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Subfossil avian deposits fromPoukawa, Hawkes Bay, and the firstrecord of Oxyura australis (Blue-billed Duck) from New ZealandPeter L. Horn aa Zoology Department , University of Canterbury ,Christchurch, New ZealandPublished online: 21 Dec 2011.

To cite this article: Peter L. Horn (1983) Subfossil avian deposits from Poukawa, Hawkes Bay,and the first record of Oxyura australis (Blue-billed Duck) from New Zealand, Journal of theRoyal Society of New Zealand, 13:1-2, 67-78, DOI: 10.1080/03036758.1983.10415338

To link to this article: http://dx.doi.org/10.1080/03036758.1983.10415338

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© Journal of the Royal Society of New Zealand, Volume 13, Number 112, 1983, pp. 67-78

Subfossil avian deposits from Poukawa, Hawkes Bay, and the first record of Oxyura australis (Blue-billed Duck) from New Zeal2nd

Peter L. Horn-

An assemblage of subfossil avian remains deposited over a period of 7 ,000 years at Poukawa, Hawkes Bay, is examined. The abundance of many of the larger bird taxa (Apteryx, Cygnus, Notomis, Circus, Strigops) appears to have declined over the whole period, and they were all rare by 1,000 years ago. The considerable changes in bird community composition at Poukawa during the last 1,000 years, including the extinction of many species, probably resulted from forest modification caused by fires lit by Polynesian man. Differences in the occurrence of various skeletal elements of the birds are apparent, and possible reasons for this are discussed. The first New Zealand record of Oxyura australis Gould, 1836 (Blue­billed Duck) is reported.

INTRODUCTION Lake Poukawa (21 m a.s.l.) lies some 25 km southwest of Hastings, near the southern

end of a valley bordered by two low limestone ranges. The lake is surrounded by extensive peat swamps, and several archaeological sites are adjacent to it. Systematic excavations about 2 km northeast of the lake at Sites N14111 and N14112 (N.Z. Archaeological Association site numbers; N1411154053) have yielded considerable numbers of avian bones, land and freshwater molluscs, seeds and wood (Price, 1963, 1965). Notable finds from these sites have been the holotype skeleton of Pelecanus novaezealandiae, the New Zealand Pelican (Scarlett, 1966; Rich & van Tets, 1981), and bones of Biziura delautouri, the Musk Duck (Scarlett, 1969; Olson, 1977). A large natural deposit of subfossil avian remains was recovered from the Te Aute swamp, about 7 km to the south of Lake Poukawa (Hamilton, 1899).

This study deals with the subfossil avian remains recovered by Mr T. R. Price and several helpers over the period 1966 to 1975 from Site N141112 (N141/140050) about one kilometre northeast of Lake Poukawa. The author assisted with excavations in 1973, 1974 and 1975.

The site is on a ridge rising about two metres above the surrounding ground level of the drained swamp. A generalised cross-section of one side of the ridge (Fig. 1) shows the presence of a number of tephras, the most easily discernible and distinctive being the Taupo Pumice (1,851 ± 17 yearsB.P.) and the WaimihiaLapilli (3,472 ± 70 years B.P.) (Pullar, 1970). Two unidentified tephras were found below the Waimihia Lapilli, and from descriptions in Howorth et al. (1980) I consider that they may be the Whakatane Ash (about 5000 years B.P., also tentatively identified as such by W. A. Pullar, Soil Bureau, DSIR) and the Hinemaiaia Ash (about 6,000 years B.P.).

METHODS An area of approximately 3,500 m 2 was excavated layer by layer, and the position

in the stratigraphy of all bones was noted at the time of recovery. All unbroken bones, and many bone fragments, were later identified to species. For the purposes of this study,

• Zoology Department, University of Canterbury, Christchurch, New Zealand.

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o ...J 1 2 3

~:== __ ~

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,...oc>"

~: ,,-~(:>IO H

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&

L::

j L

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ed

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Fig

. l-

Gen

eral

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ss-s

ecti

on o

f one

sid

e o

f the

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ge w

hich

com

pris

es S

ite

N14

1/12

. T

=

Tau

po

Pum

ice,

Wa

= W

aim

ihia

Lap

illi

, Wh

= ?

Wha

kata

ne

Ash

, H

=

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inem

aiai

a A

sh.

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Horn - Subfossil avian deposits, Poukawa 69

the site was divided into three layers as shown in Fig. 1. It was hoped that comparison of the recovered avifaunal remains from three broad time-zones would suggest changes that occurred in the avian communities. Bones from Layer 3 (formed between about 7,000 and 4,000 years B. P.) were situated either more than 5 cm below the Waimihia Lapilli or in the mixed peat and lake sediment that was more than 10 cm below the Taupo Pumice. Bones from Layer 2 (formed between about 4,000 and 1,000 years B.P.) comprised all those found below the Taupo Pumice but not in Layer 3, and those less than 7 cm above the Taupo Pumice. All remaining bones were classified from Layer 1 which was formed during the last 1,000 years, the generally accepted duration of human occupation in New Zealand (Moore and Tiller, 1975). Some of the Layer 1 bones were recovered from shell middens which McFadgen (1979) suggested were less than 300 years old. From personal observations, I consider that less than a fifth of the Layer 1 material originated from this source.

