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Urban Nesting Gull Survey


Seabirds Count: Urban Nesting Gull Surveys

Seabirds Count: Britain and Ireland’s 4th Breeding Seabird Census

Survey Timings – 23rd April – 7th May

Since 1969 there have been periodic censuses of breeding seabirds in Britain and Ireland. The last census was completed in 2002; due to the time that has passed, it is important another survey takes place. Seabirds Count was developed by the Seabird Monitoring Programme (SMP) partnership and is being coordinated by the Joint Nature Conservation Committee (JNCC). Its goal is to gather vital data on the breeding numbers of seabirds, with the aim of understanding how distributions and populations have changed. Survey work started in 2015 and aims to be completed by the end of the 2020 breeding season.

As part of the Seabirds Count census, volunteers across the whole of the UK will be participating in surveys of breeding seabirds during the spring/summer months of 2019 and 2020. During these seasons (late March – mid June) there will be surveys of urban nesting gulls, taking place in many of our towns and cities. These urban surveys will play a vital role in understanding how the UK population of both Herring and Lesser Black-backed gulls are faring. Herring gull numbers in natural breeding sites such as cliffs, rocky coasts and moorland declined by a 3rd between 1986 and 2015. By conducting surveys of urban nesting gulls, we can understand whether these declines at natural sites are a product of these birds moving into urban areas, or if the declines are more widespread.

Volunteers will mainly be using two types of survey method, one will be surveying roof tops from a vantage point, the other will be from the ground. These surveys will only happen once at each site, unless the surveyor perceives there to be an issue with the initial count.

Urban Gulls: Survey methods

Given the expansion in the distribution of urban nesting gulls over the last 15-20 years, an alternative method of estimating the UK breeding population is necessary. This is what the second part of the surveys aims to do. This new method will consist of surveying a sample of 1km squares in urban areas, within each SMP administrative area. The sample will be a stratified random sample, based on the number urban squares, and the ratio of strata1, found within each administrative area. With such sampling there is a chance that some urban squares will not contain gulls, however, for the data to be statistically robust and not bias, these squares will still need to be surveyed and reported on. This survey will be using correction factors produced through a parallel project, being undertaken by the BTO under a contract from DEFRA, to calculate population estimates for the UK’ urban nesting gulls.

Square Survey Method

For the sample survey will be counts of herring and lesser black-backed gulls from ground-based surveys. Counts of lesser black-backed gulls and herring gulls will need to be reported on separately, for each 1km square. A count for all three units below will need to be recorded for each species:

AON = apparently occupied nest (well-constructed nest or scrape nest, either containing eggs or young, or capable of holding eggs (possibly attended by an adult) or an apparently incubating adult),AOT = apparently occupied territory (estimated by the spacing of birds or pairs on different rooftops and observations of apparent territorial behaviour, when actual nests cannot be discerned. Any AONs should also be considered a territory, so the number of AOTs will always be equal to or greater than the number of AONs.)IND = Individual adults (Count the total number of birds in full adult plumage. Individual birds should only be counted once. However, where movement occurs it will sometimes be impossible to be certain whether some birds have already been counted in which case you should use your best judgement to decide. Birds in flight can be counted if it is clear that they are using rooftops in the square, but birds observed flying over the square should not be counted)

Also needing to be recorded:

The survey square, date of survey, time of survey and weather. These should be noted on the count sheets in the appropriate box.A note of any use of gull deterrents or control measures e.g. netting on roofs will be much appreciated.A rough estimate of the % of the square that could not be accessed for survey (i.e. private land)Finally, in the comments section note how many of the gulls counted were thought to be away from breeding territories (i.e. flocks of gulls resting on lakes or foraging on a playing field).

If you sign up to survey a square, a link to an online map will be provided to you by your regional coordinator, this link works best on a mobile device. If you wish to print off your survey area this link: will be more useful. All you need to do is enter the grid reference of the square you are surveying.

Survey Timings – 23rd April – 7th May

I need all the help that I can get, I have 80 random 1 km squares to try and cover so I would appreciate your help with this survey.  Please contact Mick Wright at

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