Some bird movements can be masked by the seasonality of Atlas surveys. Not all Atlas sites have been surveyed regularly throughout the year. If a bird appears to be absent from an area in any given month, it may be the result of minimal surveying rather than a real absence of species. For example, very few surveys have been completed in central Australia over the summer months. The Birdata maps show survey effort as an optional background layer that can be turned on or off.

Simplified atlas data

The Birdata maps and lists simplify the information in the Atlas database. A bird species appearing in a list may have only been recorded once, while others may have been recorded hundreds of times in that area.

Reporting rate

At the 10" cell level, Atlas distribution maps are displayed according to reporting rate. Reporting rate is the percentage of Atlas surveys that have recorded a particular species compared against the total number of surveys in that cell. Reporting rate provides an indication of how common or visible a species is in a grid cell. Common species that are hard to detect or identify may have low reporting rates. Conversly, any species recorded in cells with very few surveys may have a high reporting rate. Incidental Atlas records are displayed as a separate category on the maps.

Data quality

Atlas data is constantly vetted for positional and bird species accuracy. However, within the 5 million records there may still be some errors on the Birdata distribution maps or in the bird lists.

Atlas data entered through Birdata is not made available to the public until it has been vetted.

More detail

Birdata provides access to the most commonly requested Atlas data. If your research requires more detail than Birdata can provide, please contact the Birds Australia atlas team on 03 9347 0757 or atlas@birdsaustralia.com.au. We are able to provide data that is tailored to your needs (data extraction fees and licencing applies).

Birds Australia also holds other valuable bird monitoring databases including the Nest Record Scheme, Australian Bird Count, Bird of Prey Watch and Birds on Farms.

Birdata help

Maps | Bird lists | Interpreting Atlas data

Search types and sites

The Atlas methodology involves recording the birds seen at a particular time and location. There are three types of Atlas surveys submitted to the database:

• 2-ha Search: this is our preferred method where the Atlasser searches a two hectare area for 20 minutes.
• Area Search: more flexible than the 2-ha Search. Atlassers search any area, listing the birds seen around a central point. These searches can cover a small area within 500 m of the central point, or a large area out to 5 km. The search area can be any shape and the search time can be anywhere between 20 minutes and one month.
• Incidental search: records of rare, uncommon or unusual species, seen as once-off sightings; or surveys of a specific group of birds, such as wetland birds, waders, or waterfowl.
• Fixed Route: Establish a birdwatching route where you intend to conduct repeat surveys at least once every three months. During each survey count all birds you see and hear along the route. Please register your surveys site with the Atlas Project before submitting your data. For a more thorough explanation of this method, see the Birds Australia atlas web page.

All of these search types are recorded as single points in the database - regardless of the area that was actually searched.

Presence, absence, breeding and abundance

At their most basic, Atlas surveys record the presence of bird species. In some cases, no birds at all are seen during a survey. Some surveys include information on bird species that were breeding, and some include estimates of abundance - the number of individuals of a species seen at that time and place.

Survey effort and seasonality

Some Atlas sites are visited repeatedly, building up a picture of the bird fauna over time. Others are one off surveys or sightings.

Survey effort obviously varies across the continent. Areas close to major populations have the most repeat surveys. The Atlas aims to cover every one degree grid in Australia, and special survey expenditions have been conducted to make this a reality.

Some bird species migrate to and from different parts of the continent (or in and out of the continent) at various times of year. Birdata allows you to track these movements by drawing species distribution maps for particular months (try mapping the Swift Parrot from month to month).