Parts of Site N141/12 have been disturbed by European agriculture (McFadgen, 1979), but this mixing would be confined to Layer lover most of the site. However, along some of the ridge top where Layer 1 is less than 15 cm thick, some mixing between Layers 1 and 2 has occurred and the Taupo Pumice band has been disturbed.

The ridge on which site N141/12 was situated has been an island on many occasions since the initial formation of the lake; bands of diatomaceous earth in the stratigraphy indicated the occurrence of high water levels, particularly from about 2,000 to 4,000 years B.P. (author's unpublished data). Accessibility of the site to flightless birds, therefore, would have been restricted at times, although they may have been abundant contemporaneously in other areas of the valley. Forest-birds may also have been locally abundant, but scarce on the site, because the environment of the ridge may not have provided optimal nesting or foraging areas. High lake levels may have resulted in the beaching of numerous water-bird carcasses near the base of the ridge, thereby enhancing the numbers of recovered bones from this group. Therefore, the bones from Site N141112 probably give an accurate representation of the relative abundance of species within each of the three major groups of birds, but comparisons. of abundance between species from different groups may not be valid.

A brief reconstruction of the geographical characteristics of the Poukawa basin over the past 8,000 years (Dr M. S. McGlone, peTS. comm., March 1982) suggested that the peat deposition began between 8,000 and 7,500 years ago. Matai (Podocarpus spicatus) forest became established on the surrounding hills (with the many associated species typical of such forest), while the entire basin was occupied by white pine (Dacrycarpus dacrydioides) forest with some scrub and swamp. About 5,000 years ago the lake began to form, and it has been there ever since, although there have been numerous fluctuations in its size. The replacement of po do carp forest by bracken and scrub began about 1,000 years ago, and evidence of forest burning since this time has been put forward (McGlone, 1978).

RESULTS Numerous moa remains were found on Site N141112, particularly in Layers 2 and

3 (mainly unidentifiable fragments, but often of Pachyornis mappini and also Euryapteryx and Dinornis species). They have not been included in this analysis because correct identification of much of the material was not possible.

Data have been tabulated for four bird communities separately (water-birds excluding sea-birds, ground-dwelling birds, forest-dwelling birds, and seabirds: Tables 1-4) so that temporal changes in the absolute and relative abundance of species in each habitat may be compared.

Water-birds Four rare species of Anatidae were recorded from Site N141112. Bones of a Musk Duck, Biziura sp., had previously been found at three localities in

New Zealand, including Site N141/1 (Scarlett, 1969), and were assumed to be of the living Australian species, B. lobata. Three more Biziura bones were identified from Layers

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Lay

er 1

M

NI

TN

B P

WC

P

TS

Pod

icep

s cr

ista

tus

(Cre

sted

Gre

be)

1 1

0.21

0.

17

Pod

icep

s ru

fope

ctus

(D

abch

ick)

8

27

1.71

1.

33

Pha

lacr

ocor

ax c

arbo

(B

lack

Sha

g)

71

968

15.1

7 11

. 78

Pha

lacr

ocor

ax v

ariu

s (P

ied

Sha

g)

Pha

lacr

ocor

ax m

elan

oleu

cos

(Lit

tle

Sha

g)

4 19

0.

85

0.66

A

rdea

pac

ific

a (W

hite

-nec

ked

Her

on

) E

gret

ta a

lba

(Whi

te H

ero

n)

2 6

0.43

0.

33

Bot

auru

s st

ella

ris

(Aus

tral

asia

n B

itte

rn)

1 1

0.21

0.

17

Dup

etor

flav

icol

lis

(Bla

ck B

itte

rn)

1 1

0.21

0.

17

Cyg

nus

sum

nere

nsis

(E

xtin

ct S

wan

) 3

8 0.

64

0.50

C

ygnu

s at

ratu

s (B

lack

Sw

an)

4 27

0.

85

0.66

E

urya

nas

fins

chi

(Fin

sch'

s D

uck)

3

5 0.

64

0.50

T

ador

na v

arie

gata

(P

arad

ise

She

lduc

k)

1 4

0.21

0.

17

An

as

supe

rcili

osa

(Gre

y D

uck)

99

60

0 21

.16

16.4

5 A

na

s gi

bber

ifro

ns (

Gre

y T

eal)

95

5

76

20

.30

15

.78

A

na

s au

ckla

ndic

a ch

loro

tis (

Bro

wn

Tea

l)

106

51

32

2.6

61

7.6

0

An

as

auck

land

ica

sp.

inde

t.

An

as

rhyn

chot

is (

N .Z

. S

hove

ler)

3

18

0.64

0.

50

Ayt

hya

nova

esee

land

iae

(N. Z

. S

caup

) 18

10

0 3.

85

3.00

M

ergu

s au

stra

lis

(Auc

klan

d Is

. M

erga

nser

) B

iziu

ra d

elau

tour

i (M

usk

Duc

k)

Oxy

ura

aust

rali

s (B

lue-

bill

ed D

uck)

P

orph

yrio

por

phyr

io (

Puk

eko)

48

41

0 10

.26

7.97

46

8 3,

284

10

07

7.7

4

Lay

er 2

M

NI

TN

B P

WC

P

TS

3 16

0.

