The winding Sg Mukah.
Nighttime Assessment of Fireflies at Sg Mukah
26th Feb 2010
Observers :
Musa, Anura, Nazeri(MNS MirI) , Hasnaliza, Duffy (SFC Mukah), Tahar Mustafa, Zulkipli Zawawi (boatman).
1 km plank walk in magenta and 8.96 km river track.
Jety/Berth Location: Mukah River Jetty
Side View Pteroptyx Valida. One division of the graph paper is 2mm.
Male light organ indicating P. Valida, apices of the elytra strongly deflexed and the terminal abdominal sternite strongly trilobed or trisinuatetake is typical of Pteroptyx specie. One division of the graph paper is 2mm. Caught at 20:45 N2 53 48.6 E112 07 54.3
Top View of Pteroptyx Valida. One division of the graph paper is 2mm.
We flew to Mukah 25th Feb to take part in the Sarawak Waterbirds Survey covering the Mukah sectors that weekend. We grabbed the opportunity to conduct CFZ for Sg Mukah on the 26th evening.
That Friday after a short walkabout around town, we took a boat across the river to checkout the fireflies amongs't the mangrove alongside the river walking along the plankwalk.
Crossing the Sg Mukah to get to the mangrove plankwalk on the otherside, each crossing costs 0.50cents but boat services ends at 6.30pm. The only way to get back is either by car or charter the same boat.
We walked along the plank towards the estuary and walked back after sunset. The entire area is lined up with matured berembang trees. We were hopeful of seeing fireflies sooner or later as we've been told by locals that they were plenty around after dark. There were several macaques, many mudskippers, Collared Kingfisher and small fries under the plankwalk.
As the dark started to engulf us, we walked slowly back along the plankwalk. We did not see any fireflies all along the walk back to the jetty. One explanation could be the human presence in the area, but we couldn't be sure. Sg Raan in Miri exhibited a healthy population rather close amongst human settlement; the same for Sg Miri near the Lutong segments. Our boatman, Aziz arrived promptly at 8.30pm to take us back across the river to town.
The next day we joined Rose and Daniel for the SWS. Liza from SFC Mukah was very kind to offer us the use of her car for the survey after our own rental car failed to appear at the promised time. We traversed the beaches along the coast but broke off early from the team to get some rest and prepare for our CFZ, planned to start 6.30pm the same day.
At the jetty, we were joined by Liza and Duffy from SFC Mukah office.
At 6:30 we started our survey slowly just to wait for the dark. We stopped at an area where the egret roosted. More than 500 mixed flock of egrets consisting of Cattle Egret, Intermidiate Egret, Little Egret and Great Egret. We saw them again on our return trip from the CFZ, it was too dark to get an approximate figure perhaps well beyond 500 egrets by then.
We started our survey by taking reading for water, air temperature, salinity and pH. We then slowly ride upriver. The early parts of the river is lit by all sorts of structures : from human habitation, swiftlets house, factories and quays. These are spotlighted and at some places were so bright that it's nearly impossible to see anything. Finally at 7:15pm, we noted one firefly.
Subsequenly we saw more trees having fireflies. The fireflies were displaying very high in the trees. Observations were made difficult by presence of bright starry skyline as well as some human habitation just beyond the trees. Light pollution from nearby structures in some areas didn't help our predicament.
With difficulty we managed to capture 2 male samples. Preliminary assessment tended to suggest that it is of the species Pteroptyx Valida due to the large size. It was only later when at home under a microscope that the samples were confirmed Pteroptyx Valida E. Olivier.
We concluded our survey at 09.50pm.
Field work
START Time: 18:18
Field work FINISH Time: 21:15
PHYSICAL CONDITION:
a. MoonPhase : New moon
80% cloud covered sky.
b. Weather: windy
A digital thermometer reading every minutes and giving an average
readings of the whole trip.
Minimum Average Relative Humidity: 84%
Minimum Average Air temperature 26.6 ° C
Minimum Average water temperature 25.0 ° C
Maximum Average Relative Humidity: 85%
Maximum Average Air temperature 28.9 ° C
Maximum Average water temperature 27.5 ° C
Water pH : 5 at the begining of the trip and 4 at the end of the
trip. Two readings taken at the end to confirm the reading.
