WALLACE RESOURCE LIBRARYWALLACE RESOURCE LIBRARYModule 02 – Survey Techniques:Module 02 – Survey Techniques:

D03 – Comparison of bird survey techniquesD03 – Comparison of bird survey techniques

WALLACE RESOURCE LIBRARYWALLACE RESOURCE LIBRARYModule 02 – Survey Techniques:Module 02 – Survey Techniques:

D03 – Comparison of bird survey techniquesD03 – Comparison of bird survey techniques

Why Survey Biodiversity?Why Survey Biodiversity?

• Global decline in biodiversity

• But how do we know?

• In order to assess biodiversity we must apply appropriate survey techniques

• This provides the information we need to understand what is happening to biodiversity on a local as well as a global scale

Why Survey Biodiversity?Why Survey Biodiversity?

• IUNC Red list of Threatened SpeciesExtinct (EX)Extinct in the Wild (EW)Critically Endangered (CR)Endangered (EN)Vulnerable (VU)Near Threatened (NT)Least Concern (LC)

How do we Survey Biodiversity?How do we Survey Biodiversity?

• Global or National scale - Satellite images• Local scale - Capture-Mark-Recapture- Transect and Distance sampling- Passive trapping- Camera trapping- Direct counts e.g. Helicopter surveys

Why are birds important?Why are birds important?

• Birds often used for as indicators of ecosystem health :

– Taxonomically well known– Abundant and apparent– Large samples easy to obtain in order to look at variation– Predictable, rapid and linear response to disturbance that

can be analysed– Bird abundance and diversity closely associated with other

species and ecosystem resources– Relatively unaffected by seasonal variations

Point countsPoint counts• Suits dense habitat such as forest and scrub

• All birds available for sampling, including more cryptic, shy species

• Suits species-rich habitats such as tropical forest

• Time is lost moving between points, but counts give time to spot and identify shy birds

• Double counting birds is a concern within the counting period

• Birds may be attracted to the presence of observers at counting stations

Mist nettingMist netting

• Only surveys birds that occupy the lower canopy

• Additional data can be collected (e.g. weight, sex)

• Ideal when dealing with birds that are hard to identify from sight or vocalizations

• Suitable for all terrestrial habitat types

• Requires trained bird handlers

MethodsMethods

• Survey took place in Cusuco National Park, Honduras

• Surveying to help manage and conserve forests in Honduras for bird species

• Need to discover which species occur in the forest

• 70 hours spent on point count surveys

• 400 hours completing mist netting surveys

Research questions:Research questions:• Which of the two methods (mist nets or point counts) do you think is the most efficient for surveying

birds in Mesoamerican cloud forest?

• Comparing the methods:– At any particular point, which method detected the most species? – Do the two methods detect the same kinds of birds? – Can you give examples of the kinds of birds which mist-nets are better at surveying than point counts,

and vice versa?

• Recommendations:– Which survey technique should be the main methodology for the planned large-scale survey of

Honduras’s cloud forest?– If the time is available, would you recommend the other method as an important secondary

technique? If so, why?

Summary and conclusionsSummary and conclusions

• Point counts more efficient

• Mist nets only survey understorey birds

• Point counts primary method

• Mist netting secondary method