43

0.26

8

20

1.14

0.

68

5 16

0.

71

0.43

1

1 0.

14

0.08

7

16

1.00

0.

60

4 11

0.

57

0.34

7

15

1.00

0.

60

1 4

0.14

0.

08

16

186

2.28

1.

37

26

106

3.70

2.

22

6 19

0.

85

0.51

14

9 99

1 21

.23

12.7

1 15

2 7

22

21

.65

12.

97

190

70

92

7.0

81

6.2

1

1 1

0.14

0.

08

20

79

2.85

1.

71

94

301

13.3

9 8.

02

2 3

0.28

0

. .17

1 1

0.14

0.

08

7 16

1.

00

0.60

2

4 0.

28

0.17

70

2 3,

237

100

59.8

9

Lay

er 3

M

NI

TN

B P

WC

P

TS

2 4

0.45

0.

28

5 11

1.

11

0.70

3

9 0.

67

0.42

2

4 0.

45

0.28

5

14

1.11

0.

70

1 3

0.22

0.

14

3 14

0.

67

0.42

17

225

3.79

2.

37

17

53

3.79

2.

37

2 2

0.45

0.

28

107

664

23.8

2 14

.90

91

40

42

0.2

7 1

2.68

12

5 4

45

27

.83

17.

41

12

74

2.67

1.

67

53

196

11.8

0 7.

38

2 2

0.45

0.

28

2 4

0.45

0.

28

449

2,12

8 1

00

62

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--.:

)

o ::tl

~ ~

~

" ~.

q- ~

~

8; ~ ., ~ ~

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Horn - Subjossil avian deposits, Poukawa 71

2 and 3 during this study. Biziura bones are now recorded from four North Island and two South Island localities (Millener, 1981b). A comparison of the structure and measurements of these bones with specimens of B. lobata from Australia suggests that the New Zealand Biziura was about 10% larger and morphologically distinct from its Australian counterpart (Olson, 1977; Millener, 1981b), and that the name Biziura delautouri Forbes, 1892 should be retained.

Three bones of Mergus australis (Auckland Islands Merganser) (Kear and Scarlett, 1970) were found in Layer 2. They constitute only the third record of this species from the North Island, the other two localities being Motutapu Island (Davidson, 1978) and Tokerau Beach (Millener, 1981b). A small anatid ulna, also from Layer 2, remains unidentified. Dr G. F. van Tets (pers. comm., June 1981) considers that it belongs to the Anas aucklandica super-species complex, as he has seen some other bone material from New Zealand that suggests that there was a teal smaller than either A. aucklandica chlorotis (Brown Teal) or A. gibberiJrons gracilis (Grey Teal) on the main islands.

Bones of Oxyura australis (Blue-billed Duck) were also recovered from Layers 2 and 3. This is a living Australian species which has never before been recorded from New Zealand even though it appears to have been relatively abundant at Poukawa, particularly during the formation of Layer 2, where it comprised 1 % of the fresh-water community. Frith (1977) describes Oxyura as a completely aquatic species able to swim and dive expertly, but awkward and almost helpless on land. When alarmed they escape by diving, if in dense swamp, or flying if on open water. Oxyura are confined generally to ·densely vegetated, deep swamps, hence their absence from Layer 1 may be related to the presumed deforestation of the surrounding area during the last 1,000 years.

Five bones from Layers 1 and 2 may be those of Dupetor flavicollis (Black Bittern) and, if so, constitute the first record of this species from New Zealand (Horn, 1980). However, Dr P. R. Millener (pers. comm., October 1982) suggested that these bones could be of Ixobrychus novaezelandiae (Little Bittern).

Bones of Cygnus atratus (Black Swan), a species introduced to New Zealand before 1870 (Oliver, 1955), were recovered from Maori midden deposits.

The high abundance of Anas gibberiJrons (Grey Teal) (15.8, 13.0 and 12.7% in Layers 1,2 and 3 respectively) is unexpected, as this species was termed a "recent invader from Australia" by Williams (1964). It has occurred rarely in subfossil assemblages and is recorded from only seven North Island localities (Millener, 1981b).

Four species declined in relative abundance from Layer 3 upwards. Cygnus sumnerensis (Extinct Swan) declined by 42 % from Layer 3 to 2 and continued to decline in Layer 1; it was probably locally extinct by 700 years B.P. Sharp reductions in abundance during the last 1,000 years were recorded for three other members of the Anatidae. Anas rhynchotis (New Zealand Shoveler) and the extinct Euryanasfinschi (Finsch's Duck) were both reduced by 71 % and 77% respectively, compared with the period from 4,000 to 1,000 years B.P., while Aythya novaeseelandiae (New Zealand Scaup) suffered a reduction of 63%.

Two species, Phalacrocorax carbo (Black Shag) and Porphyrio porphyrio (Pukeko), increased in abundance to become the fourth and fifth largest components respectively of the freshwater community from Layer 1. Porphyrio, apparently self-introduced from Australia about 1,000 years ago, obviously thrived in the increasing areas of raupo that formed around the lake during this period (Fig. 2 of McGlone, 1978).

