The structure of information for each species keeps to the same format.
The English and Latin names including the sub-species/race that occurs in Northamptonshire. If more than one distinct subspecies occurs from which most individuals can be identified then the commonest subspecies will be described first followed by the other subspecies in brackets. Good examples of this are White-throated Dipper Cinclus cinclus gularis/Black-bellied Dipper Cinclus cinclus cinclus, Common Teal Anas crecca crecca/Green-winged Teal Anas crecca carolinensis and Common Chiffchaff Phylloscopus collybita collybita/Siberian Common Chiffchaff Phylloscopus collybita tristis. Where more than one subspecies occurs but individuals are not readily identifiable then they are grouped together. Examples of these are Merlin Falco columbarius aesalon/subaesalon and Goldcrest Regulus regulus anglorum/regulus.
Feral species are denoted with (C) immediately after the English name. This is a reference to the British C list that includes all species that have feral populations in Britain.
In capital letters underneath the English and Latin names is the current status of each species relating to Northamptonshire.
There are seven general levels of status that are defined in more detail for each species:-
Sedentary: A species showing no notable movement linked to any normal circumstances. E.G. Time of year or weather.
Resident: The majority of birds do not leave the county or are replaced by others. The population does not change much, movements may be altitudinal, climatic, sex E.G. European Robin or age E.G. Tawny Owl.
Summer Visitor: These birds are presumed to breed or hold territory.
Winter Visitor: These birds stay for the majority of the winter and are not just present because of adverse weather conditions.
Passage Migrant: These birds are normally associated with spring or autumn migrations, but with some species this can be hard to define.
Visitor: The presence of these birds is not associated particularly with spring or autumn migrations. They are not present at any particular time of year.
Vagrant: Occurrences of these species are accidental. Wreck Vagrants are only normally recorded inland as a result of severe weather conditions. Rare Vagrants are all British rarities so their presence in the British Isles is also accidental.
For most species classified as vagrants there will be a bracket containing numbers accompanying the heading in two formats:
1) All Vagrants will have two numbers in brackets after the Latin Names, the first relates to how many records there have been in Northamptonshire and the second number refers to how many individuals have been involved. E.G. (12-23) A few old records did not specify how many individuals were seen. For these records it has been assumed that one individual was involved and for each of these records in question this is commented upon in the text.
2) All British rarities have been classed as Rare Vagrants and so the single number next to their status refers to how many of this species have been seen in Britain E.G. (213)
Records of vagrant species can be found in Vagrant Data. The classification of a species as a vagrant is somewhat arbitrary but the limit given here is that of about forty records or less. A few species that are vagrants are not in the Vagrant Data for a variety of reasons, mainly the lack of detailed records, E.G. some Geese and several sub-species.
Other species that do not fit into this category but whose specific records are note-worthy can be found in Vagrant Data. These records are in two categories:
1) Species noted commonly before 1900 but whose records have become very scarce in the twentieth century.
2) Species noted commonly before 1969 but whose records have become very scarce in the last twenty-eight years.
The text for each species follows these guidelines:
a) The text starts with a statement about the species distribution in Britain, the Western Palearctic or the World. This is taken from a view point firmly with Northamptonshire in mind, so only distribution and movements that might affect a species being recorded in Northamptonshire are referred to and certainly not that species distribution in Western Palearctic or World terms, unless of course that is necessary.
b) The birds status in Northamptonshire in terms of distribution and numbers.
c) Breeding status past and present.
d) Habitat preferences.
e) The species status historically with reference to Morton and Lord Lilford. If Morton is referred to then the date that should be assumed is 1712 and if Lord Lilford is referred to, then assume 1895.
f) Any note-worthy records
g) General text including arrival or migration patterns etc.
h) Inclusion in the Northamptonshire Red Data Book and the reason for this inclusion.