334 Proceedings of the Association of Applied Biologists

FEARE, c. J., DUNNET, G. M. & PAITERSON, I. J. (1974). Ecological studies of the rook (Corvus frugilegus L.) in north-east Scotland. Food intake and feeding behaviour. Journal of Applied Ecology 1 I, 867- 896.

FISHER, J. (1948). Rook investigation. Journal of the Ministry of Agriculture and Fisheries 55,20-23. PATTERSON, I. J., DUNNET, G. M. & FORDHAM, R. A. (1971). Ecological studies of the rook (Corvus

frugilegus L.) in north-east Scotland. Dispersion. Journal of Applied Ecologv 8,8 15-833.

Goose damage to agricultural crops in England

BY E. N. WRIGHT AND A. J . ~SAACSON

MAFF Pest Infestation Control Laboratory, Tangley Place, Worplesdon, Guildford, Surrey

To the majority of people in England the sight of wild geese is something of a novelty; yet to a few, who farm land adjacent to estuaries and lakes, certain species are becoming a source of real concern. Geese are primarily grazing animals and where they feed on pastures throughout winter they are often accused of robbing stock of the ‘early bite’ (Kear, 1970). Winter cereals are also attractive to geese and extensive grazing can reduce yields through loss of leaf area and, more importantly, compaction (puddling) of the ground. But agricultural damage is not restricted to grassland and cereals; root crops are also attacked and there are fears that geese may be changing their feeding habits to take advantage of new agricultural developments, such as the extension of carrot growing in Lancashire. Three species of geese are currently troublesome in England and it is convenient to consider each separately.

Pink-footed goose (Anser brachyrhynchus) Pinkfeet are winter visitors to Britain, arriving here from their Icelandic breeding grounds in September

and departing again the following May. Most of the 70-80 OOO birds that come here remain in Scotland but some 12-15 OOO now winter in S.W. Lancashire with smaller numbers to be found on the Humber estuary and around the Wash. Geese have wintered in these areas for as long as anyone can remember and in the traditional potato growing district of S.W. Lancashire they fed extensively on waste potatoes left on the fields after harvest. However, in recent years two important changes have occurred. Firstly, there has been a population build-up of pinkfeet in S.W. Lancashire since 1972 (Fig. 1) associated with a declining use of haunts on the Humber and the Wash (Ogilvie & Boyd, 1976). Secondly, potato growing has begun to give way to the more profitable carrot crop, of which c. 1200 ha are now grown in Lancashire. During the winter of 1973-4 geese were reported attacking growing carrots, eating the foliage and pecking into the crowns but, because this information only came to light some time after the attacks took place, it was diflficult to ascertain the real extent and significance of the damage. Some people suggested that only frosted carrots had been attacked but no evidence to confirm or refute this was obtained. Also, on investigation, it was found that there was damage by other species, notably pheasants (Phasianus colchicus) and hares ( L e p s europaeus), which confused the issue and made a satisfactory assessment impossible. Although only four out of 138 carrot growers had experienced damage, in view of the importance of the industry and the fear that damage might spread in future years it was decided to mount a more thorough investigation in the 1974-5 season.

Observations began in November 1974 and covered an area of c. 16 OOO ha with more intensive study of two areas, totalling c. 3340 ha, which were most frequently visited by geese. Monthly visits, each lasting 5 days, were undertaken to estimate goose numbers, observe behaviour and identify food sources. About 770 ha were under carrots (averaged field size 4.9 ha); other main crops being brassicae (2835 ha), potatoes (2025 ha), pasture (1012 ha) and miscellaneous market garden crops (607 ha). However, the most important feeding areas for geese were the 7700 ha of cereal stubble and the post-harvest potato fields as these became available. The autumn of 1974 was exceptionally wet, with the result that ploughing of stubbles did not begin until the New Year and the lifting of both carrots and potatoes was delayed. Population counts put the number of pinkfeet feeding in the area at a maximum of 7600 birds; somewhat fewer than estimates by other observers. During November geese fed exclusively on stubbles; in December mainly on stubbles with some waste potatoes and in January mainly on potatoes with some stubbles. In February the majority migrated and observations ceased.

