T H E M I G R A T I O N O F G E E S E A S A N I N D I C A T O R OF C L I M A T E

C H A N G E IN T H E S O U T H E R N H U D S O N B A Y R E G I O N

B E T W E E N 1 7 1 5 A N D 1 8 5 1

T I M O T H Y BALL

University of Winnipeg, 515 Portage Avenue, Winnipeg, Manitoba, Canada, R3B 2E9

Absl~act. Observations and records maintained by the Hudson's Bay Company at York Factory and Churchill Factory on Hudson Bay between 1714 and 1825, serve as the source of information for a study of changes in the date of arrival of geese as a phenological indicator of climatic change. Changes in the migration pattern of geese are reflected in the changing date of arrival at the same location over a long period of time. Variations in this date are determined to be a function of southerly or tailwinds in the northward spring migration.

At the present time there are many areas of the world and many periods of history for

which no climatic data exists. This is true for both actual climatic data and phenologic

data. The region of Hudson Bay in north central North America is one of these areas. It

is difficult to suggest that one region of the world has any greater climatological importance

than another because it is an open system. The southern shore of Hudson Bay is a region

for which a special case might be made. Situated in the standing wave created by the

Rocky Mountains and also being a large body of ocean penetrating to the centre of a

large continent are two factors. The presence of the tree line between York Factory and

Churchill Factory coincident with the mean location of the Arctic Front make an even

stronger case.

The position of the Arctic Front, its seasonal movement and fluctuations on a longer

term are very direct indicators of changes in the dynamic factors of climatology. Any

information that provides information on these factors should serve to strengthen our

understanding of climatic change.

The records of the Hudson's Bay Company stand as virtually the only written docu-

mentation of events occurring in Central Canada over a majority of the last 300 yr. For

the Company and its employees the climate was a dominating factor in all aspects of its

operations and as a result they made constant references to weather and weather-related

information in their records.

Bird migration

In the second volume of his magnum opus Climate: Present, Past and Future H. H. Lamb

writes,

Records of differences of range that were regularly maintained for some time in the past are therefore of interest to climatology, though they seem unlikely to supply more than confirmatory evidence of climatic differences already known by other means. [ 1 ]

Climatic Change 5 (1983) 85-93. 0165-0009/83/0051-0085501.35. Copyright �9 1983 by D. Reidel Publishing Co., Dordrecht, Holland, and Boston, U.S.A.

86 Timothy Ball

Similarly,

� 9 but it seems unlikely that any systematic me thod for deriving past distr ibutions of global climate f rom bird evidence alone could be worked out. [2]

This article has no intention of disputing this particular point of view. Nonetheless there is an aspect of the life pattern of some birds that could provide useful information

about climate and climatic changes. In order to find better environments for the different activities in their life cycle birds migrate from one region to another. These migrations are a practice of many species of birds and tend to be precipitated by changes in the seasons.

It would seem logical then that if these were changes in the onset of these seasons there would be similar changes in the dates on which the migrations occurred�9 The Hudson's

Bay Company documents provide the information on the date of arrival of the geese in their spring movements northward to nesting grounds in the Hudson Bay region of

northern North America. The same documents also served as the source of daffy climatic information from which the wind data was calculated for the period from 1715 A.D. to 1825 A.D. The article will attempt to show that a comparison of the date of arrival of

the geese at York Factory and Churchill in the Province of Manitoba can be related to the percentage of southerly winds recorded at those locations.

Research into the climatic factors that cause or affect bird migration have been extensive and detailed. Bagg et al. (1950) examined the relationship between barometric pressure and the spring migration, while others (e.g., Raynor, 1956; Lack, 1960; Richard-

son, 1966; Nisbet and Drury, 1968; Curtis, 1969; Able, 1973) all attempted to relate

either specific weather variables to migration or the effect of weather in specific regions.

