Seasonal occurrences and abundances of six common migratory waders in Botany Bay, 1942-1966, a documentation and analysis of Arnold McGill's long-term data set

5 Pages·1995·2.2 MB·English

by  Allen Keast

Seasonal occurrences and abundances of six common migratory
waders in Botany Bay, 1942-1966, a documentation and
analysis of Arnold McGill's long-term data set
Allen Keast
Department of Biology, Queen's University, Kingston, Ontario, K7L 3N6, Canada
ABSTRACT
Times of occurrence and abundances of five Palearctic, and one New Zealand, migratory waders
in Botany Bay over the period 1942 to 1966, are documented from Arnold McGill's unique data set.
The Sharp-tailed Sandpiper occurred from early September to the end of February; Red-necked Stint
from beginning of September to early March; Bar-tailed Godwit from September to April; Golden
Plover, October-April; and Double-banded Plover from late March to late August. Taking into account
birds on passage the sandpiper was most abundant in the first years, the stint from 1952 to 1959;
godwit from 1952 to 1959: curlew sandpiper from 1957 to 1966; numbers of the two plover species
were relatively constant. It is suggested that the variation reflects level of success on the breeding
grounds, not changes in the quality of the Botany Bay habitat since degradational changes In the latter
had not then occurred. The study emphasizes the great importance of Botany Bay as a wader habitat;
it is still a good place to "see" waders but only future quantitative munts will show its current status.
Data on quality of the feeding habitat, in addition to dlanges in area, is needed. Future wader conserva-
tion necessitates a simultaneous study of aN major feeding grounds for waders along the east mast.
INTRODUCTION and shape of the bill, it was possible to identify
these otherwise similar-looking birds. It was
Botany Bay and, especially the wide sand-
Keith Hindwood who introduced Arnold and
flats at the northern end between Cooks River
1 to the Botany Bay flats. The earlier trips
and La Perouse, have long been recognized as
were multi-person affairs with Keith
one of the most important feeding areas on
Hindwood, Arnold and myself, Ernie Hoskin,
the New South Wales coast for migratory
and others taking part. I was a regular
waders. The width of the flats exposed at low
companion of Arnold for his first couple of
tide was about 400 m, and their length in
years. Several of Arnold's trips each year
excess of a kilometre. They were visibly rich
would be with Keith Hindwood after that and,
in invertebrate life, with a small green
jointly, they worked out the identities of some
oligochaete having a density of up to 10 per
of the rarer and more difficult species. Arnold
square metre (pers. obs.).
was ultimately to become perhaps Australia's
From the 1940s onwards the waders of the most knowledgeable wader expert. Early
flats were the focus of attention by Sydney papers by the Sydney "wader group" included
ornithologists. Arnold McGill was pre-eminent Hindwood (1942), McGill (1943, 1947), and
in the studies and from 1942 to 1965 made McGill and Keast (1945)
some 200 surveys, alone or with Keith
Hindwood, Ernie Hoskins, and myself. It is
METHODS
important that the results of these surveys be
put on permanent record and here I take The flats would be visited just as the tide
Arnold McGill's field lists and incorporate
was running out so that maximum time would
some additional data by myself and others.
be spent with the birds as they fed. The counts
Making the data available is important in that
would start from immediately adjacent to the
the area has been severely impinged upon by
Cooks River mouth. Walking slowly eastwards
airport and shipping container port develop-
we would identify and count each group of
ment. It provides a basis relative to which
waders. As the waders flushed the direction of
modern counts can be assessed.
flight would be noted so as not to count the
Interest in migratory waders in the Sydney same flocks twice. A kilometre would be so
ornithological community surged in the late covered and then the remaining stretch of
1930s when Serventy (1938) showed how, by sand explored long-distance by field-glasses to
studying the distribution of white on the tail confirm proportions of species and make the
and on the wing, colour of the legs, and length count as complete as possible.
34 Australian Zoologisf, Vol. 30(1)
The greatest number of visits were made SHARP-TAILED SANDPIPER - Botany Bay
in 1942 and 1943. with 13 and 15 visits
700
respectively by Arnold or Arnold jointly with 600 1942- 43
500
others of us, and six and sevena dditional visits No. lrips = 56
400
by myself. During the 1944-1945 wartime 300
years with severe petrol rationing Arnold was 210000 .l-t.-. rlrhll.,.
only able to make a few visits to the flats. From 0
o 700
1947 onwards the number of visits a year to l 600
E:>500
the flats was 15-20, 75-80% of them being by E 400
Arnold or with Arnold as a member of the = 300
200
group. In any year three-quarters would be 100 '*''i'_.1
made during the August-April period when E= 3000 il
the northern migrants were passing through z 200. *=oo
on passageo r summering in the Bay, with the 1000.. -h tr -
remainder being directed at the Double- 210000.. 1957-59 N=s8
banded Dotterel or Plover Charad,riusb icinctus. -.r.ll I l. .lt I .h
200.
a winter visitor from New Zealand. 100.
