the Liza in winter and early spring than in the summer. This is likely to correlate with the period of peak biomass with more aquatic benthic insects available at this time prior to the emergence of adult insects (Shaw 1978). It is not known whether invertebrate biomass has significantly increased since the 2007 survey. Breeding dipper numbers strongly correlate with good numbers of invertebrates. However, the presence of two dipper indicates that there are some foraging opportunities, at least enough to sustain small numbers of non-breeding dipper at this time of year.

No Dipper were recorded on the May 2015 survey.

In 2007 a dipper was recorded on the May survey. This sighting was highly promising and triggered a series of subsequent surveys to establish whether dipper were breeding on the Liza. Thesesupplementary surveys failed to find any breeding dipper. However single birds were also seen on the 23/06/2007 and 26/06/2007.

If these sightings had been concentrated on a particular stretch of river this would have been highly indicative of a breeding territory. However, the records were well spread out and dispersed over a 3.6km stretch of river.

Only single birds were ever recorded on any of the 2007 surveys and no breeding behavior such as “carrying food” was observed. It is likely that these observations referred to the same single non-breeding individual, which foraged unchallenged along a long stretch of the Liza.

See map 3 at the end of the report which shows all the locations of sightings from the 2007 and 2015 surveys. All sightings were on a 3.7km stretch of river, ranging from NY147138 in the west (140m asl) to NY 179130 in the east (220m asl). The presence of dipper here would indicate that this stretch of river affords the best foraging conditions. As survey work continues we are slowly defining a core area of dipper activity. It is here where we stand the best chance of establishing breeding dipper and this is where conservation efforts should be focused. It has been shown that nest-boxes and nesting tubes provide protection from flooding and mammalian predation, natural nest sites being vulnerable to both these. Providing a safe nesting and roosting site can significantly boost a dipper population providing there is enough aquatic benthic invertebrate food present.

Discussion

I would refer the reader to the Discussion section of the The Wild Ennerdale report Dipper Cinclus cinclus – survey of the River Liza 2007 which can be found on the Wild Ennerdale website

The effect of water quality and the fact that acidic water holds fewer invertebrates and the implications this has for dipper on the Liza is discussed in the 2007 report. Additionally, it is worth considering the following with regard to recolonisation ofthe River Liza by breeding dipper:

Sedentary nature of adult dipper and dispersal of juveniles

  • “Between 1978 and 1986, 2500 nestlings and 700 fledged Dippers were ringed on rivers in mid and south Wales. Adults showed strong fidelity to breeding sites, only 3.6% (of 138) moving more than 2.5km between breeding attempts. By contrast, 30% (of 166) of birds ringed as nestlings moved more than 5km and up to 32 km from natal sites; post-natal dispersal involved significantly greater distances in females than males, with females significantly more likely to cross watersheds”(Tyler and Ormerod 1990).
  • It is encouraging to see that dipper have now been recorded on both the 2007 and 2015 surveys. The majority of dipper on the River Liza are likely to have dispersed as juveniles from natal sites on the River Ehen. Dipper do breed as “second calendar year birds” and will actively be attempting to establish a territory if conditions are favourable. Essentially many of the birds on the Liza will be one year olds.
  • Nest sites are traditional, and are used by successive generations of birds. One site is said to have been used continuously for 123 years (RSPB)

The importance of aquatic benthic invertebrates

  • “The research over recent years into the Dipper population on the Teme can be compared to the invertebrate monitoring data collected over a similar period. There appears to be a direct correlation between the Dipper numbers in the upper catchment where invertebrate numbers are still good, and the lower Dipper numbers in the lower catchment where invertebrate counts are also poor. A similar picture is revealed when assessing habitat, which not surprisingly is better in the upper catchment compared with the lower catchment. This confirms that the Dipper is a very important indicator species in the health of the river, its ecology and ecosystem” (Tony Bostock, Director Severn River Trust, pers.comm. 2012 from the Dippers Cinclus cinclus In the River Teme Catchment report 2010).

Winter distribution of dipper

  • Ennerdale Water is oligotrophic, that is low in nutrients. Dippers will feed by oligotrophic lake shores especially outside the breeding season (Tyler and Ormerod - The Dippers – 1994). The previous statement is borne out by Wetland Bird Survey (WEBS) data from Ennerdale Water, a monthly survey undertaken by the author to monitor non-breeding waterbirds. It is part of a UK wide scheme run by the BTO. During the course of these surveys dipper are frequently seen foraging along the lakeshore outside the breeding season, but are found less frequently in the breeding season. The author has noted that when the river Ehen is in spate there is more chance of seeing dipper foraging along the lakeside. Presumably lakeside foraging during flood events is easier and more productive than on a deep fast flowing river.
  • Data from “Bird Atlas 2007-11 (BTO)”also illustrates the difference between winter and summer abundance of dipper in Ennerdale. Atlas work for 10 km sq NY11 was carried out by the author (10km sq NY11 does not cover the full area of Ennerdale Water. It covers more than two thirds of the lake’s area and lakeshore;that is everything west of the Northing NY10 that bisects Anglers Crag). Summer survey work found no dipper on the Lake or up the Liza valley, but winter survey work recorded dipper in 4 Lakeside tetrads NY1016, NY1014. NY1214, and NY1212.
  • Dipper are frequently seen on the lake in the winter. A favourite location to see non-breeding dipper is in the bay adjacent to Smithy Beck. This is only 200m from the mouth of the River Liza. The author has seen the odd bird on the Liza in winter, the most unusual record being a dipper recorded foraging at Moss Dub (tetrad NY1412) on 18/01/2009 which was a very surprising location given the stagnant nature of the pond.

