What does it do?
The bird4pop model simulates the lives of nidicolous passerines (perching birds who bring food to their young in the nest).
It simulates their central-place foraging around their nests during the breeding season, chick production, dispersal and survival of adult and juvenile birds.
This enables the model to predict the relative abundance of birds across a landscape
Where does it come from?
The bird4pop model was co-created by researchers working at the UK Centre for Ecology & Hydrology and researchers working at the British Trust for Ornithology.
Bird4pop model development is led by Emma Gardner.
How does it work?
Bird4pop reads in a landcover map plus additional maps giving the locations of fine-scale habitat features (e.g. hedgerows, field margins).
It combines these with expert opinion estimates of the amount of nesting and breeding season foraging resources each landcover type is expected to offer the birds that are being modelled. This allows the model to map the nesting resources and map the breeding season foraging resources provided by the landscape.
It then places virtual nest sites in the landscape, putting more in places where there are more nesting resources, and initially places one pair of breeding birds at each nest site.
The model uses information on how far birds typically fly away from their nests, when foraging during the breeding season, to work out the amount of foraging resources the birds would be able to gather. It assumes that birds spend more time foraging in nearby places and places with more foraging resources.
The model calculates how many chicks fledge from each nest, assuming that breeding pairs who gather more food produce more chicks.
Separate survival probabilities for adults and juveniles are then used to calculate the number of adult and juvenile birds that survive the winter.
Surviving birds are dispersed across the landscape and paired up at available nest sites, assuming that dispersed birds preferentially choose nest sites that are nearby and in areas with more nesting resources. If there are more pairs than there are nest sites available then these extra birds are lost from the landscape.
The model loops round and round multiple generations to work out where the birds would be able to survive, given the composition and configuration of habitat resources provided by the input landscape.
What knowledge does the model use?
The bird4pop model is parameterised for woodland specialist birds, woodland generalist birds, edge-nesting farmland birds and skylark (an open-nesting farmland bird).
It uses:
- expert opinion on these birds’ habitat preferences from a survey of 4 experts in bird ecology
- literature data on breeding densities, clutch sizes, movement ranges and survival probabilities
How do we know it works correctly?
We compared bird4pop model predictions to observed bird abundances recorded at 4874 sites across Great Britain by volunteer surveys taking part in the BTO/JNCC/RSPB Breeding Bird Survey.
How has bird4pop been used?
We have used bird4pop to explore with local communities how past land use changes have affected different groups of birds.
We’ve also used bird4pop to explore how future land use changes might affect birds over time, working with Defra’s national evidence teams.
Visit our pages on supporting decision-making to find out more about this work.
*4pop models 