Nocturnal Bird Count Protocol in the Western Ghats

Nocturnal Bird Count Protocol in the Western Ghats

This scientific protocol is designed for state forest departments to standardise nocturnal bird monitoring, focusing on owls and frogmouths, while minimising disturbance. The protocol assumes support from the forest department for conducting studies in the night as well as for minimal playback of calls required for a scientific study of nocturnal birds. While this is designed specifically for the Western Ghats, it would work with minor adaptations in any forest areas in Peninsular India.

Study Area

• Location: Any Wildlife Sanctuary or Reserve Forest and surroundings under the jurisdiction of a Forest Department.
• Habitat: Typically any mix of wooded habitats including some open areas.

Transect Design

• **Number of Transects:** 5 transects* (One team in each transect; each team should have three observers and at least one forest guard.)
  • One Checklister (Good Ear-birder), One Playback-person, One Merlin Recorder, One Guard
• **Length of Each Transect:** 2 km*
• **Point Count Interval:** Every 250 m along each transect.
  • Note, in some places, the transect will be a winding road; it is preferable to drop some intermediate points so that the 250m distance does not become 150m or 100m, defeating the purpose of keeping points non-overlapping.
• **Total Point Counts:** 7-9 points per transect, 40 points in total across all transects.

*The actual number of transects, the distance of each transect, and hence the total number of point counts  may vary depending on site conditions, local logistics and available resources.

Field Schedule

• Survey Days: 2 consecutive nights.
• Timing: Start ~30 minutes after sunset; each transect (~2 km) takes ~4.0 hours to complete (21 minutes per point, 7-9 points, total walking time of 30 + 30 min).
• Moon Phase: Conduct during similar moon phases to standardise light conditions for the repeat survey next year.

Playback Setup and Calibration

1. Playback Device:

• Use identical models of mobile phones or devices with similar output quality.
• Mobile phones are preferred due to availability and standardisation.
• Bluetooth speakers should be avoided unless explicitly permitted and carefully calibrated. 
• Ensure playback devices are calibrated before the survey to produce consistent volume levels.
• Volume calibration: Play test recordings in the field to achieve clear audibility (but not excessive loudness) at ~50 m.

2. Playback Files:

• Small Owl and Frogmouth Playback: Includes calls of six species (e.g., Jungle Owlet, Sri Lanka Frogmouth, etc.).
• Large Owl Playback: Includes calls of six species (e.g., Brown Fish Owl, Spot-bellied Eagle Owl, etc.).
• Use only a single vocalisation of every species, and that be the most likely one to get a response.
• Pause briefly (at least 10* seconds) between calls of different species. Each playback should be exactly of the same duration, say 1* minute long.
• No nightjar calls need to be included in the playback files as they are less likely to respond to playback.
• All teams will use the same pre-prepared audio files, playing them in the same sequence and duration at every point.

3. Prototyping:

• It is highly desirable for a small team to visit the field site the previous week to decide which nocturnal species are present, how likely they are to respond to call playbacks during that season, calibrate the distances between point count stations, lengths of transects covering the required habitats, and other logistical issues.
• Excluding species that are rare or that rarely respond to playback from the playback sequence will add to the efficiency of the survey.

4. Training & Field Preparation:

• Create an archive of all possible nocturnal calls in the area (including other nocturnal ones like Slaty-legged Crake, Flying Squirrel, Loris, etc.) and play repeatedly to volunteers during evenings for training. Volunteer training is very important. 

Survey Protocol at Each Point Count

1. Arrival: Arrive quietly at the point. Allow one minute to settle and avoid unnecessary movement or noise. Keep the lights off.

2. First Observation Period (Five minutes):

1. Conduct a silent point count for all nocturnal bird calls.
2. Record all birds heard or seen into a complete eBird checklist, and entry in the checklist, by default, means call head.
3. Open Merlin simultaneously and record the sound.
4. Add visual records (if any) in the comments for that species.
5. Use the direction of calls to estimate and record the number of vocalising individuals.
6. Always keep the mobile brightness at the lowest possible.
7. Stop the checklist after five minutes. Stop Merlin also after five minutes. Even zero species checklists can be submitted.