Throughout the period only one case of damage to growing carrots was reported. This occurred on the night of 30/31 December at a site near the Martin Mere reserve and the warden was able to record the

Proceedings of the Association of Applied Biologists 335

sequence of events in some detail. The carrots were growing adjacent to a plot of harvested potatoes; geese started feeding on waste potatoes on 26 December and by 30 December, when a large proportion of the carrots had also been harvested, they had moved onto the carrot field. By evening on 30 December five rows of carrots remained unharvested and it was these five rows that suffered damage durirg the night. At 07.00 h the following morning about 4500 geese were flushed from the field and that day, despite obvious damage to the carrot tops, the grower successfully harvested the damaged rows and expressed satisfaction with the crop. Counts of waste carrots on the surface of the freshly harvested part of the field showed a mean density of 38.8/m2 whereas the area which had been fed over by geese had a mean of only 1 .6/m2. This suggests that geese had been mainly attracted to the waste carrots and any interest in the growing crop was incidental.

In view of the fact that 1974-5 had been a rather exceptional season climatically the observations were repeated in 1975-6. A similar pattern of visits was followed, from October to February, and population counts were again combined with observations on food preferences and availability. By contrast with the previous season 1975-6 was exceptionally dry; cereal and potato harvests were taken early and the land ploughed, and in some cases replanted, before the geese arrived. Studies were concentrated in the two

r

1963 1966 1969 1972 1975

Fig. 1. Changes in numbers of dark-bellied brent geese in S.E. England (0) and pinkfooted geese in S.W. Lancashire (0) from 1963 to 1975. Data from censuses organised by the Wildfowl Trust.

main areas used by geese the previous season and, to assess food availability, 5 x 1 mile transects were done monthly in each area. The crops in all fields adjacent to the road were recorded and this provided both an index of land use and a pattern of seasonal change. The sample thus examined constituted 142 fields covering a total of 635.5 ha; this represented 19% of the two study areas and 4% of the total carrot- growing area. Since the primary interest rests in the availability of food for geese, rather than the absolute cropping pattern, results have been simplified for presentation by plotting potential feeding areas (as judged by the observer) as a percentage of the whole (Fig. 2). At the beginning of the season c. 70% of both study areas could provide food for geese but by February this had been halved and it can be seen that the available feeding area dwindled more rapidly in area A than area B. This possibly explains why, as the season advanced, geese showed a marked preference for area B. In November the acreage of growing crops, including pasture, represented only about 20% of the total

area and this had declined to 10% by February. However, throughout the study, growing crops represented about 30% of the potential goose feeding area yet the numerical distribution of geese by different feeding sites (Table 1) shows that arable crops were largely eschewed in favour of pasture and post-harvest gleaning on cereals, potatoes and, to a lesser extent, carrots.

The number of geese feeding within the carrot-growing area in 1975-6 was slightly larger than in the previous year; the peak of 8673 being recorded in December. The majority again departed before the end

336 Proceedings of the Association of Applied Biologists

1 I I I I

Nov. Dec. Jan. Feb. Fig. 2. Percentage area of two study sites in S.W. Lancashire with food for geese: November 1975- February 1976. Total food resources: 0, Area A; A, Area B. Growing crops only: 0, Area A; A, Area B.

of February and many left earlier. As in the previous season, only one case of damage to carrots was reported and that occurred in December. A field of carrots of 3.2 ha had been partially harvested when geese arrived and damaged 1.4 ha beyond profitable redemption. The farmer reported that the harvested part of the field had yielded around 50 t/ha of washed carrots. The ruling market price at the time was about &70/t, thus the value of the lost crop was of the order of E4900 gross. Observers estimated that about 2750 geese had visited the field and the damage was done in the course of only a few days. Several other carrot fields were known to have been visited by geese but any damage was insignificant.

Table 1. Monthly totals and distribution by crops of pinkfeet feeding within the carrot-growing district of S. W. Lancashire, October 1975-February 1976

Growing crops Pasture Cereals Potatoes Carrots

Post-harvest Cereals Potatoes Carrots

All others Totals

Oct.

