This document was produced by MAFF as a specific response to the FMD outbreak in the UK in 2001 and was made available on their website. Risk Assessments and specific recommendations related to the conditions in the field at the time and should be viewed in this context as they may not be applicable to outbreaks occuring under different circumstances.
Foot and mouth disease
23 April 2001

MAFF: Veterinary Risk Assessment: What is the risk of migratory geese spreading foot and mouth disease virus?

Background

1. There are three main species of migratory geese which need to be considered. These are barnacle geese, pink footed geese and greylag geese. These geese are due to migrate northwards in mid April and any risks they pose need to be considered. In some areas there are smaller numbers of resident geese, especially greylags.

Goose behaviour patterns

2. There are two main populations of barnacle geese which over winter in Scotland. The Greenland population which breeds on the east coast of Greenland and winters on the west coast of Scotland (and Ireland in smaller numbers) and the Svalbard population of barnacle geese which over winters on the Solway Firth. Although these are the same species there is little intermingling and they are effectively two separate populations. The Svalbard geese number about 23,000. They arrive on the Solway at the end of September and start to move North any time from the end of April to the middle of May. These geese fly North to Helgeland, a group of small islands off the West Norwegian coast, where they stay for about a month before travelling further northwards to the island of Svalbard. Given favourable conditions, that is a good state of nutrition and southerly or south westerly winds the geese will normally make the journey to Helgeland in one go, a journey of approximately 40 hours. Small numbers land on reserve areas on the East and North East of Scotland, such as the Montrose Basin and the Loch of Strathbeg in Aberdeenshire.

3. The Greenland population of Barnacle geese winter on offshore islands off the West Coast of Scotland (with the largest concentration on Islay) before making the return migration via Iceland and onto Greenland. There are about 54,000 individuals in this population with about 33,000 on the island of Islay.

4. The greylag and pink footed geese which winter in far greater numbers (approximately 230,000 pink footed geese and 80,000 greylag geese) winter in the coastal areas of eastern Scotland, Lancashire and Norfolk. None of these areas are heavily infected with FMD at the time of writing, though smaller numbers of pink footed geese winter in Southwest Scotland close to the Infected Area and certainly within the At Risk Areas. These geese make their way back up the East Coast on their way to their summer nesting sites in Iceland and Greenland (pink feet only). They do not frequent the Solway in large numbers (approximately 5 to 10,000).

5. During their winters in Lancashire and Norfolk greylags and pink feet have a preference for feeding on arable land during the autumn where they are able to find waste carrots and other vegetable matter. In January greylags and pink feet in Norfolk begin to move northwards travelling through Fylde, the Solway and east central Scotland reaching Grampian and the Moray Firth by mid March before returning to Iceland and Greenland .

6. The geese which are of greatest interest to us are the Svalbard population of barnacle geese. Although these are in the Solway close to the most heavily infected areas they do not range far from the coastline where they roost. They do not fly far inland to feed during the day preferring to graze on fields adjacent to the coast. They roost at night on the coast of the Solway.

The Northumberland Report

7. The report of the inquiry into the 1966-67 FMD outbreak discussed the possible role of birds in spreading FMD virus. It drew attention to a report that the virus had been recovered from the feathers and feet of a bird contaminated up to 91 hours previously. It also cited a report that suggested that the virus could be carried and shed from the digestive tract of starlings for 10-26 hours. There is no information available for geese but it is worth noting that gut passage time in geese can be as short as 20 minutes. The report also suggested that birds which are carrion eaters might have a greater chance of spreading infection.

8. Having discussed the possible risks associated with birds that section of the report concluded that Danish outbreaks previously presumed to be associated with bird migration could not be related to migration patterns.

Factors reducing the risk

9. Geese are not carrion eaters. They eat young grass, winter cereals, waste grain and other vegetable matter.

10. In order to make the return migratory flight plumage of the geese has to be in very good condition. In the early spring the geese spend a lot time washing themselves in sea water and areas of standing fresh water to ensure that their feathers are clean and free of extraneous debris.

11. Geese prefer pasture which has abundant young grass growth and tend to avoid fields with cattle, though they will graze in fields with sheep. Pasture that has been fertilised recently is particularly favoured.

12. The Greenland population of barnacle geese is not in an infected area and all the population winters in the current Provisionally Free Area. Barnacle geese on the West Coast are not likely to have come from the Solway.

13. The majority of pink footed and greylag geese will not have come from heavily infected areas, though some do winter in Infected and At Risk Areas.

14. Geese also tend to avoid areas near farm buildings or roads (and other boundary features on farms) where disturbance from people and vehicles occurs.

Factors increasing the risk

15. The WWT and SNH reserves at Caerlaverock are surrounded by infected farms.

16. Geese tend to graze in large flocks, the size of the flock increasing the opportunity for picking up and depositing infected material.

17. Geese could potentially spread the virus by mechanical transmission of contaminated mud or manure adhering to their feet or plumage.

18. Geese might carry virus in the digestive tract which could be shed on pasture although no evidence is available to confirm this.

Conclusion

19. The risk of geese spreading FMD virus is very low mainly because of the birds' natural behaviour. The key points are that the geese have to keep themselves clean in order to migrate successfully and the high probability that most of the geese will not come into contact with susceptible livestock.

Acknowledgements

20. The information in this risk assessment was gleaned from conversations with Gill Hartley (SASA), Rick Goater (Montrose), Andy Douse (SNH) John Doherty (WWT Caerlaverock) and Peter Cranswick Co-ordinator of WEBS (Wetland bird survey).

DR M H LAMONT
Deputy Veterinary Head of Team
SERAD
Pentland House

April 2001