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1. Purpose:
Purpose of recording the location of ‘bird flocks’ is to collect information about the relationship between plants and birds. (HKBWS ECF fund project: Studying Landbirds in Important Bird Habitats of Hong Kong, especially in the IBAs)

2. Method:
2.1 Recorder will mark down the location of ‘bird flocks’ which are considered to be important to indicate the relationship to the flowering or/and fruiting plants during the bird surveys along the transect.

2.2 We use seasons to define the different period of ‘bird flocks’.
December to February      : Winter
March to May                    : Spring
June to August                 : Summer
September to November  : Autumn

3. Definition:
For the definition of ‘bird flock’, we will consider the birds as a ‘bird flock’ when they move together across one to three tree canopies, no matter they are the same or different species1. A flock of birds in-flight in open area will not be recorded except raptors, swifts and swallows. Therefore, only when there is a significant number of birds will be considered as “bird flock” during the surveys.

4. Definition of ‘bird flock’ in terms of numbers of birds in group:
Size of bird flock, we define three levels of “bird flock” for different sites.

Sites I - IV / well-wooded area including woodland & scrubland
I)   Tai Po Kau Nature Reserve                       
II)  Shing Mun Country Park       
III) Ng Tung Chai       
IV) Tai Mo Shan

Small - 10 to 20 birds/individuals
Median - 21 to 40 birds/individuals
Large - 41 or above birds/individuals

Sites V - VI / open area including farmland & habitats in wetland
V)  Mai Po and surrounding area
VI) Kam Tin

Small - 20 to 40 birds/individuals
Median - 41 to 80 birds/individuals       
Large - 81 or above birds/individuals       

Note:
The definition of ‘bird flock’ is drawn from the discussion within our HKBWS survey committee where professional experience and different situation among the sites were all being considered.

For map illustration;
Blue line = survey route/transect
Point = survey point section

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Above maps showing the ‘bird flocks’. You may find that there are several hotspots for birds. These hotspots reflect the preference of birds and their hunting areas and even the health of vegetation. That is the possible reason why you always find the similar flock of birds in the same or near area when you do bird-watching in Tai Po Kau. Hence, the hotspots of ‘bird flocks’ are usually referred to the hotspot of bird-watchers.
Also, ‘bird flocks’ were disappeared after March. That is the season the adults begin to breed and find their partner. ‘Bird flocks’ began to appear in the final week of July and flocks of mixed species (like winter bird flocks) including adults and juveniles can be found. Early migrants can be found in these kinds of mixed bird flocks.

For people who are interested in the details of “Studying Landbirds in Important Bird Habitats of Hong Kong, especially in the IBAs”. You may download the attached pdf file for the Bird Survey Manual.