Traditional nest site at scout camp footbridge on the River Ehen and its history

  • The closest traditional dipper nest site to the River Lizais on the River Ehen. The nest site is under the footbridge which is located50m west of thelake weir at grid reference NY088153, and is at the very start of the River Ehen. This footbridge will be referred to as the scout campfootbridge from now on.
  • Listed here are some of the more interestingrecords from scout camp footbridge indicating breeding or territorial activity (None of these records are part of a systematic survey and are taken from the authors notebook):-
  • 25/04/2004 – dipper visits nest under bridge.
  • 15/07/2005 – adult dipper with 2 recently fledged juveniles in attendance begging for food.
  • 01/03/2008 – female dipper nest building, and carries nest material to nest under footbridge, male sings nearby.
  • 13/04/2008 – dipper takes food to nest (confirming breeding)
  • 22/03/2009 – dipper leaves nest under footbridge
  • 04/05/2009 – dipper takes food to nest.
  • 11/02/2011 – dipper visits nest site under footbridge.
  • 21/02/2011 – dipper nest building and carries nest material to nest.
  • 13/03/2011 – dipper leaves nest under footbridge.
  • 18/11/2011 – 2 dipper present on river near footbridge, first time here for some considerable time - birds did not successfully breed this year.
  • 18/04/2012 – dipper sings near scout camp footbridge.
  • 25/04/2014 – A pair, one investigates nest site under footbridge
  • 29/04/2014 – dipper leaves nest site under footbridge.
  • 01/06/2014 – 1 present after an absence of 5 weeks – birds didnot successfully breed this year. Note: It is not known whether large scale works to reinstate Ben Gill impacted on breeding success this year, a bird was not noted again until 05/09/2014 and was then regularly present for the rest of the year.
  • 25/02/2015 – dipper pair present, however no activity at the nest site was noted this season – the last time a dipper was seen at this location was a single bird on 01/04/2015. None were seen through the summer and autumn months despite frequent visits - 31 visits from 07/04/2015 to 09/11/2015.

Winter territory at Scout camp footbridge

  • “In Britain many observers have reported dippers showing territorial behavior in the winter. Murphy (1972) found winter territories to be established in September to October and to exist until February or even March. In much of our study area, winter territories are very similar to breeding territories, the two often coinciding, with many pairs remaining on the same stretch of 500-1000m of river for the whole year. There are some single birds during the winter, some of these occurring on rivers where breeding does not occur. On poor quality, acidic streams winter abundances are low, c. 0.25 birds/km; elsewhere in Wales there may commonly be 2-3 birds/km.”(Tyler & Ormerod 1994)

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  • At the scout camp footbridge site, in years when a breeding attempt is short-lived and unsuccessful, birds are often absent through June, July and August withdipper reappearing in the autumn. In 2014 the last record of dipper in the breeding season was 1 present on 01/06/2014, 11 subsequent visits over the summer were made without success until one was seen on 05/09/2014. Dipper were then present on and off throughout the winter with the formation of a pair observed:-
  • 10/11/2014 & 11/11/2014 – dipper sings near scout camp footbridge
  • 19/11/2014 – territorial bonding - 2 birds involved in pursuit flight, is likely to indicate formation of a pair.
  • 27/11/2014 – pair present, birds side by side.

Colonisation of river Liza by dipper from river Ehen

  • As previously noted the scout camp footbridge on the river Ehen is the closest known “traditional nest site” that is within the same watershed as the river Liza. Without extensive systematic surveys in adjoining watersheds it is not known whether there are any nest sites closer to the river Liza and whether colonisation from outside the valleyis at all likely.

The last time fledged dipper were seen by the author at the scout camp footbridge breeding site was in 2005. However successful breeding over the intervening years cannot be totally ruled out as the authors records are of a casual nature.

Logic would dictate that a healthy population on the river Ehen would be fundamental in any recolonisation of the river Liza by dipper.

  • As adult dipper are highly territorial and sedentary in nature, they are not likely to move great distances from a traditional territory, therefore any recolonisation of the river Liza is likely to involve dispersal of juveniles from the Ehen population. Distance from scout camp footbridge to the mouth of the river Liza 3.7km
  • The River Ehen from its outfall at the Lake to its confluence with the River Keekleis a Special Area of Conservation (SAC). The River Ehen is also a Site of Special Scientific Interest (SSSI), it holds the largest population of fresh water pearl mussel in England and this is the primary reason for it qualifying as a SAC.

A formal assessment of SSSI condition was carried out during 2012 following the low-flow incident resulting in high levels of stress and mortality in the mussel population. This assessment considered that the River Ehen was in unfavourable declining condition. The assessment was made largely on the basis of the declining condition of the freshwater mussel population as the primary interest feature of the river SSSI/SAC, reflecting the issues relating to abstraction, compensation flows and diffuse sources of pollution (siltation and nutrients) but in particular the lack of juvenile recruitment sufficient to sustain the population. (Natural England)