Ground-birds At least two species of kiwi (Apteryx australis and A. owenit) were identified from the

site. Because of the overlap in the range of their body sizes (Scarlett, 1972) it was not possible to identify to species the kiwi bones from the middle of the size range. However, examination of bones from each end of this range indicated that both species occurred in about equal numbers in Layer 3; that the abundance of A. australis decreased in Layer 2; and that this species probably was not present in Layer 1.

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Tab

le 2

-G

rou

nd

-bir

d c

omm

unit

y; s

how

ing,

for

ind

ivid

ual

spec

ies

from

eac

h la

yer,

the

min

imu

m n

um

ber

of

indi

vidu

als

(MN

I),

the

tota

l n

um

ber

of

bone

s (T

NB

), t

he p

erce

ntag

e o

f th

e gr

ound

-bir

d co

mm

unit

y th

at t

he s

peci

es c

ompr

ised

(P

GC

), a

nd

the

per

cent

age

of

all

indi

vidu

als

that

the

spe

cies

co

mpr

ised

(P

TS

).

Lay

er 1

L

ayer

2

Lay

er 3

M

NI

TN

B

PG

C

PT

S

MN

I T

NB

P

GC

P

TS

M

NI

TN

B

PG

C

PT

S

Apt

eryx

sp.

in

det.

(K

iwi)

2

5 2.

94

0.33

14

45

4.

90

1.19

10

35

6.

25

1.39

C

otur

nix

nova

ezel

andi

ae (

N.Z

. Q

uail

) 5

22

7.35

0.

83

5 12

1.

75

0.43

2

2 1.

25

0.28

Sy

noic

us y

psilo

phor

us (

Bro

wn

Qua

il)

2 4

2.94

0.

33

Ral

lus

phili

ppen

sis

(Ban

ded

Rai

l)

1 1

0.35

0.

08

Cap

ellir

allu

s ka

ram

u (E

xtin

ct S

nipe

-rai

l)

8 '2

8 11

.77

1.33

41

13

1 14

.33

3.50

22

61

13

.75

3.06

G

allin

ula

hodg

eni

(Ext

inct

Rai

l)

4 18

5.

88

0.66

32

10

9 11

.19

2.73

15

54

9.

37

2.09

G

allir

allu

s au

stra

lis (

W ek

a)

43

135

63.2

4 7.

14

133

530

46.5

0 11

.35

76

313

47

.50

10

.58

P

orza

na s

p. i

ndet

. (C

rake

) 2

5 2.

94

0.33

5

5 1.

75

0.43

3

5 1.

88

0.42

P

orph

yrio

man

telli

(N

oto

rnis

) 2

5 2.

94

0.33

44

25

6 15

.38

3.75

26

22

5 16

.25

3.62

F

ulic

a ch

atha

men

sis

(Ext

inct

N .Z

. C

oot)

8

27

2.80

0.

68

4 14

2.

50

0.55

C

oeno

cory

pha

auck

land

ica

(Sni

pe)

3 3

1.05

0.

26

2 3

1.25

0.

28

68

222

100

11.2

8 28

6 1,

119

100

24.4

0 16

0 71

2 1

00

22

.27

Tab

le 3

-F

ores

t-bi

rd c

omm

unit

y; s

how

ing,

for

ind

ivid

ual

spec

ies

from

eac

h la

yer,

the

min

imu

m n

um

ber

of i

ndiv

idua

ls (

MN

I),

the

tota

l n

um

ber

of b

ones

(T

NB

), t

he p

erce

ntag

e of

the

fore

st b

ird

com

mun

ity

that

the

spe

cies

com

pris

ed (

PF

C),

an

d t

he p

erce

ntag

e of

all

ind

ivid

uals

tha

t th

e sp

ecie

s co

mpr

ised

(P

TS

).

Lay

er 1

L

ayer

2

Lay

er 3

M

NI

TN

B

PF

C

PT

S

MN

I T

NB

P

FC

P

TS

M

NI

TN

B

PF

C

PT

S

Cir

cus

eyle

si (

Ext

inct

Haw

k)

2 6

3.17

0.

33

13

89

7.14

1.

11

12

118

11.0

1 1.

67

Cir

cus

appr

oxim

ans

(Har

rier

) 11

63

17

.46

1.83

5

9 2.

75

0.43

Fa

lco

nova

esee

land

iae

(N.Z

. F

alco

n)

2 10

3.

17

0.33

9

36

4.94

0.

77

4 16

3.

67

0.55

H

emip

haga

nov

aese

elan

diae

(N

.Z.

Pig

eon)

8

55

12.7

1 1.

33

28

171

15.3

8 2.

40

16

99

14.6

8 2.

23

Stri

gops

hab

ropt

ilus

(Kak

apo)

4

18

6.35

0.

66

34

187

18.6

8 2.

90

29

150

26.6

2 4.

04

Nes

tor

mer

idio

nalis

(K

aka)

6

26

9.52

1.

00

39

182

21.4

3 3.

33

18

119

16.5

1 2.

50

Cya

nora

mph

us n

ovae

zela

ndia

e (R

ed-c

row

ned

Par

akee

t)

6 15

9.

52

1.00

9

32

4.95

0.

77

6 17

5.

50

0.83

C

yano

ram

phus

aur

icep

s (Y

ello

w-c

row

ned

Par

akee

t)

1 2

1.59

0.