2973 0

271 0

830 0 0 0

4014

Nov.

1700 0 0 0

4644 110

0 0

6454

Dec.

1351 0 0

1372*

133 1 3247 1372.

0 8673

Jan.

457 10 0 0

0 2872 502 100

394 1

Feb.

432 0 0 0

0 587

0 15

1094

* One flock of 2744 geese feeding on a partially harvested carrot field. Numbers arbitrarily divided between the growing crop and harvested area.

The conclusion to be drawn from the observations made during these two winters, under totally different conditions of weather and agriculture, must be that wild geese are currently responsible for only a small amount of damage to growing carrots in S.W. Lancashire. However, it has been shown that damage does occur to healthy carrots and is costly when it happens. Partially harvested fields have proved the most vulnerable and farmers would be well advised not to leave fields in this state. If attacks were to increase in frequency, and the prediction is for further growth in the pinkfeet population (Ogilvie & Boyd, 1976), then goose damage t o carrots would become a major problem.

Dark bellied brent goose (Branta bernicla) This race of the brent goose breeds in arctic Russia and, like the pinkfoot, occurs in Britain only as a

winter visitor. It is a small goose which prefers to feed on Zostera and Enteromorpha in estuaries and

Proceedings of the Association of Applied Biologists 337

marshes and is found mostly in S.E. England from the Wash to Chichester harbour; the largest concentration being on the coasts of Essex and Suffolk. Following the collapse of its natural food supply in the 1930’s the British population of brent geese dwindled in numbers and, in an attempt to arrest the decline, it was taken off the shooting list and given full legal protection. Regular population counts began in the 1960’s and for the next decade numbers remained roughly constant a t about 15 OOO wintering birds. However, since 1970, following a series of good breeding seasons, numbers have increased sharply and now stand at around 40 000 (Ogilvie & St Joseph, 1976) (Fig. 1). Unfortunately this increase in numbers has not been matched by an increase in natural food and over the past 5 years brent geese have been increasingly driven to feed on farmland where they graze pastures and winter cereals. There are currently no complaints of damage to root crops.

Brent geese were first noted feeding on farmland in the winter of 1972-3 but numbers were few and there were no complaints of damage. The following year (1973-4) geese visited farms in greater numbers and ADAS agronomists estimated that 109 ha of winter cereals had been badly damaged, including 28 ha of winter wheat at one site. During the same season I. R. Deans (personal communication) compared grazed and ungrazed plots at a site adjacent to the sea wall on Foulness Island; he found plant density to be unaffected but fewer ears per plant and a 44% difference in yield between severely grazed and control plots. Effects of this magnitude may be exceptional but this study showed the need for further work.

In the summer of 1974 brent geese had a disastrous breeding season and almost no young survived to reach Britain in the autumn (Ogilvie & St Joseph, 1976). As a result, goose numbers were down 20% and, presumably because of this, grazing pressure on cereals was slight. Only one case of damage was reported and plans to investigate damage more thoroughly had to be postponed.

The 1975 breeding season was a good one for brent geese and the population wintering in Britain, estimated at 49000 birds, was the largest on record (Ogilvie & St Joseph, 1976). The first reports of damage were received in December and by the end of the season geese were known to have visited 48 farms, although only 29 farmers complained of damage. The pattern of damage was similar to that previously observed, with geese firstly grazing pastures and then moving on to winter cereals, and arrangements were made to measure the effects on yields at six sites. To avoid the complications usually associated with experimental exclosures, damaged and control areas were identified by inspection and demarcated with stakes. At harvest time random samples were drawn from grazed and ungrazed areas using two different techniques. Although the results have yet to be fully processed they indicate differences due to grazing ranging from a slight gain (0.5%) to a considerable loss (33%) of yield compared with controls.

The effect that a given amount of goose grazing will have on yields is influenced by many factors; especially the stage of growth of the crop at the time of attack, the intensity of grazing, the soil type and the weather. Most farmers and agronomists agree that grazing per se does little harm and may even be beneficial, as long as the meristem remains undamaged. In practice this means that light to moderate grazing during early or mid-winter is unlikely to be significant but heavy grazing, especially late in the season when plants may have started active growth, can be harmful. But loss of leaf area is only one aspect of grazing; geese often bunch tightly together when feeding and under wet conditions, especially on heavy land, ‘puddling’ occurs with resultant retardation of growth; conditions that are dimcult and expensive to rectify.

