statistics in ecology
Download
Skip this Video
Download Presentation
Statistics in Ecology

Loading in 2 Seconds...

play fullscreen
1 / 63

Statistics in Ecology - PowerPoint PPT Presentation


  • 109 Views
  • Uploaded on

Statistics in Ecology. Alison Johnston British Trust for Ornithology. Spatial population trends Migrant declines Spatial abundance Massimino et al. In prep. Common bird Census. Breeding Bird Survey. Common bird Census. Breeding Bird Survey. Distance sampling & Detectability.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Statistics in Ecology' - horace


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
statistics in ecology

Statistics in Ecology

Alison Johnston

British Trust for Ornithology

slide4

Spatial population trends

Migrant declines

Spatial abundance

Massimino et al. In prep

slide5

Common bird Census

Breeding Bird Survey

slide6

Common bird Census

Breeding Bird Survey

distance sampling detectability
Distance sampling & Detectability

Nuthatch Sitta europaea

Curlew Numenius arquata

slide9

Grey partridge

Lapwing

Turtle dove

Greenfinch

Yellowhammer

Whitethroat

Skylark

slide10

Arithmetic mean

Geometric mean

Species 1: t1 = 0.5

Species 2: t2 = 2.0

slide11

Grey partridge

Lapwing

Turtle dove

Greenfinch

Yellowhammer

Whitethroat

Skylark

Geometric mean

slide13

Common bird Census

Breeding Bird Survey

slide14

Modelling bird abundance - GAMs

ln(μit) ~ land coveri+ island

+ smooth (eastingi, northingi)

+ offset (detectabilityit)

2nd run

1st run

- response variable the number detected in a 1km square

- smoothed geographical differences in abundance

- non-linear changes in land-use and abundance

94

95

96

97

98

99

00

01

02

03

04

05

06

07

08

09

slide15

GAMs

df» 15

df» 8

df» 3

slide16

ln(μit) ~ land coveri

+ smooth (eastingi, northingi)

+ offset (detectabilityit)

slide24

Newson et al. 2011. J. ApplEcol

Johnston et al. In submission

Davey et al. 2012. Glob. Ecol. Biogeog.

Pearce-Higgins et al. 2012

gams pros and cons
GAMs – pros and cons

Flexibility

- non-linear relationships

- more biologically realistic models

Flexibility

- how much?

- overfitting

- model selection

Smooths can account for effect of variables of interest

Good for descriptive models

Require more care for explanatory models

slide26

Spatial population trends

Migrant declines

Spatial abundance

Ockendon et al. 2012 Bird Study

www.xkcd.com

slide31

Breeding habitat

Bioclimatic wintering zone

Wintering habitat

Median arrival date

Trend in arrival date

Median*trend interaction

north

arid

humid

south

● woodland

× general

△ wetland

○ open

slide32

POP TREND ~ breeding habitat

+ wintering habitat

+ bioclimatic zone

+ median arrival * trend arrival

weight (1/trend.se)

slide34

POP TREND ~ breeding habitat

+ wintering habitat

+ bioclimatic zone

+ median arrival * trend arrival

weight (1/trend.se)

slide36

Spatial population trends

Migrant declines

Spatial abundance

Johnston et al. In submission

motivation
Motivation
  • Baseline EU target 20% of energy from renewable sources by 2020
  • This requires substantial contribution of offshore wind
  • Internationally important seabirds breeding on UK coast
  • Seabirds long-lived species with low productivity

“For the vast majority of the birds that fly in near shore and offshore areas, very little is known.

This lack of data is of particular concern,

given the large scale of proposed offshore windfarms, and the probability of cumulative effects”

Drewitt & Langston 2006

impact assessment
Impact Assessment

A description of the aspects of the environment likely to be significantly affected by the proposed project including, in particular, population, fauna, flora, water...

“are likely to have a significant effect on the conservation status of European protected species”

Habitat change/loss (positive or negative)

Changes in prey or predators (positive or negative)

Disturbance causing displacement or behavioural change

Collision with structures

Additional energy cost of avoiding structures

dogger bank development
Dogger Bank Development

Slow survey

Detectability

95% ID

Visual observations

Snapshot count

All birds seen

24% ID (13% certain)

Digital images

“are likely to have a significant effect on the conservation status of European protected species”

slide40

Black-headed gull

Razorbill

Large gull (gannet/great black-backed gull/lesser black-backed gull)

Large auk (razorbill/guillemot)

Kittiwake

Small bird (lots)

razorbills

large auks

~ f(day) + behavior + latitude + longitude

Johnston et al. In prep

slide41

Black-headed gull

Black-headed gull

Razorbill

Razorbill

Large gull (gannet/great black-backed gull/lesser black-backed gull)

Large gull (gannet/great black-backed gull/lesser black-backed gull)

Large auk (razorbill/guillemot)

Large auk (razorbill/guillemot)

Kittiwake

Kittiwake

puffin

Small bird (lots)

Small bird (lots)

fulmar

Johnston et al. In prep

slide42

Black-headed gull

Black-headed gull

Black-headed gull

Black-headed gull

Razorbill

Razorbill

Razorbill

Razorbill

great black-backed gull

gannet

great black-backed gull

lesser black-backed gull

guillemot

razorbill

guillemot

guillemot

Kittiwake

Kittiwake

Kittiwake

Kittiwake

Little auk

fulmar

puffin

kittiwake

impact assessment1
Impact Assessment

A description of the aspects of the environment likely to be significantly affected by the proposed project including, in particular, population, fauna, flora, water...

“are likely to have a significant effect on the conservation status of European protected species”

slide44

Kittiwake

kittiwake

slide45

Kittiwake

kittiwake

slide47

0

1

0

1

0

0

1

0

1

0

0

0

0

0

1

0

0

2

3

3

0

0

2

1

0

0

0

2

3

2

abundance modelling
Abundance modelling

abundance ~ sea_surface_temp + depth + distance_coast + distance_colonies

+ sandeel_boats + season + season interactions + f(day)

+ correlation(lat, long) + offset(effort)

slide52

No certain seen

No we could have seen

x 119

slide53

No certain seen

No we could have seen

No. modelled to be in whole area

slide54

Great black-backed gull

Larusmarinus

J F M A M J J A S O N D J F M A M J J A S O N D

2010 2011

slide55

Puffin

Fraterculaarctica

J F M A M J J A S O N D J F M A M J J A S O N D

2010 2011

assumptions
Assumptions
  • Certain and probable species IDs are recorded accurately
  • In boat surveys all individuals on the transect line are detected and identified
  • Boat observations do not affect the proportions of species detected
  • All stages of modelling are independent to enable accurate error propogation

Conclusions

  • Many species have a high proportion of individuals not identified
  • Randomised ‘best guesses’ can vastly improve estimates of abundance
  • Now able to estimate species-specific distributions and abundances
  • Propogation of error from all stages of the process
  • Final confidence limits account for all sources of uncertainty including uncertainty in species ID.
slide57

Spatial population trends

Migrant declines

Spatial abundance

www.xkcd.com

slide63

Razorbill

Black-headed gull

lesser black-backed gull

Kittiwake

guillemot

kittiwake

ad