1. BB30156 Conservation Biology
Tools: Monitoring and population estimation

2. What is monitoring?
‘To watch, to keep track of, or check for a specified purpose’
Count individuals/ species richness/ diversity over time to detect change
Series of standardised surveys

3. Why monitor?
Monitoring is needed to assess the effectiveness of conservation measures and to provide early warning of problems
Results of monitoring should be fed into regional, national and global conservation targets
E.g Biodiversity Target of Convention on Biological Diversity (CBD)

4. Conservation needs monitoring
Detect a problem
Research
What is the solution?
What is the cause?
Action
Test solution
Implement solution
Did the management work?
Carry on monitoring…

5. Conservation needs monitoring
Abundance and distribution are fundamental
Conservation of endangered species
Management of pest species
Managing harvested populations

6. Conservation needs monitoring
Detection of trends in all populations is important
If declining fast, can intervene before population becomes too small
Science or evidence based wildlife conservation and management

7. Different types of monitoring
‘Scientific monitoring’ by professionals
‘Participatory monitoring’ by local ‘stakeholders’

8. Participatory ecological monitoring in Madagascar
Biodiversity
Locally endemic, rare, endangered species
Species targeted for hunting
Pressures
Deforestation
Burning
Cut stumps
Ox-cart tracks/paths
Lemur traps etc.
Number of giant jumping rat burrows, Number of narrow striped mongooses, number of groups and of individuals of diurnal lemurs (targeted for hunting), number of white breasted mesites, giant couas etc., number of tortoises, chameleons etc., Hazomalany,
Scoring system very flexible.
Narrow striped mongoose
Giant Jumping rat
Berthe’s mouse lemur
Flat tailed tortoise

9. Pressure-state-response monitoring
Organisation for Economic Co-operation and Development (OECD, 1993)

10. Pressure-state-response monitoring

11. BirdLife International’s monitoring strategy
Update of IUCN Red List status (all bird species) and actions (Globally Threatened Birds)
Simple monitoring of Pressure, State and Response (including safeguard status) at all IBAs in network countries, supplemented by remote sensing (within and outside the network)
Population trend assessment for all Critically Endangered species, using a ‘species guardian’ approach
Assessment of trends in relative abundance of a set of common bird species using birders’ day lists (see
Regular update from network NGOs on membership, number and membership of affiliated Site Support Groups (SSGs), and self-evaluation against criteria of sustainability and stability

12. Examples of monitoring programmes

13. Successful monitoring programme
BTO Common Bird Census
Huge number of volunteers utilised to cover UK
Powerful monitoring programme
Informs intensive research and conservation action

14. Counting animals and plants is easy….

15. ….or is it? Rare or elusive species Low density populations
Dense and remote habitat
Difficult field conditions
Confounding factors

16. Survey techniques Different survey techniques Total counts
Index of abundance
Plot sampling
Distance sampling
Mark-recapture
Choice of technique depends on many scientific, biological and logistic factors

17. Total counts Very small populations Can ID individual animals
Territory mapping of song birds
Highly aggregated populations
Colonial nesting birds
Seals on a beach

18. Can we count all the animals in the population with certainty?
No, It is usually impossible!
Animals move, hide, look the same, inactive, too numerous, dense habitat
Census is a total count e.g. very small populations or seals on a beach during breeding
If you can’t do a total count then need to sample the population = survey

19. What is sampling? A way of collecting observations
Arbitrary or natural
Random or systematic = representative
Independent
Replicated - more samples are better than a few
Extrapolate results to estimate total population size

20. Precision vs accuracy Accuracy = reliability
‘Bias’ is difference between estimate and true mean
Precision = repeatability
A precise estimate has low sample variance
Aim to remove/minimise bias in survey design and thus our estimate

21. Considerations for sampling design
Define the research question before you start
Distribution and approximate density
Density contours e.g. altitude, habitat gradient
Level of precision required
Resources available
Definition of survey area and sample units
Sampling must be representative

