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Harrier Roosts - Arrival routes - Nong Lom

Nong Long Harrier Roost Main Arrival routes NE - Pink, NW - Yellow and W-WNW - Green Pa Mak No Roost is shown to the NW. A few are seen to arrive from the WSW. Birds arriving, pink route east side are unseen as the light fails SW - East It is likely that birds arriving from this direction would not be seen, however at the odd time we have counted on the eastern border, few have been noted.

Combined = Is the total estimated for the 3 roost (Pa Mak No and Little England).

Notes.

30 12 07: Pa Mak No, harriers. 200 harriers were seen here this evening. Interesting is that as we have two large harriers roosts within 3 km of each other, is the interaction between birds passing over the Pa Mak No roost, on route to Nong Lom. The chattering conversation started at 17.40 and continued to 17.55 at that time around 50 birds moved south to Nong Lom, others departing during the chattering period. It does seem that there is an attempt to encourage the Pa Mak No harriers to move, but if this is so it seems to fail as at 18.00 the roost count was at least 175. Birds arriving at high altitude in a stalling glide from the west and many males streaming in low from the pre roost to the east. Amazing.

The social interaction between these birds may well be important to study. Harriers in they're daily hunting are solitary, yet they're behavior at roost is complex, they are very social and un-aggressive towards each other. However they do make a lot of noise with the chattering calls. Breeding display has not be observed, however some birds do a form of abbreviated sky dance, just a hint really. In away it's all a bit like going to a party, no ones dancing, but once somebody takes the floor, others join in. So Tonight was a big party - happy New Year from Yonok.

20th Nong Lom Harrier Roost Count and estimated total for the two Yonok roosts. Nong Lom 20th: 205 arrived from the SW- WNW and 42 from the NW = 247 + Estimated unseen birds 100 = 347

The estimated total for Nong Lom is 347 and with the previous nights total roosting at Pa Mak No of 97. Makes a grand total of 444. This is a fairly accurate estimate, based on the fact that I counted 85 at Pa MAk No moving south to Nong Lom yesterday, from my position there I cannot see the main route, if we had have been in a position to count in the North Fields, I expect the number to have been around 120-140.

The increase in numbers is probably due to experience of counting and that the Little England roost has not had birds for 6 weeks now, so presume they have moved to Pa Mak No

97 Harriers roosted and 85 flew south to Nong Lom, intersecting was that all the Nong Lom past low over the Pa Mak No roost. 183 Harriers were seen in total. The Red-throated pipit roost of about 600 birds is in the same area as the Harrier roost. A passing Buzzard caught a pipit and was mobbed by several Harriers. The Harriers never prey on the pipits and do not harass the grass owls, interesting that these three species can live together in peace, actually the only aggression I have noted by Harries is if any raptors come to close to the roost and are quickly seen off. The Harriers must see the grass owls as they pass low over the bog, however they never flush them. the only time I have see a Grass Owl put up was by a Drongo.

16th; Nong Lom Harrier roost; Harriers arrived very late this evening, bed time is normally 5.55. The peak arrival time tonight was 5.50 - 6.03. I recorded a no count as we only counted in 140, at 6pm large numbers of Harriers were still arriving in almost complete darkness. This roost in the past has proved impossible to count on a single night as one cannot see the birds arriving from the north, I also noticed that a large number came in from the south, this is not a regular root and we missed them.

Method of counting; Dowroong counts by eye, all birds arriving between South - NW, however if birds come from due south they are missed, as to distant for the eye. I count with Bins, birds arriving from the NNW - NE as they are mostly distant. I try to keep an eye on the southern approach, but we have found on the previous two counting nights that we have been caught out by birds sudden late arrival and at high altitude. Its possible that this late arrival is due to the moon. The moon is directly overhead and creates extra light, and with clear skies the birds tend to arrive late anyway.