17

2 4

1.10

0.

17

1 1

0.92

0.

14

Nin

ox n

ovae

seel

andi

ae (

Mor

epor

k)

2 2

1.83

0.

28

Scel

ogla

ux a

lbifa

cies

(L

augh

ing

Ow

l)

2 4

1.10

0.

17

2 9

1.83

0.

28

Pro

sthe

mad

era

nova

esee

land

iae

(Tui

) 7

23

11.1

1 1.

16

5 15

2.

75

0.43

1

1 0.

92

0.14

St

urnu

s vu

lgar

is (

Sta

rlin

g)

6 20

9.

52

1.00

P

hile

stur

nus

caru

ncul

atus

(S

addl

ebac

k)

2 3

3.17

0.

33

8 14

4.

39

0.68

2

3 1.

83

0.28

C

alla

eas

cine

rea

(Kok

ako)

8

19

12.7

1 1.

33

19

73

10.4

4 1.

62

13

39

11.9

3 1.

81

Pala

eoco

rax

mor

ioru

m (

Ext

inct

Cro

w)

9 32

4.

95

0.77

3

14

2.75

0.

42

63

260

100

10.4

7 18

2 84

7 10

0 15

.55

109

587

100

15.1

7

'-l

l':l

'-c<

.: ;:; k ~

S. '" ~

~ k ~ " ~. ~

~

~

~ ~ '" ~ ~ I'>

...

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Horn - Subjossil avian deposits, Poukawa 73

There is some doubt whether Gallirallus minor (Extinct Weka) is a valid species, since it overlaps in size with small individuals of G. australis, and the bones of the two species are not morphologically different (Olson, 1975). Bones in the size ranges of both species were found in all three layers, but all are here attributed to G. australis.

A decrease was apparent in the abundance of several ground-bird species in Layer 1 compared with the two earlier periods. A considerable reduction in numbers of Porphyrio (Notornis) mantelli (Takahe) was evident. Capellirallus karamu and Gallinula hodgeni (extinct rails) were also reduced, as was Apteryx (Kiwi). Fulica chathamensis prisca (Extinct Coot), which has been found at only ten other North Island localities (Millener, 1981a) and was a minor component of the ground community in both early layers at this site, was not recovered from Layer 1.

Galliralus australis (Weka) and Coturnix novaezelandiae (New Zealand Quail) increased in abundance during this era, which suggests that they were better adapted than the previously mentioned members of the ground community to living in areas where the ground flora comprised mainly bracken (Pteridium esculentum) (McGlone, 1978).

F orest-birds This group also includes species normally found in areas of scattered trees and shrubs

e.g., Sturnus vulgaris, the Starling.

The relative abundance of Circus eylesi (Extinct Hawk) declined by 34% from Layers 3 to 2, and continued to decline into the era represented by Layer 1. Strigops harbroptilus (Kakapo), the most abundant of the forest bird species in Layer 3, declined by 28 %, and Nestor meridionalis (Kaka) increased by 33 % to become the most abundant forest bird in Layer 2. Both Strigops and Circus were only minor components of the assemblage in Layer 1. The abundance of Nestor and Hemiphaga novaeseelandiae (New Zealand Pigeon) also decreased, and Sceloglaux albifacies (Laughing Owl) and Palaeocorax moriorum (Extinct Crow) were not recorded from Layer 1. Two generalist specjes, Prosthemadera novaeseelandiae (Tui) and Cyanoramphus novaezelandiae (Red-crowned Parakeet), increased in abundance, as did Circus approximans (Australasian Harrier), which appeared to become established in the area Just over 1,000 years ago.

Bones of Sturnus vulgarus and Synoicus ypsilophorus (Brown Quail) were recovered from Maori midden deposits. The Brown Quail was introduced to New Zealand before 1870, and the Starling in 1862 (Oliver, 1955).

Sea-birds Sea-birds formed only a minor component of the total avifauna recorded. Bones of

Diomedea sp. (Mollymawk) had been manufactured into artefacts, and the other bones may have been from vagrant birds which flew inland.

Table 4 - Sea birds; showing, for individual species from each layer, the minimum number of individuals (MNI), the total number of bones (TNB), and the percentage of all individuals that the species comprised (PTS).

Diomedea sp. indet. (Mollymawk) Pachyptila sp. indet. (Prion) Puffinus griseus (Sooty Shearwater) Lams dominicanus (Black-backed Gull)

Layer 1 MNI TNB PTS

2 0.17 1 0.17

1 2 0.17 3 5 0.51

Layer 2 MNI TNB PTS

0.08 0.08

2 2 0.16

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Tab

le 5

-R

elat

ive

prop

orti

ons

of

body

par

ts r

ecov

ered

fro

m 1

3 m

ajo

r co

mpo

nent

s o

f th

e av

ifau

na.

Fo

r ea

sy c

ompa

riso

n, t

he r

esul

ts w

ere

stan

dard

ised

as

a p

rop

ort

ion

oft

he

mos

t ab

un

dan

t b

on

e fo

r ea

ch s

peci

es f

rom

eac

h la

yer.

Sim

ilar

bon

es f

rom

the

left

an

d r

ight

sid

es o

fth

e bi

rds

wer

e ad

ded

to

prod

uce

thes

e d

ata.

