Bird Monitoring Report 18-19

Bird Monitoring Report 18-19

The Bird Monitoring Report 18-19 is the first report on bird population and distribution at Walthamstow Wetlands written by London Wildlife Trust. It is the fourth annual report of five, the final report is due early summer 2020.

The Bird Monitoring Programme was established by BSG Ecology as part of the planning application and Habitat Regulations Assessment as a requirement to monitor bird distribution and disturbance in response to increased public access. The Walthamstow Wetlands Partnership are tasked with monitoring the effect on ‘key species’ attributed to the SSSI and SPA for a five-year period.

gadwall at Walthamstow Wetlands


Using the previous surveys completed by BSG Ecology, London Wildlife Trust have compared the population and distribution of bird species, and the disturbance caused to those species using a series of maps and numerical data.

There are several key findings from this year’s report;

  1. There are no significant changes of immediate concern or warrant the need for intervention
  2. There were variations in populations of key species during certain periods. Both high and low figures are broadly similar to previous years of survey
  3. The distribution of waterfowl is showing a visible bias towards reservoir islands away from banks and open pathways. However, this change in distribution is likely to be multi-faceted rather than as a direct impact of increased visitor access.
  4. 66% of disturbance events occurred on closed pathways
  5. The remaining 34% of events occurred on open pathways. Only a third of these affected designated species and the majority of these events were recorded as low-level.
  6. However, there are several areas where disturbance was concentrated and therefore would benefit from habitat enchantments or natural screening.

Pochard at Walthamstow Wetlands


Tufted duck at Walthamstow Wetlands

Tufted Duck

While there is nothing of immediate concern in the results for the 2018-19 survey period, London Wildlife Trust will continue to monitor in the same manner for 2019-20.

The Walthamstow Wetlands Partnership are keen to keep disturbance to the best possible minimum and there are several factors not mentioned in the report to support this aim. The opening hours, habitat gate plans, restrictions on pets, no swimming and designated cycle/jogging routes ensure that areas used and required by waterfowl are protected from potential high levels of disturbance that could affect population and distribution.

For a brief explanation of the methodologies and maps please continue reading.

Shoveler at Walthamstow Wetlands


Designations and designated species

There are six key species that contribute to the designations of the site. However, this report mainly focuses on the four key duck species and their respective seasonal population and distribution;

  1. Breeding Season – tufted duck, gadwall, shoveler & pochard
  2. Post breeding (moulting) – tufted duck
  3. Over wintering – tufted duck, gadwall, shoveler & pochard

There is a brief summary of the Heronry survey and census which follows BTO methodology.

Coppermill Stream at Walthamstow Wetlands

Coppermill Stream


Every two weeks London Wildlife Trust ecology volunteers survey all ten reservoirs identifying, counting and recording species of waterfowl and their location on site to produce three key data points; bird species, numbers of individuals and location. This is known within the team as a Full Count.

For every second Full Count a Disturbance survey also takes place. Disturbance surveyors record waterfowl level of response to the occurrence of a human stimuli, i.e. walkers, joggers, cyclists and vehicles. Levels of response are based on how far and how quickly a bird moves away from the stimuli. For example, a score of 1 is given to a tufted duck that moves slowly away but quickly returns to its former position and a 9 is given if the grey heron flies away and appears to leave the site altogether.

The data from these surveys is analysed numerically, by looking at ‘peak counts’ (highest number of birds of a single species in any given time) and by way of comparison to heat maps past and present.


To represent the data collected ‘heat maps’ (geographical representation of the data) have been created that illustrate the population and distribution of a given species during a given period.

Each of the ten reservoirs have been assigned a letter from A-I and divided into 50x50m squares, and assigned a numerical value, to create a unique ‘grid code’ i.e. G34 or I12. This allows surveyors to record birds’ location in the reservoir using the Grid Code system.  

Grid map at Walthamstow Wetlands

Grip Map

Once a years’ worth of data has been collected heat maps are created. Colour gradients are used to illustrate the quantity of a given bird species using squares of the reservoirs ‘Grid Code’ system. Light colours illustrate low numbers and dark colours higher numbers, and their relative value is shown in the maps key.

In total ten result maps have been produced. One for each of the designated duck species during the over-wintering and breeding seasons, one for tufted duck during the summer moult and one disturbance map.

If you have any questions relating to the Bird Monitoring Report at Walthamstow Wetlands, please contact the Ecology Ranger Charlie Owens, To view full report, please click here.

Results map at Walthamstow Wetlands

Results Map