Damage by brent geese to cereal crops is a recent problem. It has its origins in the growth of the goose population coupled with changes in the natural and farmland habitats. The damage assessments carried out by MAFF in 1976 were made in one of the driest years on record; even so yield reductions of up to 33% were recorded. With advance reports that the brent have had another good breeding season and the expectation that, sooner or later, we shall have a wet winter the conflict between agriculture and conservation seems bound to intensify.

Canada goose (Branta canadensis) This is the largest of the three species considered here and, unlike the other two, is resident and mostly

sedentary. Canada geese were probably first introduced into Britain about three centuries ago and introductions from America have continued up to recent times. The entire British population can therefore be regarded as comprising feral birds and, although they are free-flying, colonies tend to develop attachments to ‘home’ waters. The first census of Canada geese was done in 1953 when the population was found to be about 3000 strong (Blurton-Jones, 1956). Since then they have increased considerably

338 Proceedings of the Association of Applied Biologists

and the most recent estimate puts their numbers at about 18OOO (M. A. Ogilvie, personal communication).

Complaints of damage to agricultural crops are of long standing and on estates where the geese have been deliberately introduced this is not infrequently a source of friction between landlord and tenant. The nature of the damage is similar to that done by other species of geese and most complaints relate to grazing of pastures or cereals during winter and spring but, being resident throughout the year, they also sometimes attack ripening crops before harvest.

Although Canada geese are widely distributed throughout Britain they are particularly numerous in the Midlands and it is from that area that most complaints of damage are received. In an attempt to get the situation in perspective PICL has initiated a study of Canada geese in relation to farming in the West Midland Region. Changes in population size and movements of colour marked buds are beiig studied in addition to assessments of damage and a survey of crops at risk, i.e. crops adjacent to waters known to carry geese. It is hoped that the results of this study will permit the formulation of a policy for the management of Canada geese in order to minimise damage to agricultural crops.

We wish to thank the numerous people who have contributed information or assisted in other ways, especially Regional staff of the Ministry of Agriculture, who helped with field work, and farmers who allowed observers on their land.

R E F E R E N C E S

BLURTON-JONES, N. G. (1956). Census of breeding Canada geese 1953. Bird Study 3, 153-170. KEAR, J. (1970). The experimental assessment of goose damage to agricultural crops. Biological

OGILVIE, M. A. & BOYD, H. (1976). The numbers of pink-footed and greylag geese wintering in Britain:

OGILVIE, M. A. & ST JOSEPH, A. K. M. (1976). The dark-bellied brent goose in Britain and Europe, 1955-76.

Conservation 2,206-2 12.

observations 1969-1975 and predictions 1976-1980. Wik@owl27,63-75.

British Birdr 69,422439.

The creation and management of wildfowl &ges as a means of the coaflict between farmers and m e

BY MYRFYN OWEN The Wildfowl Trust, Slimbridge, Glos. GL2 7BT

A B S T R A C T

With increases in goose numbers and incidences of problems with other than traditionally damaging species on new crops contlict has greatly increased recently.

This paper suggested that the creation of managed goose refuges in problem areas provided the best long-term solution. Examples of the success of refuges were given based on experience at two Wildfowl Trust goose refuges. Goose use of land surrounding these refuges had decreased following their creation and the goose carrying capacity of refuge land had been increased by up to 150% by controlling winter disturbance, cropping and stock grazing. This had been achieved without drastically changing the agricultural regime, which in both areas was in line with local practices.

Because of great annual fluctuations in goose numbers following variations in breeding success and of the dimculty of predicting goose carrying capacity, assessments of the area of land required to accommodate geese in conflict with agriculture in Britain can only be very approximate. Based on goose counts in 1975-6, some 150000 geese (of four species) were potentially involved and the land area required as refuges to accommodate all of them (giving a maximum figure) in the region of 20 000 acres (7800 ha).