Mistnetting guidelines : Checklist, Do’s and Don’ts

Author:: Ashwin Warudkar, Chiti Arvind, Naman Goyal, Robin VV, Vinay K L.
Copyright:: None
Date:: 09/10/2022

Purpose

Guidelines for field sampling and mistnetting.

A) Preparation of Kit

A Mist-netting kit (including blood sampling) involves the following items

Mist nets of different lengths: The most commonly used nets in our lab are 12m long net, while in some cases, having a few 6m long nets also helps target capture of some species. Mist nets should be carried in polythene bags. One bag per net.
Poles: EcoTone’s telescopic carbon fibre poles are used. We also have some metal poles. Two poles per net should be calculated
Ropes: Jute ropes are generally used. Two ropes per net should be calculated.
Mist-net Repair Kit: This kit should be carried in case there is a need to repair the net damage. The repair kit can remain at the field station.
Bird Bags: Cloth bags with cotton strings to tie them must always be there in the mist-netting kit. The bags should be large enough to hold medium-sized (crow minus) birds. Around 10-20 bags should be carried with each team. The bags should be dry and clean.
Bird Banding Manual: Make sure to have read the two manuals <Links here> before the field deployment.
Tool Box: A proper toolbox should store all the blood sampling and measuring ringing equipment. The items below should be included in the toolbox.
Rings: Aluminium rings made by [BNHS or] INRING of the minimum sizes: Z, A, AB, B, C should be available. Colour rings along with their applicator can be carried if required. In the case of colour rings a separate sheet containing all the possible combinations to be carried.
Ringing Plier: Ringing pliers (Avinet /Porzana) should be carried. The plier should have the facility to apply rings up to size C. The pliers should be clean, smooth and not rusted.
Ring opener: Ring openers should also be carried. This is to open the supplied rings and apply on the birds.
Gridded board for photograph background: Green or black coloured cutting mat of the size A4 and A3 work best. If not available, 1sq.cm. grided sheet downloaded from the internet can be printed and laminated for the same purpose.
Vernier Calliper: A Digital vernier calliper (preferably of plastic) is suitable for the measurement of tarsi and beak. We stopped using Mitutoyo due to the sharp tips of the callipers.
Wing Ruler: A wing scale or wing ruler made of stainless steel should be carried. Wing rule should have measurement markings from both ends and a bent notch at one end.
Pesola Spring Balance: Pesola spring balances of 30g, 100g, 300g and 600g should ideally be carried in their plastic cases. Digital weighing balance can also be used instead.
Bird weighing cone: Plastic cones of two different sizes (small: of the size of flycatcher +/- and large: of the size of babbler +/-) should be available. The cones should be intact - not torn or damaged.
Permanent markers to label vials
Needles: Needles (of the size 24) to prick the skin of the birds should be carried. The needles should be bought from a proper surgical shop and should be sterile.
Syringes: At least 10 Syringes of 5ml or 10ml volume, along with a needle attached, should be carried. This is to expel coagulated blood from the capillaries into the collection vials.
Cotton Buds: A box of at least 100 cotton buds should be carried. This is to clear the area to prick the bird, and also to apply antiseptic fluid and pressure post sample collection
Cotton ball
Capillary tubes: BTCT (Bleeding Time Clotting Time) capillary tubes must be used. The tubes ideally should come in a cylindrical plastic container with a hole on the lid. Use non-heparinized tubes (Heparin can interfere in PCR and other downstream processes).
Blood Storage Solvent: Queen’s lysis buffer or ethanol-filled vials of 2ml size should be carried in 96 section box.
Antiseptic fluid bottle. A diluted aliquot of Savon in water should be kept in an eppendorf for easy use.
Label Stickers: Paper stickers with good adhesive should be carried.
Parafilm roll: Can be obtained from the lab at Tirupati. Should be used to seal the caps of the vials after filling them with the blood sample.
FTA cards if required to take blood samples
Scissors
Empty plastic bottle as a trash can for used needles and cotton buds and capillary tubes.
CAT Phone: Fully charged android phone, preferably CAT phone (with ODK app installed and appropriate forms imported), should be carried : This may be obsolete now, better to use personal phone with updated ODK.
Printed Datasheets: A few, just in case the phone doesn’t work
Foldable table and chairs for processing the bird
Head Torch: In case of early dawn or late dusk.
Extra Vials and storage solvent
A bag pack to carry the toolbox etc.
Sanitizer bottle
Speaker for playback. Excessive playback especially in the breeding season should be avoided.