A study in the latter category was carried out by Blokpoel and Gauthier on the influence of weather on the irdgration of Lesser Snow and Blue Geese across Manitoba in Central

Canada. [3]

Not surprisingly it was found that weather conditions at the point of destination had

no affect on the migration�9

The first migrants arrived at Kinoje between 1 0 - 1 3 in each year regardless o f large differences in pre- vailing temperatures and snow conditions�9 The first major migrations, however, were correlated with weather. In 1968 and 1969, geese arrived in numbers when some of the muskeg was snowfree . . . The major arrival in 1967 was the latest (28 April), when the habi tat was still ice-bound and the delay to peak nest initiation was 16 days. Thus, migrations were no t dictated by weather and habitat condi- tions at the point of arrival at Kinoje. [41

If weather is a controlling factor it is not weather at the point of arrival but weather at some other stage of the journey. Subsequent investigation revealed that,

� 9 major migrations were correlated with south winds and warming c o n d i t i o n s . . , on some occasions, these geese migrated nons top for the final 1050 km (650 miles). [5]

It appears that the birds relate their migratory decisions primarily to one climatic variable, namely wind direction�9 The warming conditions would be expected with a south wind in these latitudes and are therefore not the controlling factor. At this time of year the north- ward seasonal migration of the Arctic Front and its accompanying cyclonic depressions result in weather variability that is only matched by the southward migration in the fall.

The Migration of Geese as an Indicator of Climate Change in the Southern Hudson Bay Region 8 7

Movement of these systems results in periods of southerly winds as they traverse from

west to east. A study carried out for the Associate Committee on Bird Hazards to Aircraft of the

National Research Council of Canada attempted to create a predictive model of geese

migrations in order to reduce the probability of collisions between birds and aircraft.

The results obtained were optimistic suggesting that major waves of migration can be

predicted with reasonable accuracy. In the conclusion it was found that,

The following five weather factors appeared most useful for predicting spring migration: direction of surface wind and precipitation at Pilot Mound, and direction of surface wind and of geostrophic wind and precipitation at Winnipeg. [6]

The implication is that the birds are an indication of the change in pressure patterns

commensurate with the onset of spring in central and northern latitudes. Aircraft crossing

the Atlantic in the pre-jet era would fly similar pressure pattern routes. In many cases it

was quicker to fly on the appropriate side of a cyclonic or anti-cyclonic pressure system

to obtain a tailwind, even if the actual distance flown was greater. The geese appear to use

similar methods, although more probably due to a lack of food enroute rather than the

need for speed.

Most species of migrant geese in North America return to their breeding grounds several weeks in advance of the spring breakup. Nest sites are sought out as soon as the thaw begins... [7]

A combination of these points suggests that the initial date of arrival of the geese can

serve as an indicator of the onset of spring weather patterns. Records of the date of

arrival of geese at one location over a long time should reflect changes in those patterns.

Hudson's Bay Company Records

Hudson's Bay Company posts located along the shores of Hudson Bay were established at

York Factory on the Nelson River in 1714 and at Churchill Factory on the Churchill

River in 1718 (see Figure 1). A requirement o f the company was that daily journals be

maintained which would include information relevant to the operation of the post.

Two of these entries recorded weather observations, and comments on food supply obtained by the company men or in trade with the indigenous population. The weather

data has been recorded as part of a larger computer study that will expand knowledge

of the climatic conditions of this remote region since 1715. The most consistent weather

variable recorded was the wind direction which was determined from the flag at the top

of a fifty foot mast in front of the factory. Normally one reading per day was recorded,

however if there was a change during the day this was recorded. It is this record which has

provided the wind direction data used in this study. The basic food supply for the Company posts during long winter months was salted

goose. They constituted the major ingredient of what was referred to as 'Country provi-

sions', as distinguished from English provisions. The objective was to be as self-sufficient

as possible, as English provisions were shipped from London at great expense and could

"60 1 0 2

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8 8 T i m o t h y Ball

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0 30 6 0 9 0 120 miles

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o 500 i J mi les

Fig. 1. L o c a t i o n o f S t u d y Sites .

The Migration of Geese as an lndicator of Climate Change in the Southern Hudson Bay Region 89

rapidly deplete profit margins. There was considerable pressure to limit the use of these

provisions and to obtain as much local food as possible. The Company encouraged the

planting of gardens to further this concept.

Preservation of food by freezing was unknown, therefore meat was either eaten when

obtained or, in the case of the geese, salted for later consumption. The salted goose was not a great delicacy and after a long hard winter a daily diet must have been monotonous. However Factory was aware of the importance of the goose hunt and early development

of the hunters was a very important matter. Some Indians remained at the posts specif- ically for the hunt, while others came in from surrounding areas. They, along with some of the Company's men were sent to the goose hunting areas well in advance of the expected

date of arrival. The early deployment indicates the importance of the hunt and total kills were reli-

giously recorded. Similarly the first sighting of the season is recorded and provides the

second element of this study.