(F

=

fem

ur,

T

= t

ibio

tars

is,

M

= t

arso

met

atar

sus,

C

= c

orac

oid,

H

= h

um

eru

s, U

=

uln

a, S

ca

rpom

etac

arpu

s)

Lay

er 1

L

ayer

2

Lay

er 3

F

T

M

C

H

U

S F

T

M

C

H

U

S F

T

M

C

H

U

S

Apt

eryx

sp.

ind

et.

100

100

50

0 0

0 0

80

100

25

0 0

0 0

100

53

41

0 0

0 0

Cap

elli

rall

us k

aram

u 10

0 86

14

0

0 0

0 10

0 92

9

0 2

0 0

100

73

9 0

0 0

0 G

alli

nula

hod

geni

10

0 71

71

0

0 14

0

100

78

15

0 4

0 0

100

96

8 0

4 4

0 G

alli

rall

us a

ustr

alis

54

10

0 29

5

9 0

3 63

10

0 25

2

10

1 1

78

100

33

3 9

5 1

Por

phyr

io m

ante

lli

50

50

100

0 50

0

0 61

10

0 49

6

49

22

6 67

10

0 88

19

49

33

16

St

rigo

ps h

abro

ptil

us

50

100

17

0 33

0

33

71

100

52

12

19

17

61

67

100

32

4 11

9

28

Nes

tor

mer

idio

nali

s 27

10

0 0

18

45

9 18

41

10

0 13

39

89

28

15

29

10

0 13

65

97

52

16

H

emip

haga

nov

aese

elan

diae

27

33

7

100

60

33

0 32

29

42

10

0 10

0 79

5

36

32

8 10

0 96

76

0

Cyg

nus

sum

nere

ns!s

0

o 10

0 25

25

25

0

100

100

94

59

82

88

94

64

93

71

50

100

57

39

Eur

yana

s fi

nsch

i o

100

0 0

0 0

0 73

10

0 22

11

22

19

30

58

10

0 16

16

31

21

26

A

na

s su

perc

ilios

a 9

20

3 70

10

0 48

33

15

25

1

65

100

76

43

16

22

2 74

10

0 57

25

A

na

s gi

bber

ijro

ns

4 45

4

91

100

59

19

11

16

3 46

10

0 58

13

14

15

4

53

100

40

12

An

as

auck

land

ica

7 37

8

44

100

18

18

14

12

4 30

10

0 16

14

11

14

4

27

100

17

8

'-l

.;:..

~

~ ;:; ~

~

So '" ::tI

~ ~

~

" ;;; ~

~

~ ~ ~

." ~

;:! .".

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Horn - Subfossil avian deposits, Poukawa 75

Skeletal elements represented Many species from all three layers exhibited major differences in the various skeletal

elements represented (Table 5). For the abundant anatid species, the bone most frequently recorded was generally the humerus. Coracoids, ulnae, carpometacarpi and tibiotarsi were also well represented. The most common bones from the ralline, passerine, psittacine and ratite groups were femora and tibiotarsi, although wing bones of the Kaka were quite common. Coracoids, humari and ulnae were the most frequently found bones of Pigeon and Black Shag. The recovered skeletal elements of individual species appeared to be similar between the three layers. Very little cranial, sternal or pelvic material of any species was obtained.

DISCUSSION It is difficult to make reliable inferences concerning the composition of a prehistoric

avifauna from bone deposits. If the deposit is natural it does at least indicate species that were present in a particular area; but it is not always possible to distinguish bones which were deposited naturally from those which were the refuse of prehistoric hunting activity. Many of the recovered bones were cracked and broken, but this is a characteristic of both natural and midden deposits. Nor can it be assumed that hunters took each species in proportion to its local abundance, as ease of capture and palatability would surely influence a hunter's choice. Also, the occurrence of bones in middens does not necessarily mean that the birds were caught in the immediate area.

The duration of human occupation on Site N141112 is unknown. The cultural material recovered, including artefacts of Classic Maori types as defined by Golson (1959), indicate that the site was occupied between 150 and 300 years ago (McFadgen, 1979), and probably for some time before then (T. R. Price, pers. comm., 1973). McGlone (1978) estimated that forest destruction by fire began about 1,000 years ago in the Poukawa basin, and that this was the probable time of arrival of man in the area. Price's contention, that the avian remains from Sites N141/1 and N14112 (Price, 1963, 1965) and N141/12 (T. R. Price, peTS. comm., 1973) were associated with human occupation - thereby implying that man was present at Poukawa before 3,400 years B.P. - has evoked considerable controversy. Subsequent investigations by Pullar (1965, 1970), McGlone (1978) and McFadgen (1979), while considerably clarifying the stratigraphic sequence, have neither satisfactorily confirmed nor refuted Price's claims.

The avifauna of Layer 1 differs considerably from that of each of the two earlier periods. In particular, the proportion of water-birds increases at the expense of forest­birds, and, even more so, of ground-birds. These changes could be explained by the destruction offorest in the last 1,000 years, probably caused by fire (McGlone, 1978). This would have seriously affected the habitats of the forest- and ground-bird communities, but left the freshwater habitat relatively unchanged. However, the rate of deposition of bones in Layer 1 was virtually the same as the rate in Layer 2 for ground and forest dwelling groups, and much greater than in Layer 2 for the water-bird community. This suggests that another factor, possibly human activity, caused a higher rate of bone deposition in Layer 1, despite the destruction of the forest habitat during this time.

