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Subject: Weather and Earliest Spring/Autumn Records [Print This Page]

Author: wgeoff    Time: 19/07/2010 16:53     Subject: Weather and Earliest Spring/Autumn Records

This note refers to the article on page 14 of the latest HKBWS Bulletin number 216. Some members have asked for a list of the species recorded and the basic information used.

The following Excel file has data sheets for both the spring and autumn records for all the species recorded (Earliest Spring and Earliest Autumn) as well as HKO Average Daily Temperature data (Spring Temp and Autumn Temp).

The following codes may appear in the cells

x = no records for that species in that year
nsp = no spring records for that species in that year
nau = no autumn records for that species in that year
su = species over-summered in that year
dates in bold are the current earliest records for that species (as at the end of 2006)

Otherwise, the cells contain the day and month of the earliest spring or autumn record as it appears in the HKBWS Annual Report for the year given in the column head. The 2005/6 records are taken from a preview of the 2005/6 Annual Report.
(Note the actual cell record often appears as the year ‘2008’. This is done so that Excel can correctly calculate statistics across different years. The actual year is that given in the column head)  

The data was basically prepared for the 2005/6 Annual Report and part of it will be reproduced there when it is published. The background behind the choice of species is given in the Bulletin.
The relationship between Earliest Records and Average Temperature was found by chance after the basic data was prepared.

If you find any errors in the data, please send me a PM  

The graphs, which are rather small in the Bulletin, are reproduced here in larger size

This analysis suggests that the colder the weather, the earlier migrants arrive in Hong Kong, in both spring and autumn. Whilst this might be expected in autumn, the opposite could be expected in spring – until the effects of spring cold fronts are included.

I produced a similar data set for Latest Spring records but there was no relationship between that and Average Spring Temperatures.

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