Figure 2 is a plot of the date of first sighting of geese at York Factory and Churchill for the period from 1715 to 1825. The date of sighting was obtained by recording from

the daily journals the date on which it was noted that geese were sighted. In some years a single goose was noted as having been observed but this was not considered to be sig-

nificant, therefore only the plural form indicating the arrival of several geese is indicated

in the graph. Figure 3 shows the percentage of south winds recorded at the two sites for the period

from the 15th of April to the 30th of May for the same years that geese observations

were made. These dates were selected because they cover the period of time that the

geese would have been in transit in their northward migration. It should be noted that

25-

20-

15-

~lO-

q -

J 1 - 3 0 -

2 5 -

2 O -

1 5 -

~, " 1 7 , - - " -

r '

' "i J i

i 0 . . . . i . . . . i . . . . i . . . . f . . . . , . . . . , . . . . i . . . . i . . . . , . . . . i . . . . r . . . . i .

- - Church i l l

. . . . . York Fac to ry

Fig. 2. Date of first sighting of geese at York Factory and Churchill.

90 Timothy Ball

40-1

35~t

3o4 !

~ , ~ 20 : ; i :;

I A ~ :: ?, ,:i II

t A/./,.:i^al t .... ! , - , , s t / - - , , ,

1715 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 1800 05 10 15 20 25

- - Church i l l

. . . . . Y o r k Fac to ry

Fig. 3. Percentage of south wind at York Factory and Churchill.

only south winds were included, however it is possible that an even better correlation

between date of arrival and percentage of tail winds might have been achieved if all southerly component winds had been used. At the present time this data is unavailable.

The date of arrival curves in Figure 2 and the percentage of south winds curves in

Figure 3, show correlation between the data and suggest an homogeneity between the

two posts. This suggests consistency in the observations and tends to validate the data. Support for this point is found in the written record. At York Factory in 1778 the geese did not arrive until June 1st, the latest date in the record. Samuel Hearne writes in the Churchill journal for the same year, "Goose killed latest ever known at this place". [8]

Despite gaps in the record some trends in the date of arrival are apparent. (1) There is a gradual change to later date between 1715 and 1745.

(2) The date is relatively stable from 1745 to 1770.

(3) There is a slight shift to an earlier date from 1770 to 1810. (4) Although incomplete a change to a later date is apparent from 1810 to 1825.

(5) Except for the period from 1745 to 1770 the graph shows great variability. Apart from these trends there is visual evidence that in some of the years with an early

arrival date there is a higher than average percentage of south winds. Statisticalverification

of this correlation was determined by the use of a phi coefficient. This test was chosen as it is a measure of the correlation of attributes because the categories into which the observations of geese arrivals and percentage frequencies of southerly winds may be considered as attributes of the observations, and therefore reveal information about the strength of the association between the two variables. Further the significance of the

association can be measured by a chi square test. The phi (~) coefficient requires a 2 x 2 contingency table which was created by

comparing the date of arrival against the percentage of southerly winds. At York Factory 85 yr of observation were available and 90 at Churchill Factory. The date of arrival was given a numerical value measured from a base of 1 assigned to the 1st of April. For example the 5th of May would be number 35. The average date of arrival was calculated

The Migration of Geese as an Indicator of Climate Change in the Southern Hudson Bay Region 91

from these figures to be 38 at Churchill and 35 at York.

The contingency table posed the following questions:

(a) Early arrival of geese/late arrival of geese.

(b) Above average percentage of southerly winds/below average percentage of south-

erly winds.

Early arrival Late arrival of geese geese

Above average percentage of southerly wind

A B A + B

Below average percentage of C D C + D

A + C B + D To tal

The phi coefficient is calculated as follows

AD - BC = (1)

~/(A + B)(C + D)(A + C)(B + D)

The sign for 4) is determined by the cross products in the numerator; if AD > BC ~ is

positive, AD ( BC ck is negative.

At York Factory the contingency table is:

Early Late

Above 36 13 49 Below 12 24 36

48 37 85

Substituting in (1),

~b = ( 3 6 x 2 4 ) - ( 1 3 x 12)

x/ (49)(36)(48)(37)

864 - 156 -

X/3 132 864

708 4 -

1770

r = 0.400.