22. Index of abundance Frequency of animals or sign per unit effort
‘Relative’ abundance
Low density and elusive animals
Animals difficult to catch or mark or recapture
In dense habitat and remote areas
If have few resources

23. Index of abundance Mist netting – bats, birds
Surveys of sign - elusive and nocturnal animals
Playback calls e.g. territorial birds and mammals
Pit fall traps – reptiles, amphibians, invertebrates
Camera-trapping – e.g. nocturnal mammals

24. Relationship between population size and index of abundance
100 50 10 5
Introduce ideas of research questions and monitoring programme objectives – but will talk later in more detail

25. Plot sampling Quadrats, strips, circles
Assumption – can accurately count all animals in plot
D = N/A
Estimate of absolute abundance, i.e. population size

26. Plot sampling High density and clustered populations Sessile animals
Invertebrates
Small ground living reptiles
Plants
Sign e.g. dens, burrows, nests

27. Can we always detect all the animals in a plot with certainty?
Use statistical methods to estimate probability of detection or capture

28. Distance sampling
Assumes probability of detection declines with increasing distance
Use a number of line or point transects to sample a population
Estimate detection probability by measuring distances

29. Distance sampling Plot distances on a histogram
Number of animals detected declines with increasing distance
Probability of detecting animals declines with increasing distance

30. Detection probability
Assume all animals on the line are recorded
At 0m you have a probability of detection, p, of 1
Use p, or the detection function, to calculate the proportion of animals that are detected

31. Estimating abundance from a distance sampling survey
number of observations
% area sampled x detection probability
N =

32. Distance sampling Need to meet assumptions Marine mammals
Primates, ungulates, whales
Birds
Reptiles, amphibians
Fish
Sign e.g. burrows, nests, dung

33. Mark-recapture
Mark-recapture allows you to estimate the probability of capturing animals
Uses the proportion of marked animals that are recaptured after release
Can estimate absolute abundance
Useful for animals that are trappable but are not readily detectable even close to the observer
Useful when information on other population parameters is needed

34. Mark-recapture N = n x M m Where, N = abundance
M = number of individuals caught in 1st sample, marked then released
n = number caught in 2nd sample
m = number of marked individuals in 2nd sample

35. Mark-recapture Usually requires high recapture rates
Requires large amounts of effort
High density populations
Small mammals
Reptiles
Amphibians
Fish

36. Mark-recapture Other methods of capturing individuals
E.g. by hand, DNA profiling, camera-trap, individual recognition
Large mammals e.g. bears, tigers, whales
Even lions on tourist photos!
Number of assumptions that are hard to meet so abundance estimation can be difficult

37. What is a trend? Changes in population size over time
Population dynamics of species vary widely
Driven by births, deaths and movement
Complex processes
Short term fluctuations occur in long terms trends

38. Analysing trends Graphs
Express as % change over time e.g. 50% decline over 10 years
Linear regression analysis of abundance
Complex process models e.g. GAMs
Early warning system

39. What size of trend can you detect?
How able is a monitoring programme to detect a trend of a certain size over a certain time interval?
Depends on natural variability of population in time and space, sample sizes, survey design
Best to estimate at design stage
Power analysis
E.g. a monitoring programme has 80% power of detecting a 30% change over 10 years

40. Summary
Monitoring is vital tool in conservation and natural resource management
Pressure, state and response framework
Early warning system and evaluate effectiveness of conservation action and progress to targets
Identification of factors of decline
Variation in detection probability can confound monitoring data
Effective management of programme and long term funding is key
Combination of scientific and stakeholder participatory monitoring

41. Further reading ‘Ecological methodology’ Krebs CJ
‘Ecological census techniques’ Sutherland WJ
‘Bird census techniques’ Bibby et al
‘Sampling Rare or Elusive Species : Concepts, Designs, and Techniques for Estimating Population Parameters’ Thompson WL
‘Introduction to Distance sampling’ Buckland et al (2001)
Monitoring matters: examining the potential of locally-based approaches. Special Issue: Biodiversity and Conservation, 14, No. 11, Oct 05