Because the visits were rather scattered in
JUL AUG SEPTO CTNOVDECJ AN FEB MAH APR MAY
time I have consolidated the data into series
Date
of two (1942-1943) and three (other years)
averages. In doing so, if a single seven-day
period was only visited once during the two or RED-NECKEDS TINT- Botany Bay
three years, its counts stand, if twice or more '*
an average for the particular period is struck. cord I
300
This objective is both to give the most accurate .:" l.r-h| . .,r,i,,,="
200
average picture of arrival and departure 100
(including "passage"d ates),a nd bestb ring out 0
any longer-term shifts in abundance. In the 200 1946-48 N=34
100 | .r I hrrl ll --.-,
latter obviously the summer data is more q 0
G
valid, it representing the period of stability: at 1952- 54
migration times numbers fluctuate greatly as il, l,hil l
flocks arrive and depart. In the graphs, data
from 1942 and 1943 (when most trips were
E
made) is grouped, as is that from 1946 to zl
1948, 1952t o 1954, 1957t o 1959,a nd 1964 .r i,;i;, .li,ll ,|hril,rt,l, ,
to 1966.T oo few trips were made in the other
years for the data to warrant inclusion.
Data is given only for the six common "ffi1,,1,,.,1',l,rll,l
species: Sharp-tailed Sandpiper Erolia -t. -,.,,-l="
acuminata, Red-necked Stint E. rufcollis, Bar-
tailed Godwit Lirnosal apponica,G olden Plover
JULY AUG SEP OCT NOVD ECJ AN FEB IVIARA PR MAY
Pluaialis fulua, Curlew Sandpiper Calid,ris
Date
fenuginea, and the Double-banded Dotterel.
Fzg. 1. Seasonal occurrences and abundances, Sharp-tailed
RESULTS Sandpiper and Red-necked Stint, Botany Bay mud-
flats, five clusters of years from 1942 to 1966.
Seasonal occurrences and abundances of
the various speciesw ere as follows:
Sharpaailed Sandpiper: Typically this species in small numbers of 50 to 100. Large numbers
arrived in the first week of September, with a appeared again in January: possibly represent-
major influx occurring in the second week. ing birds from further south, or in response
Then there tended to be a numerical drop, to improved resources. Usually the bulk
and a second peak in early October. In contrast disappeared by the end of February, but in
to the others this species did not exclusively some years small numbers lingered on into
utilize the flats; a more favoured summering March, and even early April. None were ever
habitat was saltmarsh and muddy creeks recorded between April and early August.
entering the bay (writer's data). From late Presumably the late August birds recorded in
October until early January flocks of birds 1942-1943 represented early returnees, and
were continuously present on the flats but not over-wintering birds.
Decembe1r9 95 Australian Zoologist, Vol. 30(1) 35
It is difficult to draw any conclusions about BAR- TAILEDG ODWIT- Botany Bay
long-term population changes from this data 'l1-::l"j
although far more birds *ere recorded on "]'*"' | . te42-43 No.riP=ss 6
,.l.lllll.rl r,,,-.rr-.r I rrr
northward passagei n 1942-1948 than sub-
sequently.
1946-48
N=34
r _l l. r - -.1-..-.-
Red,-nechcSd# n/; This was throughout a rather
more abundant species, occuriing in larger t00
flocks. There was commonly a Jma[ over- ,,ll,ilflLrfrlhl',lirli ,,,'l,,,rrrl
wintering nucleus of birds, usually less than q
50 birds. The major influx of migranrs from
't
ethaer lyn,oSrethp toecmcbuerrl.e dS autb tsheeq eunedn tolyf yAeuagiu-tsot- yaenadr Ict _ ovffibrlng
',,''-
abundances varied, but there wai commonlv o N=58
another_ peak in October. High number's E
occurred all summer: thus the flats represented zf r,;,,| lh||,ilfllu,t illlllltrLlrrl,r,,,
major habitat. I never found them in the salt 50
marshes. Return migration was initiated in
late February--early March. It was g-radual; 'll
small numbers remained into April. 50 t' ,l',.I lNt=6l12l,.,, .
lllltu r trh- .r.-,, ,
The.overview projected by the graphs is of 0
a significant population increasd in lgb2_ AUG SEP OCT NOV DEC JAN FEB MAB APR MAY
1959 relative ro earlier years, with numbers
Date
averaging smaller during the l964-1966
period. GOLDENP LOVER- BotanyB ay
Bar-tailed,G odwit: There was regularly an over- 6800 1942 - 4g ' indi@t6s ho r*ord ll No.r ips = so
wintering nucleus in this speciEs.p eak return 4200 ..r.--..I t,l.lll.llul r
migration occurred in September. The flats '.. "="
were a majoq summer feeding area, with the . l. r.l, ht,nli,lll. l
drop in numbers occurring in April.
