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BB30156 Conservation Biology Tools: Monitoring and population estimation.

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Presentation on theme: "BB30156 Conservation Biology Tools: Monitoring and population estimation."— Presentation transcript:

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 Monitor Detect a problem Research What is the solution? What is the cause? Action Test solution Implement solution Did the management work? Monitor 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. Giant Jumping rat Berthes mouse lemurFlat tailed tortoise Narrow striped mongoose

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

10 Pressure-state-response monitoring

11 BirdLife Internationals monitoring strategy 1.Update of IUCN Red List status (all bird species) and actions (Globally Threatened Birds) 2.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) 3.Population trend assessment for all Critically Endangered species, using a species guardian approach 4.Assessment of trends in relative abundance of a set of common bird species using birders day lists (see 5.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 cant 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 Population size Index of abundance Relationship between population size and index of abundance

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 1 st sample, marked then released n = number caught in 2 nd sample m = number of marked individuals in 2 nd 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

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