The large and flightless species (e.g., Takahe, Kiwi, Kakapo and Finsch's Duck) would have been easy prey for human hunters, and this probably resulted in their reduced abundance in Layer 1 and later local extinction. However, the decline of other species cannot be explained as easily. The decrease in relative abundance of both Shoveler and Scaup was unexpected, especially as the abundance of Grey Duck, Grey Teal and Brown Teal remained virtually unchanged over the 7,000 year period under examination.

Forest fires would certainly increase the chances of extinction of some species, particularly as large areas of the eastern North Island forest were destroyed in this way (Cameron, 1964). However, many of the larger bird taxa that are present in Layer 3 (Cygnus, Apteryx, Notornis, Circus, Strigops) decline in abundance in Layer 2, and appear

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76 Journal oj the Royal Society oj New Zealand

to have been drastically reduced in number before the beginning of the era represented by Layer 1. This indicates that, while fires and hunting activity in the last 1,000 years may have completed their local extinction, factors operating prior to this era initiated their decline.

There has been considerable speculation regarding the causes of the extinction of much of New Zealand's avifauna, particularly the larger species (review in Williams, 1973). It is widely agreed that two, climatic changes plus the dependent vegetational changes during the Holocene, and the activities of man, were particularly important. The effects of volcanic ash falls on the vegetation and fauna of the Poukawa region were unlikely to have been great. McGlone (1980) concluded that any forest modification caused by tephras would be erased in less than 70 years. As the Poukawa valley was on the extreme edge of the region of ash-fall of each of the four recorded tephras (Howorth et at., 1980; McGlone, 1980), it is likely that the period of influence of these phenomena would have been only a few years at most.

The paucity of bones of three now extinct species, Cnemiornis (Goose), Aptornis (Rail) and Harpagornis (Eagle), from the Poukawa region suggests that these birds were locally extinct or very rare at least 7,000 years B.P. Two bones of Cnemiornis and one of Aptornis were dredged from ancient blue sediments in a spring half a kilometre northeast of Site N141/12 (author's unpublished data). Bones of Cnemiornis and Harpagornis were recovered from Te Aute swamp (Hamilton, 1889), but no bones of these species have been recovered from Sites N 141/1, 2 or 12. If human activities had caused the extinction of these species at Poukawa then their remains probably would have occurred in Layers 1 or 2; hence it appears likely that some other agent, possibly climatic change, was responsible for their decline.

On the other hand, a non-climatic cause of avian extinctions is suggested by the differences in skeletal remains of the birds represented. This may have resulted either from differential survival of particular bones, or unequal deposition of body parts at the site. The scarcity of sternal and pelvic material found could be because these bones were usually in a poor state of preservation; but the under-representation of the easily identifiable and durable tarsometatarsi of many birds from all layers must be for another reason.

Studies of subfossil collections that report the numbers and types of bones found are scarce, so comparison of the Poukawa assemblage with others from either midden or natural deposits is difficult. In a study of bones from a midden site, Leach (1979) concluded that the uneven presence of different body parts indicated how the bird carcasses were "topped and tailed", and either eaten on the spot or preserved and transported to another site. Sutton and Marshall (1980) reported an uneven representation of skeletal elements of Pulfinus griseus (Muttonbird) at Tiwai Point, and concluded that the traditional manner of butchering and preservation of this species was the explanation.

McCulloch (1975) investigated a natural cave deposit of bones (mainly Euryanasji.nschl) in North Canterbury. Frequencies of occurrence of each of the nine major limb bones of this species were relatively similar, varying from 94 to 125. Virtually complete bird skeletons have often been found in North Island limestone caves (Millener, 1981b). Avian remains in dune deposits frequently become wind-scattered, hence small bones may be overlooked and delicate bones may be destroyed, leading to their under­representation in such collections (Dr P. R. Millener, pers. comm., 1982). Similar disturbances may have influenced the composition of the Poukawa avifaunal deposits, but they cannot explain the scarcity of crania or tarsometatarsi. No detailed data describing avifaunal deposits from swamps were available, so it was not possible to compare this material with a known natural swamp deposit. Until reasons are put forward explaining how such an uneven distribution of body parts can occur in natural bone deposits, I suggest that this material provides tentative support for Price's (1965) theory that man was present at Poukawa before 1,000 years B. P.

In summary, the assemblage of subfossil remains reported here indicates that during the last 7,000 years the Poukawa basin supported a large and diverse avifauna,

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Horn - Subjossil avian deposits, Poukawa 77

particularly after the formation of Lake Poukawa about 5,000 years ago. Major differences between the bird community compositions of Layers 1 and 2 are indicated, and are believed to be due mainly to forest destruction by man over the last 1,000 years. However, some species appear to have been under pressure before this time, probably from climatic changes, although human interference in the environment cannot yet be ruled out as a possible cause.