3. Second Observation Period (Five minutes):

1. Play the small owl and frogmouth playback file.
2. Start a new eBird checklist at the start of the playback to record immediate responses. Keep a new Merlin recording as well.
3. Record all responses (vocal or visual) in the checklist.
4. Note the vigour of responses in comments (e.g., close approach, repeated calls). Use short codes in the checklist to avoid brightening the mobile for too long.
5. Stop the checklist after 5 minutes.

4. Third Observation Period (Five minutes):

1. Play the large owl playback file.
2. Start a new eBird checklist at the start of the playback to record immediate responses. Keep a new Merlin recording as well.
3. Continue the eBird checklist process as previous.
4. Stop the checklist after five minutes.

5. Fourth Observation Period (Five minutes):

1. Same as the first observation period—silent listing.

6. Move to the Next Point:

1. Walk silently to the next point.
2. Based on how many species are being targeted, the number of playback-based observation periods could be increased or decreased. E.g., if the target is only 2 species, then only one playback-based observation period is sufficient.

Precautions and Safety

Elephant and Wild Animal Activity:

1. Volunteers should stay alert for signs of wild elephants (e.g., fresh dung, footprints, broken vegetation).
2. If signs of elephant activity are detected, immediately return back to safety.
3. Stick to regular pathways or wide walking paths. Avoid entering dense thickets and forests.

Equipment:

1. Use a minimal flashlight to avoid disturbing wildlife and birds. Seeing birds is not essential at all for the survey; presence/absence of calls suffices. No photography is expected.
2. Wear good shoes and carry protective clothing suitable for nighttime fieldwork.
3. Get approval from the concerned forest official who shall facilitate the conduct of the protocol by providing adequate guard-support to walk in forests, approvals for restrained playback in forests as specified in the protocol, and any travel/logistics arrangements.

Data Recording in eBird

1. Complete Checklists:

1. Maintain a complete eBird checklist for every point count station. All are complete checklists, only the playback file is different
2. Checklist 1: Covers the five-minute silent period.
3. Checklist 2: Starts with the playback for small owls. 
4. Checklist 3: Starts with the playback for larger owls. 
5. Checklist 4: Covers the last five-minute silent period.
6. Add in checklist comments “Silent”, “Small Owl”, “Large Owl” to distinguish between the periods.
7. All checklists to be shared to the group ID <>.

2. Merlin Recordings

1. Transfer all recordings to a google drive. Label the files T1_P2_C3  (Transect 1, Point 2, Checklist 3)

3. Species Details:

1. Record all birds heard or seen.
2. By default, all observations are considered as calls.
3. For visual records, add comments specifying “seen.”

4. Number of Birds:

1. Estimate the number of vocalising individuals using call direction as a cue.

5. Observations outside point counts:

1. Observations while traveling between point count stations can be entered into a single incomplete traveling list for the entire transect. Please note, the observations from the point-count checklists need not be added to this checklist, and “All Species Reported” should be marked as incomplete.

Expected Outcomes

• Comprehensive species lists for nocturnal birds, including relative abundance and responses to playback.
  • For example, we get 160 checklists and 160 recordings, each of five minutes duration. We can annotate the recordings independently of the checklist and compare.

  • Also, we get 80 silent recordings and 80 playback recordings.

• Data on species-wise dependency on playback to detect species.
• Efficacy of simple mobile recordings for nocturnal surveys in the area.
• Baseline data for long-term monitoring of nocturnal bird populations.
• Insights into nocturnal species distribution and habitat use in the area and its surroundings.

Species to Playback (a sample)

This is a sample list of species to playback for a survey in southern Western Ghats. Note, the segregation and order based on the size. 

Small Owls and Frogmouth

Frogmouth, Jungle Owlet, Indian Scops-Owl, Oriental Scops-Owl, Brown Hawk-Owl

Large Owls

Sri Lanka Bay-Owl, Mottled Wood-Owl, Brown Wood-Owl, Brown Fish Owl, Spot-bellied Eagle-Owl

Header Image: Mottled Wood-Owl Strix ocellata © Fareed Mohmed/ Macaulay Library