B) Checking nets and poles

The mist nets should be checked thoroughly for any damage before packing for the field. All the damaged nets should be separated out and marked for repair later. Mist nets should ideally be carried in polythene bags with their end holders tied together with the white loop secured around the other black loops. Please remove any debris that may be stuck in the nets. This is to avoid the entanglement of the net while deploying. All the poles to be carried should be checked for any damage.

C) Site Selection

Selecting an appropriate site to trap the target species is crucial in order to maximize the efficiency given the time constraints of our sampling. For trapping understorey bird species, a mist net should have understory vegetation fairly thick on both sides of the net. A small survey of the plot on a previous day may help to locate the sites with regular bird movement between bushes. Vegetation should not be too close to the net hence a small amount of vegetation thinning may be required. Please note that cutting should not be too much to create a disturbance that birds would notice and impact their activity. Best sites are like trails/paths where minimal vegetation modifications have to be made. If small branches are protruding into the net area, best to use a rope to pull them back rather than chop them. Vegetation with flowering or fruiting plants would ensure more captures. Ideally, the site should be selected and prepared on the previous evening, and nets should be placed on the same evening. If much clearing is required - e.g. in areas with high weed infestation, it maybe good to clear the net sites a few days before starting a deployment. This ensures less disturbance to the birds and assures more captures when the nets are opened.

D) Setting up Mist-nets

Following the previous point, mist-nets should ideally be placed on the previous evening of the session. The mist-nets have 5 pockets which are marked by 5 loops on either side. The white-coloured loop generally marks one end and should be kept at the top or below. Twisting of the net often happen and should be resolved before placing the loops on the poles. The ropes should be tied with a simple knot with an acute angle pointing in the direction of the net placement. A snare like knot is generally helpful. The researcher should ensure that the net is tightly stretched at all the pockets but not too tight. Most field assistants are well-trained in placing the nets, yet supervision by the researcher is necessary. After placing the nets, the nets should be closed, and the hanging loops should be rolled over. It is the responsibility of the lead researcher to check each net to ensure that all the nets are closed before leaving the site that evening.

E) Opening and monitoring nets

Nets should be opened at the crack of dawn, just before the start of the birds’ activity (marked by the dawn chorus). Forked sticks can be used to stretch the top loops. The nets should be visited ideally every 15-20 min. The researcher should check all the pockets properly as sometimes smaller birds trapped in the lowermost pocket go unnoticed. The nets should not be visited too frequently (<5 min or so); otherwise, birds in the vicinity get disturbed, and the capture rate goes down. On the other hand, keeping too long intervals can impact the trapped birds as predators tend to attack the net. An alarm of every 15 or 20 minutes on the phone would be best. The researchers should ensure that the field assistants check all the nets regularly. Playbacks can be used for target capture. However, playback should not be done continuously for more than 5 min, and the volume should be maintained to be at a natural bird’s sound. The most important is to keep the count of active nets every time.

F) Removing the trapped bird from the net

When a bird is trapped, the researcher should approach the net very carefully and calmly. Rushing towards the net may startle the trapped birds making it struggle more and get poorly entangled. The researcher should first determine the side from which the bird is trapped in the net pocket. This is most easily determined by looking at the side from which the bare belly is seen. The wings and legs are most commonly entangled in the net. The net can be removed layer by layer, slowly. The researcher can go from the belly and first free the legs and hold them so that the bird can be manoeuvred if needed. Net threads go around the shoulder when the wing is stuck. The thread can be located by opening the wing carefully and can be removed over the shoulder slowly. Sometimes, the net thread gets entangled in the tongue notch of the bird. In this case, the beak has to be opened slowly and the thread can be pushed inside first to remove from the notch and then removed out. The lead researcher should always monitor the new interns and may have to interfere if the entanglement is very complicated. Again, the field assistants are generally well-trained in removing the bird from the net, but they should be regularly monitored and make sure that they don’t take things lightly. The bird, once removed from the net should be immediately put into the bird bag. The researcher should always carry 3-4 bird bags while visiting the net. Carrying a bird in hand toward the processing station should be avoided. If multiple birds are captured at a time, the bird bags should be hung at around 1m height to a substrate (a long stick or something) from where it must not fall down when the bird moves inside.