ACKNOWLEDGEMENTS I wish to thank Dr P. R. Millener, Mr M. M. Roche, Mr M. M. Trotter and Dr M. J. Winterbourn for their constructive criticism of the manuscript, and for helpful discussion. I am indebted also to Dr P. R. Millener, Mr R. J. Scarlett and Dr G. F. van Tets for assistance with bone identification, and to Mr T. R. Price who encouraged me to carry out this work and did much to enhance my interest in natural history.

REFERENCES Cameron, R. J., 1964.

the nineteenth century. Destruction of the indigenous forests for Maori agriculture during NZ Journal of Forestry 9: 98-109.

Davidson, J. M., 1978. The prehistory of Motutapu Island, New Zealand: Five centuries of Polynesian occupation in a changing landscilpe. Journal of the Polynesian Society 87: 327 -337.

Frith, H. J., 1977. Waterfowl in Australia. Angus and Robertson, Sydney, pp. 328.

Golson, J., 1959. Culture change in prehistoric New Zealand. In Freeman,]. D., and Geddes, W. R. (Eds.): Anthropology in the South Seas. Avery, New Plymouth, pp. 29-74.

Hamilton, A., 1889. Notes on a deposit of moa-bones in Te Aute swamp, Hawkes Bay. Transactions of the New Zealand Institute 21: 311-318.

Horn, P. L., 1980. Probable occurrence of the Black Bittern, Dupetor fiavicollis, in New Zealand. Notornis 27: 401-403.

Howorth, R., Froggatt, P. D. and Robertson, S. M., 1980. Late Quaternary volcanic ash stratigraphy in the Poukawa area, Central Hawke's Bay, New Zealand. N Z. Journal of Geology and Geophysics 23: 486-492.

Kear, J., and Scarlett, R. J., 1970. The Auckland Islands Merganser. Wildfowl 21 : 78-86.

Leach, B. F., 1979. Maximising minimum numbers: avian remains from the Washpool midden site. In Anderson, A. (Ed.): Birds of a Feather. NZ Archaeological Association Monograph II. BAR International Series 62, pp. 103-121.

McCulloch, B. D., 1975. Faunal remains from a cave at Waikari, North Canterbury. Unpublished Honours Project, Zoology Department, University of Canterbury, Christchurch, New Zealand, pp. 60.

McFadgen, B. G., 1979. The antiquity of man at Lake Poukawa, New Zealand. Journal of the Royal Society of NZ 9: 375-382.

McGlone, M. S., 1978. Forest destruction by early Polynesians, Lake Poukawa, Hawke's Bay, New Zealand. Journal of the Royal Society of NZ 8: 275-281.

1980. Forest fire following Holocene tephra fall. In Howorth, R., Froggatt, P. C., Vucetich, C. G., andCollen,J. D. (Eds.): Proceedings of Tephra Workshop. Department of Geology, Victoria University of Wellington, New Zealand. Publication No. 20, pp. 80-88.

Millener, P. R., 1981a. The subfossil distribution of extinct New Zealand coots. Notornis 28: 1-9.

1981b. The Quaternary avifauna of the North Island, New Zealand. Unpublished Ph.D. thesis, University of Auckland, New Zealand, pp. 897 (2 vols.).

Moore, P. R., and Tiller, E. M., 1975. Radiocarbon dates from New Zealand archaeological sites. NZ Archaeological Association Newsletter 18: 98-107.

Oliver, W. R. B., 1955. New Zealand Birds (2nd edition). A. H. & A. W. Reed, Wellington, pp. 661.

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78 Journal oj the Royal Society oj New Zealand

Olson, S. L., 1975. A review of the extinct rails of the New Zealand region. Records oj the National Museum oj N.z. 1: 63-79.

Olson, S. L., 1977. Notes on subfossil anatidae from New Zealand, including a new species of Pink-eared Duck Malacorhynchus. Emu 77: 132-135.

Price, T. R., 1963. Moa remains at Poukawa, Hawke's Bay. N Z Archaeological Association Newsleller 6: 169-174.

1965. Excavations at Poukawa, Hawke's BIlY, New Zealand. N.Z Archaeological Association Newsleller 8: 8-11.

Pullar, W. A., 1965. Note on ash beds at Poukawa, Hawke's Bay. N.Z Archaeological Association Newsleller 8: 11-13.

1970. Pumice ash beds and peaty deposits of archaeological significance near Lake Poukawa, Hawke's Bay. N.Z Journal oj Science 13: 687-705.

Rich, P. Y., and van Tets, G. F., 1981. The fossil pelicans of Australasia. Records oj the South Australian Museum 18(12).

Scarlett, R. J., 1966. A pelican in New Zealand. Notomis 13: 204-217.

1969. The occurrence of the Musk Duck, Biziura lobata (Shaw), III New Zealand. Notomis 16: 57-59.

1972. Bonesjor the New Zealand archaeologist. Canterbury Museum Bulletin No.4, pp. 69.

Sutton, D. G., and Marshall, Y. M., 1980. Coastal hunting in the Subantarctic Zone. NZ Journal oj Archaeology 2: 24-49.

Williams, G. R., 1964. Extinction and the Anatidae of New Zealand. Wildjowl Trust Annual Report 15: 140-146.

1973. Birds. In G. R. Williams (Ed.): The Natural History oj New Zealand. A. H. & A. W. Reed, Wellington, pp. 304-333.

Received 6 July 1982; accepted 11 February 1983.

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