@
G
Long-term variations in numbers occurred. pf, 11446000
Abundances in 1957-1959 were very high, oc 11220000
those of 1952 to 1954 less so; numbers were 60 1952-54
small from 1942 ro 1948 and in 1964 to 1966. o 40 .l.rr. ,rillll,ll ll,
E 20
The differences are real. The increase in zf 80
numbers from 1952 ro lgbg presumably 1es57e' I N=sa
40
indicates high success on thi breeding 20. ,ll .lrr.llll r --l.r
grounds. 0.
1964-66 *="
-t--, r-r.r llrrr ll -ilh
Gold,enP loaer: The year-to-year abundances
varied with numbers of birds usually being JUL AUG SEP OCT NOV DEC JAN FEB MAR APB MAY
small. The annual influx occurred in October] Date
JFleebreru awrya.s pao rpeuglualtaiorlny, owccituhr rinig bNuoivldeumpb eri-n Fig. 2.G Sodeawsito naanl do Gccoulrdreenn cpelso vaenr,d Baobtaunnyd aBnacey,s ,1 9B4a2r__1ta9il6e6d.
numbers in the latter month, and u peik i.,
March be.fore department in March--April.
Characteristically no birds over-winteied.
residents all summer. There was a clearcut
From time to time I found Golden plover
feeding flocks on the grassed Barton park numerical drop at the end of January, but in
some years they remained during February
fpreormio d-st haen dF t1hye,r eb w.rat st nhoe yp aottnelryn sint aiyheedir btirmieef aMnadr,c _he. sNpeoc imalelyimn btehres 1o9f 6t4h-i1s9 6sp6e-pceieriso odv, eirn-
of appearance. Populations in the area were wintered.
relatively constant bver the 20-year period.
During 19-42.-1943r he Curlew Sandpiper
lurlew Sandpiper: This species was recorded occurred only in modest numbers but there-
in August but there was a striking influx of after was an abundant summer species.
migrants aj t!t" end of Septeirber--early Highest numbers occurred in the^ later
October. The birds were abundant feeding years.
36 AustraliaZno ologistV, ot.3 0(t)
December 1995
CURLEWS ANDPIPER- BotanY BaY Double-bandedD otterel (Ploaer): This species
arrived at the end of March and tended
150
1942-43 I .ind€tsrcre@rd to remain in good numbers until late May.
100
No. rrips - 56 Thereafter there was a drop in numbers, with
the time of this varying, followed by high
200 numbers from late June to the end of
1945- 48 August. Presumably there was some seasonal
|lr,.,l. .l ,l, N=34 adjustment during the stay in response to
resources.
lrL|
Numbers were relatively uniform from
N=44
1942t o 1966.
| , l,,l',h., ,
-.1l,- t.
DISCUSSION
o
150 The arrival and departure times of the six
t00 rrilil1r.i.l,.1.N=5,8 , speciesa re fairly constant but showed year to
year variation by a couple of weeks.T his could
0 partly be an artifact of the way the data was
150
100 1964- 66 l,lrf|i|i|li,,l'r,, N,=62 collected. However, in all cases there was
obviously a spread in times, i.e., in the arrival
50
I-rr I and departure of flocks. Numbers of birds
were highest at times of passage.T he major
JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY
status of Botany Bay as a residence area for
Date waders is amply confirmed. Small numbers of
stints and godwits overwintered and did not
return north to breed.
DOUBLE- BANDEDD OTTEREL- Botany Bay Duration of stay in the bay varied with the
species;S eptember-Februaryw ith the Sharp-
tailed Sandpiper; Curlew Sandpiper, October-
No. lrips = 48
1942-4 3 Februarv. The stav of six and five months in
these speciesw as eclipsedb y the eight to nine
months of the Bar-tailed Godwit. The stayw as
,.,rlr.,l,l ,ll l
I
five months with the Double-banded Plover.
which was present at the opposite time of the
year to the other species.
o 1946- 48 hlN=2l4 The mid-seasonc ounts can be used to assess
E
changes in abundance. The Sharp-tailed
pf 30 1.,1. l,h
Sandpiper (though numbers on northward
E passages howed a drop after the first years),
.c Golden Plover, and Double-banded Plover,
o '=" maintained fairly constant populations
Lq) res2-s4 I throughout the period. Increasesi n numbers
-o tl
E of Red-necked Stints and Bar-tailed Godwits
=
z | -,-,tlll,ll-l.l.h. over the 1952-1959 period are indicated; and
the Curlew Sandpiper numbers increased in
50 tl the final years.
