March 2018 Roundup

I was trying to get the March round-up before the crazy busy time of Khmer New Year but failed but here it is not too long after the event.

In the mangrove swamp, we saw yet another new (to me) species, and even genus, of orchid. It has not yet been identified to species level. It is a Thrixspermum sp.

 

One day, on our way from Rainbow Lodge to the mangrove swamp, we had to stop off at Tatai bridge to drop off some customers. While we were there, we saw a few swallows: Hirundo tahitica (Pacific Swallow). These are less widespread than the more commonly seen Barn Swallow, and are most seen in coastal areas. They nest under the bridge, along with Silver-backed Needletails.

In a raised clearing (caused by a recent fire) in the mangrove swamp, I accidentally startled a nesting bird. Fortunately, it landed nearby and I was able to take a photo of it and confirm it as a Caprimulgus macrurus (Large-tailed Nightjar). Realising it was a nightjar, and that it was, unusually, nesting out in the open, I searched the ground and found two eggs. Nightjars nest directly on the ground, with no nesting material whatsoever. It seemed odd for the mother to pick such an exposed nesting site. During the month, I was able to see at least one of the parents and one chick (and show them to customers) on multiple occasions. Nightjars are mostly active at dawn and dusk but also during the night, particularly on well-lit nights. During the day, one parent, probably the mother, sat upon the eggs and later the one chick that hatched. Despite the clear white marks on the adult bird, it is extremely well camouflaged on the ground, and she was very hard to find each time, even though I knew roughly where she was. This was made harder by the fact that the chick was in a slightly different place every time we visited the nest site. Given the helpless appearance of the chick, I assumed that the mother was moving it. This supports a view that has been expressed elsewhere but never proven. There is a conflicting view that the chicks can walk around after only a few days. Either way, I suspect that the movement of the first born chick led to the demise of the other egg because the mother could not sit in two places at once.

 

I was also very lucky to stumble upon the nest of a Harpactes erythrocephalus (Red-headed Trogon) – a stunning bird. I knew they were in the area because they had been recorded during bird surveys by Howie Nielsen, a very well respected expert in South-east Asian birds. I had heard them before, the first time with Howie in the jungle at 6:30 a.m. one morning, but had never seen one. I was almost fully recovered from my illness and was bored, so I decided to go for a stroll, which turned into clearing a path that led me directly to the nesting site of the trogon. I would never had known had the bird not decided to fly from its nest hole as I approached. I didn’t manage a shot of the adult the first time but went back later and got the single photo of the father (females’ heads are more brown than red). Red-headed Trogons are mostly active at night, feeding mainly on moths and other nocturnal insects. Both parents help to incubate the eggs and to feed and brood the young but only the female incubates/broods at night.

 

We see quite a lot of bugs from the family Pentatomidae (a.k.a. stink bugs or shield bugs) but I had never before seen one quite like this one, which we spotted on a night walk. It has been identified as Sabaeus humeralis. Pentatomids “shield bug” common name is, obviously, derived from their shield-like shape. The “stink bug” name is based on the strongly smelling chemical that members of this family produce in a gland in their abdomen when they are threatened or injured.

ID Credit: Eduardo I. Faúndez

March provided my first clear sighting of a Pernis ptilorhynchus (Oriental Honey Buzzard). I had seen them before but only in flight and never previously managed a photo. The Oriental Honey Buzzard has a longer neck and smaller head than most birds of prey, which help it to access its preferred food: the larvae of social bees and wasp, and even the comes and honey of bees.

ID Credit: Senglim Suy

Pigeons are often not particularly liked by visitors from developed countries, where they are even considered as vermin but I always try to show them to customers when I can. Here we have several native species of wild pigeons, some of which are quite attractive birds, not least Treron vernans (Pick-necked Green Pigeon). In nature, a pigeon is no more vermin than any other creature. I would go further and say that the concept of vermin does not exist in the natural environment.

Oriolus chinensis (Balck-naped Oriole) is a striking bird but, despite its bright colouring, it is far more often heard than seen. Its call is quite odd and, seemingly, more like the meowing of a cat than the call of a bird. It seems a very nervous bird, not allowing people to get anywhere near it, so, although not the greatest photo, I was pleased to get this shot.

One night we saw the fattest ants I have ever seen. They have been identified as belonging to the Prenolepis genus. These ants are known as “False Honeypot Ants” because they have a similar habit to Honeypot Ants (genus Myrmecocystus) of gorging themselves on sweet liquid until their abdomens look ready to burst.

ID Credit: Vincenzo Gentile

On the same night we also saw a bug with a strange spine, for want of a better word, sticking out from its scutellum. This is the diagnostic feature of the Helopeltis genus, also known as Mosquito Bugs. It is unclear what function the spine performs. It has been suggested that it might contain a sensory organ but Lever (2007) concluded that this is unlikely.  I wonder if the bugs benefit from the spine’s resemblance to the fruiting body of a Cordyceps fungus, which might make it a less attractive meal for predators. This is likely to Helopeltis theivora (Tea Mosquito Bug).

 

During a “nature ramble” we saw some Ardeola bacchus (Chinese Pond Herons) in breeding plumage, with some still in transition. It is quite a transformation from their normal dull, mottled brown appearance.

 

We were lucky enough to get a visit from Senglim Suy (a Cambodian bird expert, who I have been hoping to meet for some time) and two of his friends (Socheat Ly and Pahnavuth Sok). All are very keen birders and photographers and came all the way from Phnom Penh for one night in the hope of photographing the Red-headed Trogon and Large-tailed Nightjar. They didn’t arrive until 17:40 and I immediately took them downriver in an attempt to see a Peregrine Falcon that I had seen roost on a telephone mast. We ended up not making it in time but the guys got some shots of a Ducula aenea (Green Imperial Pigeon), which was a “lifer” for all the guys. This photo was taken in March but not on the same trip because my camera was not able to cope with the failing light, unlike the superb equipment of the guys. Serious camera envy!

It was getting dark but we decided to see if we could find the nightjar. I was tricky driving the boat up the stream, particularly as someone had laid a load of fish/crab traps. The guys were able to see and photograph the nightjar chick but neither parent was around – probably off hunting. So we headed back to Tatai Bridge, where the guys were staying. We had a meal together (way too much crab and chicken) and agreed to meet early the next morning for breakfast.  After breakfast, I took the guys to the trogon nest site and they were able to see the one remaining chick. The set up a camouflage sheet to hide behind and waited for the bird to appear. In three hours of waiting, one trogon flew in but got spook and didn’t land, so at least the guys got to see it, even if they got no photos. On a very tight schedule, they then had only time for some lunch before heading back to Phnom Penh. So not a very successful trip but, in Senglim’s words, “This is bird watching”!

Author: Gerard Chartier

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