Specific gravity: Both reading at the start point and end is 1.000
c. River Condition Current: Slow going down tide, slightly Whitish
sediment river.
Boat used: Mercury 40 hp.
Survey Average Speed 6.0 Km/hr.
Tide: going up
WPT Time Co-ordinate Fauna Fauna Estimated Number
467 18:25 N2 53 46.0 E112 05 54.7 Egrets 1000
468 19:15 N2 54 23.4 E112 06 05.9 Right 5
469 19:19 N2 54 27.0 E112 06 12.6 Right 1
470 19:19 N2 54 26.9 E112 06 13.4 Right 10
472 19:23 N2 54 20.4 E112 06 20.2 Right 1
474 19:31 N2 53 58.0 E112 06 28.2 Left 10
475 19:38 N2 53 39.4 E112 06 45.9 Left 1
476 19:40 N2 53 38.4 E112 06 51.5 Left 4
477 19:40 N2 53 38.7 E112 06 52.1 Left 10
478 19:42 N2 53 41.9 E112 06 54.4 Left 50
479 19:44 N2 53 47.6 E112 06 56.2 Right 100
480 19:45 N2 53 49.9 E112 06 55.7 Right 50
481 19:45 N2 53 51.1 E112 06 55.3 Right 50
482 19:45 N2 53 52.3 E112 06 54.9 Right 50
483 19:46 N2 53 54.9 E112 06 54.4 Right 50
484 19:46 N2 53 55.1 E112 06 54.4 Right 50
485 19:47 N2 53 57.5 E112 06 55.3 Right 50
486 19:48 N2 53 58.3 E112 06 56.1 Right 100
487 19:48 N2 53 58.7 E112 06 56.7 Right 100
488 19:49 N2 53 59.1 E112 06 57.5 Right 50
489 19:49 N2 53 59.3 E112 06 58.3 Right 100
490 19:50 N2 53 59.4 E112 06 59.5 Right 50
491 19:50 N2 53 59.5 E112 07 00.4 Right 50
492 19:53 N2 53 58.4 E112 07 08.2 Left 5
493 19:54 N2 53 56.9 E112 07 10.5 Left 10
494 19:56 N2 53 52.5 E112 07 15.8 Left 20
495 19:57 N2 53 52.0 E112 07 16.8 Left 10
496 19:58 N2 53 51.3 E112 07 18.4 Left 20
497 19:59 N2 53 50.9 E112 07 20.3 Left 20
498 19:59 N2 53 50.8 E112 07 21.3 Left 20
499 20:00 N2 53 50.7 E112 07 22.0 Left 50
500 20:00 N2 53 50.6 E112 07 22.8 Left 50
501 20:01 N2 53 50.7 E112 07 24.4 Left 100
502 20:02 N2 53 51.4 E112 07 27.0 Left 20
503 20:03 N2 53 52.1 E112 07 28.6 Left 20
504 20:05 N2 53 54.3 E112 07 31.8 Left 20
505 20:06 N2 53 55.2 E112 07 33.3 Left 50
506 20:07 N2 53 56.3 E112 07 35.0 Right 10
507 20:07 N2 53 56.6 E112 07 36.2 Right 50
508 20:08 N2 53 57.0 E112 07 37.0 Right 20
509 20:08 N2 53 57.4 E112 07 38.1 Right 50
510 20:08 N2 53 57.6 E112 07 38.4 Right 100
511 20:09 N2 53 58.3 E112 07 38.9 Left 100
512 20:10 N2 53 59.8 E112 07 40.7 Left 30
513 20:10 N2 54 00.3 E112 07 41.6 Left 20
514 20:11 N2 54 00.7 E112 07 42.5 Right 30
515 20:11 N2 54 00.4 E112 07 43.5 Right 30
516 20:12 N2 54 00.7 E112 07 44.5 Right 30
517 20:13 N2 54 01.4 E112 07 46.5 Left 50
518 20:13 N2 54 01.7 E112 07 47.6 Right 100
519 20:15 N2 54 02.0 E112 07 51.1 Left 50
520 20:16 N2 54 02.2 E112 07 54.9 Left 50
521 20:17 N2 54 02.2 E112 07 55.6 Right 50
522 20:18 N2 54 02.4 E112 08 00.5 Left 50
523 20:19 N2 54 02.2 E112 08 01.1 Right 50
524 20:19 N2 54 02.0 E112 08 01.9 Right 50
525 20:19 N2 54 01.8 E112 08 02.5 Right 50