- ll
40 1957- 59 "=*
30 lrrrrlllrlll,'1, Because flocks may pass through quickly,
more regular counts than those made here
0
would be necessaryt o assessn umbers of birds
0 66
on passage.I t would be valuable to know how
1964-
20 .lhl h..llhhru-="long migrating flocks stay in the Bay. It is
10
likely that southward moving flocks stay
JAN FEB MAR APRM AYJ UN JULA UG SEP longer than the reverse, as is the case with
passerines in the Northern Hemisphere,
Date associatedw ith the need to establishb reeding
territories. Doubtless many flocks over-flew
Fig. 3. Seasonal occurrences and abundances, Curlew Botany Bay and would not be included in the
Sandpiper and Double-banded Dotterel, Botany Bay,
1942-1966. counts.
Decembe1r 995 AustralianZ oologist, VoL 30(1) 37
Differences in numbers of birds summering one or two areas might not matter; progressive
in the Bay over the 20-year period reflects, degradation of feeding places throughout
I suspect, varying reproductive successes on would be serious.
the breeding grounds rather than conditions
Botany Bay, the prime wader area, like the
in Australia. Unfortunately no data was
Hunter, continues to be under intense develop-
gathered on year-to-year variation in the prey
mental pressure. It would be interesting to
resource base in Australia: resolution of the
know the extent to which the extension of the
matter would require this.
Cooks River breakwater well out into the bay,
and interruption to the inlet flow from the
BOTANY BAY AS A PRESENT
Eastlakes Ponds, has affected nutrient loading
AND FUTURE WADER HABITAT
at the north end of the Bay. Has the over-use
The present data set, as a basis for making of natural resources (over-harvesting of
comparisons with contemporary numbers of prawns and fish) indirectly affected wader
waders, should be used with caution. The area habitat? There is a need for quantitative
covered in the surveys was not precisely studies at all levels.
measured: indeed it would have been difficult
The Bay remains a "good area to see
to do better because the flocks ranged widely.
waders and, recently at the south end, I saw
This was, however, taken into consideration
good populations of godwits, sandpipers,
throughout the surveys and the count-area
plovers, and tattlers. Some remain along the
kept sufficiently large to accommodate this.
north shore. It is hoped that a contract let
Unfortunately, the feeding wader popula-
recently to study current wader populations
tions at the southern end of Botany Bay,
will reveal something of current over-all
e.g., in Quibrey and Yowie Bays, were not
wader status in the Bay. Ultimately, of course,
simultaneously monitored: we had all we
total surveys of the entire east coast habitat
could handle with the high numbers at the
and abundances is critical.
northern end. This would make it impossible
to compare total Botany Bay wader popula-
tions then and now. It would be worth while ACKNOWLEDGEMENT
developing numbers as a ratio of available
This article was written whilst the writer held
feeding area in 1940 with that of today. The
a Canadian National Science and Engineering
smaller area of feeding habitat now remaining
Research Council Grant: the costs of develop-
could, however, represent the "best" or
ing the diagrams is from that source. I should
"worst" section of the old habitat: what is left
like to thank this body.
could, alternatively, have become secondarily
nutritionally enriched or have become a
"desert". REFERENCES
Obviously the health of our migratory wader Hindwood, K. A, 1942. The birds of Long Reef, New South
populations cannot be assessed just in terms Wales. Proc. Zool. Soc. NSW 1942: 1633.
of Botany Bay studies. Southward moving
McGill, A. R., 1943. Bird movements in rhe Lower Cooks
waders have a series of potential feeding areas River District. Emu 42: 174.
available to them, separated by long gaps:
McGill. A. R.. 1947. Unra\,elline the Knots. Notes on the
sections of Cape York, the Cairns waterfront, occurrence of the genus Caidris in Australia. Emu 47:
Moreton Bay, the Hunter, Botany Bay, and 137-46.
Lake Illawarra. Presumably they will linger in
McGill, A. R. and Keast, A., 1945. The Mongolian Sand-
any one area proportionately to their immediate dotterel in Australia. Emu 45: 202-16.
nutritional needs and to the quality and
Serventy, D. L., 1938 A guide to the identification of the
amount of food available. Presumably loss of waders. Emu 38: 65-76.
38 Australian Zoologisf, Vo1. 30(1)