Roosting habits and post breeding dispersal of juvenile great egrets in ontario
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www.ec.gc.ca. Roosting habits and Post-breeding dispersal of juvenile Great Egrets in Ontario. D.V. Chip Weseloh & Dave Moore Canadian Wildlife Service - Ontario. With field assistance by Linda McLaren, Tyler Hoar and Dave Andrews. Harbor Herons and Waterbirds of Greater

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Roosting habits and post breeding dispersal of juvenile great egrets in ontario

www.ec.gc.ca

Roosting habits and Post-breeding dispersal of juvenile Great Egrets in Ontario.

D.V. Chip Weseloh & Dave Moore

Canadian Wildlife Service - Ontario

With field assistance by Linda McLaren,

Tyler Hoar and Dave Andrews

Harbor Herons and Waterbirds of Greater

NY/NJ Harbor Working Group

12-13 January 2011

Staten Island, NY


Objectives for 2010

Objectives for 2010

  • Confirm seasonal use pattern at major roost site.

  • Locate other roost sites, track numbers and usage.

  • Mark YOY egrets with highly visible wing-tags

  • Make greater efforts at re-sighting tagged egrets

    SUMMARY

  • Not used in spring, bimodal autumn peak #s

  • 30 roost sites;NN= 8, 24 km; Roost size = 2-400+

  • 118 egrets tagged at 3 sites

  • 39 individuals reobs., Egrets go to S. Ontario, Michigan, Ohio and NY- Few birds went north.


Roosting habits and post breeding dispersal of juvenile great egrets in ontario

Locations of colonies & nest numbers – 2000s

Dickerson Island

Bergin Island

High Bluff Island

Middle Island

Barrier Island

Nottawasaga Island

Lake

Huron

Lake

Ontario

Luther Marsh

Chantry Island

Toronto Harbour

Motor Island

Number

Number of

East Sister Island

of

Nests

Lake

Erie

Colonies

(maximum)

Decade

Middle Sister Island

1950s

1

1

1960s

2

10

1970s

4

63

1980s

4

108+

1990s

6

178

2000s

359+

11


Use of luther marsh roost site by week 2008 09

Use of Luther Marsh roost site, by week, 2008-09

300

2008

2010

2009

2009

2008

200

Opening day - duck hunting:

27 Sep. 2008

26 Sep. 2009

No. Great Egrets at Roost (mean/week)

100

no egrets present

0

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

1

Apr

May

Jun

Jul

Aug

Sep

Oct

Date


Use of luther marsh roost site by week 2008 10

300

2008

2010

2009

2009

2008

2010

200

No. Great Egrets at Roost (mean/week)

100

0

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

1

Apr

May

Jun

Jul

Aug

Sep

Oct

Use of Luther Marsh roost site, by week, 2008-10

Opening day - duck hunting:

27 Sep. 2008

26 Sep. 2009

25 Sep. 2010

no egrets present

Date


Roosting habits and post breeding dispersal of juvenile great egrets in ontario

Locations of Great Egret Roosts in the

Lower Great Lakes Region

= Confirmed Roosts

= Unconfirmed Roosts

= >100 Birds

27.

28.

29.

26.

30.


Roosting habits and post breeding dispersal of juvenile great egrets in ontario

GREG roosts –

nearest neighbour distances

15

mean = 84.6±47.2 km (N = 24)

Median = 24 km

Mode = 8 km

range = 1 – 160 km

10

No. Colonies

5

0

1-20 km

21-40 km

41-60 km

61-80 km

81-100 km

>100 km

Nearest Neighbour Distance


Roosting habits and post breeding dispersal of juvenile great egrets in ontario

Occupancy of GREG roosts, 2010

20

20

probable

confirmed

15

15

Number of confirmed & probable

roost sites occupied

10

10

5

5

0

0

1

1

2

2

3

3

4

4

1

1

2

2

3

3

4

4

1

1

2

2

3

3

4

4

1

1

2

2

3

3

4

4

1

1

2

2

3

3

4

4

1

1

Jun.

Jun.

Jul.

Jul.

Aug.

Aug.

Sep.

Sep.

Oct.

Oct.

Nov.

Nov.

Week


Roosting habits and post breeding dispersal of juvenile great egrets in ontario

4

Metcalfe

the Coves

3

2

1

0

1-Aug

8-Aug

25-Jul

3-Oct

5-Sep

15-Aug

22-Aug

29-Aug

10-Oct

12-Sep

19-Sep

26-Sep

Occupancy of small roosts, 2010

No. of GREGs at roost

Date


Roosting habits and post breeding dispersal of juvenile great egrets in ontario

Applying wing-tags


Roosting habits and post breeding dispersal of juvenile great egrets in ontario

Applying wing-tags


Roosting habits and post breeding dispersal of juvenile great egrets in ontario

Tagged egrets in the field


Roosting habits and post breeding dispersal of juvenile great egrets in ontario

Tagged egrets in the field


Roosting habits and post breeding dispersal of juvenile great egrets in ontario

Re-sightings of wing-tagged GREGs

All re-sightings,

2010

ON

ON

Nottawasaga

I.

Nottawasaga I.

2

Chantry I.

Chantry I.

5

8

5

6

2

3

NY

NY

2

MI

MI

Middle Sister I.

Middle Sister I.

PE

PE

OH

OH


Roosting habits and post breeding dispersal of juvenile great egrets in ontario

www.ec.gc.ca


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