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Landscape scale analysis of the value of waterbirds in the Alligator Rivers Region,

northern Australia

MG Bellio1, P Bayliss1 & P Dostine2

1 Environmental Research Institute of the Supervising Scientist GPO Box 461, Darwin NT 0801

2 Department of Infrastructure, Planning and Environment, PO Box 30, Palmerston NT 0831

March 2004

Registry File SG2002/0196

1

Landscape scale analysis of the value of waterbirds in the Alligator Rivers Region,

northern Australia

MG Bellio, P Bayliss & P Dostine

Abstract The coastal and alluvial floodplains of the Alligator Rivers Region (ARR) support an outstanding diversity and abundance of flora and fauna, and encompasses Kakadu National Park. The region is extremely important to Aboriginal people, and many communities still use the floodplains as a source of traditional food, in particular geese and ducks. Kakadu National Park is inscribed on the World Heritage List because of its outstanding cultural and natural universal values, and its wetlands are listed under the Ramsar Convention on Wetlands of International Importance.

In 1999 the World Heritage Committee recommended that landscape and ecosystem analyses of the entire region be undertaken to help protect the ecological and cultural integrity of Kakadu. In response to this recommendation the Supervising Scientist Division of Environment Australia has commenced a number of landscape-wide projects that link various threats and pressures to ecosystems of the ARR (e.g. mining, invasive species, climate change & salinisation), in particular wetlands, in order to outline risk management strategies. Waterbirds are a key component of tropical wetlands and occupy several trophic levels. They are also potential indicators of ecological condition and have high cultural and natural significance. We are developing a conceptual model which directly links waterbird dynamics to the quality of their wetland habitats, both in terms of the availability of food and nesting resources. Being able to use the abundance and diversity of waterbirds as key indicators of “wetland health” and determining the efficacy of this approach is a key issue.

Key words: waterbirds, world heritage values, landscape analysis, cultural and natural resource management

2

3

Landscape scale analysis of the value of waterbirds in the Alligator Rivers Region

M BELLIO – P BAYLISS - P DOSTINE – J BOYDEN-M FINLAYSON

Supervising Scientist

VAN DIEMEN GULF

The Alligator Rivers RegionThe Alligator Rivers Region

4

• KAKADU NATIONAL PARK

1. World Heritage Area (natural and cultural)

2. Ramsar Convention

• ABORIGINAL PEOPLE own much of the land in the Region and several groups continue to utilise the natural resources in a semi-traditional manner

• IMPORTANT MINERAL RESERVES (URANIUM)

• PASTORALISM

• TOURISM

BackgroundBackground• Approval for a new uranium Mine (1998) –

Jabiluka

• Meeting in Tokyo Nov 1998– Bureau of World Heritage Committee expressed its concern – threat to World Heritage Values

• Mission was sent to Kakadu – Jabiluka stopped

• ISP recommendation : comprehensive risk assessment of both the freshwater and terrestrial ecosystem at a landscape-catchment scale

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Landscape projects AimsLandscape projects Aims• Collect baseline information at a landscape

scale on flora fauna and their habitat

• Separate impact of mining from unrelated mining activities:

• Highly variable environment• Different land uses• Weeds• Ferals• Climate change

What we need to assessWhat we need to assess•• When they occur ( seasonal patterns)When they occur ( seasonal patterns)

•• Identify vulnerability at each time of the yearIdentify vulnerability at each time of the year

•• Identify ecological drivers (individual sp. Identify ecological drivers (individual sp. –– guilds)guilds)

•• Identify habitat usage (individual sp.Identify habitat usage (individual sp.–– guilds)guilds)

•• Predictive aspect Predictive aspect –– how species respond to environmental how species respond to environmental perturbations (natural or human induced)perturbations (natural or human induced)

•• How we maintain the ecological value of those areas How we maintain the ecological value of those areas (World Heritage Values)(World Heritage Values)

6

What we already knowWhat we already know• Systematic aerial surveys of the Top End (1983-1990)

(data published) - Bayliss & Yeomans (1990)

• OSS : systematic aerial and ground surveys ARR (1981-1984) (data published) - Morton et al. (1990)

• PWCNT: aerial surveys – hot spots (data published) – Chatto (2000- 2001-2003)

• OSS : Individual condition and diet (21 species) (some data published) – Dostine (1988, 1989, 2000)

Developing Conceptual modelsDeveloping Conceptual models

Distribution and Abundance

Ecological Drivers Food availability

Nesting –Spacing behaviour

Individual condition

Diet food intake

Developing conceptual models incorporating the basic ecological factors affecting the functioning of the wetlands, and dynamics upon which these ecosystems are regulated.