92 Timothy Ball

The phi value of 0.400 indicates a moderately strong positive association. Checking

this value for significance we have;

• = (0.400)2 x 85 = 13.6.

This exceeds the critical value of 10.83 for X 2 0.001 with 1 deg of freedom indicating a

high level of significance.

At Churchill Factory the contingency table is as follows:

Early Late

Above 30 16 46 Below 11 33 44

41 49 90

= ( 3 0 - 3 3 ) - ( 1 6 x 1 1 )

~/(46)(44)(41)(49)

990 - 176

~/4 066 216

814 2016

= O.4O4.

The phi value of 0.404 indicates a moderately strong positive association. For • o.ool

with 1 deg of freedom the critical value is 10.83. The calculated X 2 value at Churchill is;

X 2 = (0.404) 2 x 90 = 14.68

again indicating a high level of significance.

At the present time there is insufficient data available in this region over the period

of time under study to establish whether or not the variations are consistent with other

variations in climatic variables and indicators. The high degree of statistical correlation

between the early arrival and the percentage of southerly winds suggests that the records

maintained by the Hudson's Bay Company are reliable sources of climatic data. It also

lends support to the studies that claim a tailwind component is an important element

for determining the date of migration. Variations in the percentage frequency of south

winds appears to indicate variations in the onset of spring and therefore early northward

movement of the Arctic front. These variations might also be indicators of the shifts

from zonal to meridional flow in the westerlies. This paper has only examined two sites on Hudson Bay but the Hudson's Bay Company

had an extensive network of posts both around the Bay, and commencing in 1794, in the interior of North America. At most of these posts the goose hunt was an extremely important part of the constant need for country provisions, hopefully records main-

The Migration of Geese as an Indicator of Climate Change in the Southern Hudson Bay Region 93

rained at these posts will cor robora te and ex tend our knowledge o f cl imatic variabil i ty

in recent historic t imes.

(Received October 20, 1981; in revised form May 3, 1982)

References

[1 ] Lamb, H. H.: 1977, Climate; Present, Past and Future, London, Methuen, p. 234. [2] lbid.,p. 235. [3] Blokpoel, H.: 1975, Migration of Lesser Snow and Blue Geese in spring across southern Manitoba,

Part 1, 'Distribution, Chronology, Directions, Numbers, Heights and Speeds', Ottawa, Canadian Wildlife Service, Report Series Number 28, p. 40.

[4] lbid.,p. 14. [5] Ibid.,p. 15. [6] Blokpoel, H. and Gauthier, Maureen: 1975, Migration of Lesser Snow and Blue Geese in spring

across southern Manitoba, Part 2. 'Influence of the Weather and Prediction of Major Flights', Ottawa, Canadian Wildlife Service, Report Series Number 32, p. 24.

[71 Hanson, Harold C.: 1965, The Giant Canada Goose, Carbondale and Edwardsville: Southern Illinois University Press, p. 89.

[81 Hudson's Bay Company Archives: Daily Journals Catalogue Number B42/a/97, p. 16.

Other References

Able, K. P.: 1973, 'The Role of Weather Variables and Flight Direction in Determining the Magnitude of Nocturnal Bird Migration', Ecology 54, 1031-1041.

Bagg, A. M., Gunn, W. W., Miller, D. S., Nichols, J. T., Smith,W.,and Wolfarth,F.P.: 1950, 'Barometric Pressure-Patterns and Spring Bird Migration', Wilson Bull. 62, 5-19 .

Curtis, S. G.: 1969, 'Spring Migration and Weather at Madison, Wisconsin', Wilson Bull. 81,235-245. Lack, D.: 1960, q'he Influence of Weather on Passerine Migration', A review. Auk. 77, 171-209. Nisbet, I. C. T. and Drury, W. H. Jr.: 1968, 'Short-Term Effects of Weather on Bird Migration: A Field

Study Using Multivariate Statistics',Animal Behaviour 16,496-530. Raynor, G. S.: 1956, 'Meteorological Variables and the Northward Movement of Nocturnal Land Bird

Migrants',Auk. 73,153-175. Richardson, W. J.: 1966, 'Weather and Late Spring Migration of Birds into Southern Ontario', Wilson

Bull. 78,400-414.