526 20:21 N2 54 00.6 E112 08 06.5 GGG 50 EACH
527 20:21 N2 54 00.2 E112 08 07.1 Right 50
528 20:21 N2 53 59.7 E112 08 07.8 Right 50
529 20:22 N2 53 59.1 E112 08 09.0 Left 30
530 20:22 N2 53 58.6 E112 08 09.6 Left 50
531 20:23 N2 53 57.9 E112 08 10.1 Left 50
531 20:23 N2 53 57.7 E112 08 10.2 Left 50
533 20:23 N2 53 56.9 E112 08 10.7 Right 50
534 20:24 N2 53 55.7 E112 08 11.3 Right 50
535 20:24 N2 53 54.7 E112 08 11.6 GGG 50 EACH
536 20:26 N2 53 50.3 E112 08 11.8 Right 100
537 20:27 N2 53 49.2 E112 08 10.9 Right 150
538 20:28 N2 53 47.3 E112 08 08.7 Right 50
539 20:29 N2 53 46.7 E112 08 07.4 Right 100
540 20:30 N2 53 46.4 E112 08 06.2 Left 100
541 20:31 N2 53 44.9 E112 08 04.2 Right 100
542 20:36 N2 53 47.3 E112 07 57.8 Left 50
543 20:38 N2 53 48.2 E112 07 56.8 Right 250
544 20:39 N2 53 48.2 E112 07 55.8 Right 100
545 20:39 N2 53 48.1 E112 07 54.6 Right 50
546 20:39 N2 53 48.0 E112 07 54.1 Right 50
547 20:39 N2 53 47.9 E112 07 53.4 Right 50
548 20:44 N2 53 48.8 E112 07 54.0 Right 50
549 20:45 N2 53 48.6 E112 07 54.3 Right 50
550 20:46 N2 53 48.0 E112 07 52.9 Right 50
551 20:48 N2 53 45.8 E112 07 50.4 Left 100
552 20:48 N2 53 44.6 E112 07 49.7 Right 50
553 20:53 N2 53 41.7 E112 07 47.0 Right 50
554 20:54 N2 53 39.4 E112 07 45.9 Left 20
555 20:55 N2 53 37.6 E112 07 44.8 Right 50
556 20:56 N2 53 35.6 E112 07 44.2 Left 50
557 20:57 N2 53 32.5 E112 07 43.6 Left 100
558 20:57 N2 53 29.5 E112 07 43.2 Left 50
559 20:58 N2 53 27.2 E112 07 43.0 Left 150
560 20:59 N2 53 24.8 E112 07 42.8 Left 50
561 20:59 N2 53 23.2 E112 07 42.8 Left 50
562 20:59 N2 53 22.3 E112 07 42.9 Left 100
563 21:00 N2 53 20.3 E112 07 43.1 Left 150
Egrets arriving to roost for the nite, initial count of 300 increases to 500 by the time the sun set.
Duffy and Liza at the front, Duffy as a spotter with his 20/20 vision and Liza busy as a recorder. Anura and Musa at the back.
We completed the 1st CFZ in the Mukah area, perhaps the southernmost reach of our CFZ Survey of Northern Sarawak. We were informed by Liza that there are many smaller rivers around Mukah that may harbor better irefly populations. Considering the fairly developed stages of the main Sg Mukah which might explain the less than favorable numbers along some stretches, it might be worthwhile checking out the smaller less developed tributaries for congregating fireflies on another more opportune visit. In most parts, inland area surrounding Mukah has been converted to oil palm plantations many years back, our chances are probably better on the smaller undisturbed sections of rivers closer to the coastal areas.
Write-up, maps and firefly images by Musa Musbah/MNS Miri
Editing and other images by Nazeri Abghani/MNS Miri
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