Habitat

Reproductive condition

Population Dynamics

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At the Level of Individual At the Level of Individual Green Pygmy GooseGreen Pygmy Goose

• Small tropical duck largely unstudied

• Inhabits floodplains and lagoons of the ARR and Northern Australia

• Known to feed on water lilies and other aquatic plants, but also range of aquatic animals

• Processes which diminish diversity of diet items (weeds invasion, loss of habitat) will lower habitat quality for this species

Reproductive condition Green Pygmy Goose

2.00

3.20

1.14

3.72

1.41 1.25

2.96

6.23

1.83

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

Ave

rage

dim

ensi

on o

f fol

licle

s

ED-81 EW -81-82

ED-82 LW 83 ED 83 LD 83 EW83/84

LW 84 ED 84

Season

Green Pygmy goose-Female gonads development across seasons

1981 - 1984

1981-1982 1982-1983

1983-1984

Correlation female gonads development and rainfall

y = 0.0099x + 1.402R2 = 0.8179 r=0.904 df=7 p<0.001

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

0 100 200 300 400

Rainfall (mm)

Aver

age

dim

ensi

on

folli

cles

EW – Nov Dec Jan

LW – Feb Mar Apr

ED - May June Jul

LD – Aug Sep Oct

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Reproductive condition Green Pygmy Goose

1981-1982 1982-1983

1983-1984

22.75

86.06

19.95

49.16

22.3216.11

29.81

49.16

32.01

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

Ave

rage

dim

ensi

on o

f tes

tes

ED -81

EW -81/82

ED-82 LW-83

ED 83 LD 83 EW -83/84

LW 84 ED 84

Season

Green Pygmy Goose Male gonads development across seasons

1981 - 1984

Correlation males gonads and rainfall

y = 0.1198x + 21.466R2 = 0.6462 r=0.803 df=7 p<0.01

0.0010.0020.0030.0040.0050.0060.0070.0080.0090.00

100.00

0 100 200 300 400

Rainfall (mm)

Aver

age

gona

ds d

imen

sion

1981-19821982-1983 1983-1984

EW – Nov Dec Jan

LW – Feb Mar Apr

ED - May June Jul

LD – Aug Sep Oct

Individual condition Body Weight

310.00

320.00

330.00

340.00

350.00

360.00

370.00

380.00

Bod

y w

eigh

t

ED 81 EW81/82

ED 82 LW83

ED 83 LD 83 EW83/84

LW84

ED 84

Season

Pattern of body weight across seasons

Body weight and Rainfall

y = -0.0865x + 368.37R2 = 0.6832 r=0.827 df=7 p<0.01

330.00335.00340.00345.00350.00355.00360.00365.00370.00375.00380.00

0 100 200 300 400Rainfall (mm)

Wei

ght (

gr)

1981-1982

1982-19831983-1984

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EWLDEDLW

Aquatic plants seeding

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Nymphaea violacea

Blyxa echinosperma

Hydrilla verticillata

Hygrochloa aquatica

Nymphaea macrosperma

Investigating population dynamics –Inductive approach

Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul

Gonads dev.

Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul

√ √ √ √ √ √ √ √

Plants √ √ √ √ √ √ √ √ √ √ √ √ √Invertebrates √ √ √ √ √ √ √ √√ √ √ √ √ √

Body condition √ √ √ √ √ √ √ √√ √ √ √ √ √

Ducklings √ √ √ √ √ √ √ √

Good wet season= plenty of food, good survival and recruitment ?

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Investigating population dynamics –Inductive approach

Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul

Gonads dev.

Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul

Plants Invertebrates

Body condition

Ducklings

Poor wet season= less food , stress for survival, low recruitment ?

√ √ √ √ √ √

√ √ √

√ √ √√ √ √√ √ √√ √ √

√ √ √

Gaps in KnowledgeGaps in Knowledge

• Life history parameters :-fecundity rate-rate of survival-age structure of population-proportion of breeders

• Movements across floodplains- immigration and emigration

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Green Pygmy Geese - Rate of increase between seasons

-0.0300

-0.0200

-0.0100

0.0000

0.0100

0.0200

0.0300

0.0400

0.0500

LD 8

1

EW 8

1/82

LW 8

2

ED 8

2

LD 8

2

EW 8

2/83

LW 8

3

ED 8

3

LD 8

3

EW 8

3/84

LW 8

4

ED 8

4

LD 8

4

Seasons

Rat

e of

incr

ease

r=0.0372

r=0.0141

r=0.0295

r= (Ln Nt –Ln Nt0 ) /t

1981-1982 1982-1983

1983-1984

Population dynamicsPopulation dynamics

0

100

200

300

400

500

600

700

Rai

nfal

l (m

m)

Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun JulMonths

Monthly Rainfall

80/81 81/82

82/83 83/84

1981-1982 good

1982-1983 bad

1983-1984 good

recruitment

movements between floodplains immigrationmovements between floodplains emigration

r= ∑(birth – death) + (immig.-emigr.)

Rate of Increase and rainfallTime lag response

r= ∑(birth – death) + (immig.-emigr.)

y = 3E-05x - 0.0169R2 = 0.9044 r=0.951 p<0.001 df=7

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0.05

0 500 1000 1500 2000

In situ –change in resources Long term lag response

Movements Short term lag response

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Developing Conceptual modelsDeveloping Conceptual models

Distribution and Abundance

Rainfall Regime Food availability

Nesting –Spacing behaviour

Individual condition

Diet food intake

Developing conceptual models incorporating the basic ecological factors affecting the functioning of the wetlands, and dynamics upon which these ecosystems are regulated.

Habitat

Reproductive condition

Population Dynamics

Resource LimitationResource Limitation

• Spacing behaviour: inter and intra competition nesting and foraging space

• Habitat usage – spatial distribution at a landscape scale

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Habitat FeaturesHabitat FeaturesThe Alligator River Region encompasses diverse waterbirds habitat.

Some of the areas are very remote and difficult to access.

Identify Habitat FeaturesIdentify Habitat Features• Investigate potential of remote sensing to map and

to monitor waterbird habitats

• Develop indexes of habitat suitability

• Investigate patterns of distribution and abundance in relation to habitat suitability

• Assess threats to these habitat

• Management needs to maintain the ecological values of these habitats

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•90 Km2 of swamp

•Important dry season refuge for waterbirds

•75% Magpie Geese Top End population

•Decrease 18 years

•Hymenachne

•Buffalo

Remote sensingRemote sensingBoggy Plain - ARR

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Relating distribution to Relating distribution to environmental dataenvironmental data

• Investigate the use of GIS to correlate environmental data from a number of sources to bird distribution data

• Use of multivariate statistic to identify groups of species that are likely to respond in similar ways to environmental perturbations

Where from nowWhere from now

• Collate historical information and undertake gap analysis in knowledge

• Developing conceptual models to link ecological drivers to patterns of distribution

• Investigate the use of remote sensing to map habitat and assess and monitor threats to habitat

• Investigate the use of GIS to relate distribution to environmental data

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OutputsOutputs• Series of Reports on remote sensing –

conceptual models : www.deh.gov.au

• Developing collaborations with other institutions NGO to develop modelling and explore the predictive aspect

• Feeding National and International Programs on Waterbirds Conservation

Communication StrategyCommunication Strategy

• Project in collaboration with Traditional Owners (TO)

• Parks Australia North

• PWCNT

• Other NGO – Universities and Institutions interesting in sharing information

• Raise awareness and provide information at a Local, National and International level

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THANK YOUTHANK YOU