An Urban Colony of Common Terns in Leith Docks
An Urban Colony of Common Terns in Leith Docks
An Urban Colony of Common Terns in Leith Docks
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<strong>Urban</strong> tern ecology: common terns<br />
<strong>in</strong> <strong>Leith</strong> <strong>Docks</strong><br />
Gemma Jenn<strong>in</strong>gs
Overview<br />
•Firth <strong>of</strong> Forth population<br />
•Imperial Dock Lock Special Protection Area (SPA)<br />
•Forag<strong>in</strong>g ecology<br />
•Predation<br />
•Summary
<strong>Common</strong> terns <strong>in</strong> the Firth <strong>of</strong> Forth<br />
• Formerly found on natural islands: e.g. Fidra, Inchmickery<br />
• <strong>Leith</strong> colony grew from 50 pairs <strong>in</strong> 1971 to 732 pairs <strong>in</strong> 2009<br />
• <strong>An</strong>alysis <strong>of</strong> long term data suggests colonisation occurred as<br />
a result <strong>of</strong> relocation from natural islands<br />
• Decl<strong>in</strong>e <strong>of</strong> tern colonies on natural islands largely due to<br />
<strong>in</strong>creas<strong>in</strong>g gull numbers
<strong>Common</strong> terns <strong>in</strong> the Firth <strong>of</strong> Forth<br />
1200<br />
1000<br />
800<br />
600<br />
400<br />
200<br />
1969<br />
1971<br />
1973<br />
1975<br />
1977<br />
1979<br />
1981<br />
1983<br />
1985<br />
1987<br />
1989<br />
1991<br />
1993<br />
1995<br />
1997<br />
1999<br />
2001<br />
2003<br />
2005<br />
2007<br />
2009<br />
0<br />
<strong>Colony</strong> Size (number <strong>of</strong> breed<strong>in</strong>g pairs)<br />
Data courtesy <strong>of</strong> JNCC.<br />
Year<br />
<strong>Leith</strong> <strong>Docks</strong><br />
Inchmickery
Imperial Dock Lock SPA<br />
• Special Protection Area for the common tern s<strong>in</strong>ce 2004<br />
• 5% British population<br />
• Largest colony <strong>in</strong> Scotland
<strong>Leith</strong> <strong>Docks</strong><br />
Images: Forth Ports
•Fieldwork May‐August<br />
•732 breed<strong>in</strong>g pairs<br />
•M<strong>in</strong>imum 0.6 chicks/pair<br />
2009 Breed<strong>in</strong>g Season
Forag<strong>in</strong>g Ecology<br />
Where
Forag<strong>in</strong>g Routes
Number <strong>of</strong> terns us<strong>in</strong>g each sector<br />
*<br />
*<br />
* P
Height <strong>of</strong> flight paths <strong>in</strong> the docks<br />
Most birds fly below 20m<br />
Error bars: 95% CI<br />
A: 0‐10m B:>10‐20m C:>20m
Forag<strong>in</strong>g Areas
JNCC Mar<strong>in</strong>e SPA Work<br />
•Exist<strong>in</strong>g SPAs provide protection at breed<strong>in</strong>g colony<br />
•Mar<strong>in</strong>e SPAs would protect important areas at sea,<br />
i.e. feed<strong>in</strong>g sites<br />
•JNCC to recommend possible mar<strong>in</strong>e SPAs for common,<br />
arctic, little, sandwich and roseate terns<br />
•Funded by SNH<br />
•Species‐specific habitat suitability models us<strong>in</strong>g...<br />
‐ exist<strong>in</strong>g mar<strong>in</strong>e habitat data<br />
‐ at‐sea tern distribution data
JNCC Mar<strong>in</strong>e SPA Work<br />
Wilson, L.J., B<strong>in</strong>gham, C.J., Black, J., Kober, K., Lewis, M., Webb, A. and Reid, J.B. (2009) Identify<strong>in</strong>g<br />
important areas for mar<strong>in</strong>e terns. Unpublished JNCC 1 st <strong>in</strong>terim report, December 2009
Forag<strong>in</strong>g Ecology<br />
What
Feed<strong>in</strong>g observations<br />
1) Courtship feed<strong>in</strong>g: scan sampl<strong>in</strong>g, whole colony<br />
2) Chick feed<strong>in</strong>g: focal nest observations, 20 nests<br />
• Recorded prey type and size (bill lengths)
Courtship feed<strong>in</strong>g<br />
Clupeids/gadids = 64%<br />
…but mostly clupeids!<br />
Sandeel = 36%<br />
Chick rear<strong>in</strong>g<br />
Clupeids = 68% (68%)<br />
Sandeel = 16% (25%)<br />
Gadids = 16% (8%)<br />
N = 2978<br />
N = 325<br />
>60% clupeids
Predation
Predation<br />
Crows<br />
Herr<strong>in</strong>g gull<br />
Lesser black‐backed gull<br />
~1 chick every 2 hours<br />
> Specialists
Predation and development<br />
• Possible <strong>in</strong>crease <strong>in</strong> predators<br />
…number and diversity<br />
e.g. rats, foxes, cats, plus gulls/corvids<br />
Major threat <strong>in</strong>direct via impact on predatory species<br />
> Waste control<br />
> Habitat management
Summary<br />
• Recent colonisation from natural Forth islands<br />
• Tolerate general dock activity –but response depends on tim<strong>in</strong>g<br />
and nature <strong>of</strong> disturbance<br />
• Flight paths widespread across sea wall, mostly below 20m<br />
• Ma<strong>in</strong> feed<strong>in</strong>g areas <strong>in</strong> the Firth <strong>of</strong> Forth, with<strong>in</strong> 10km <strong>of</strong> colony<br />
• Generalists, but feed mostly on clupeids: would suggest good<br />
stocks nearby<br />
• Major impact <strong>of</strong> development <strong>in</strong> the area is likely to be <strong>in</strong>direct,<br />
via effect on predatory species
Thanks!<br />
• Pr<strong>of</strong>. Bob Furness<br />
• Dr Derek McGlashan<br />
• JNCC Mar<strong>in</strong>e SPA Team‐ L<strong>in</strong>da<br />
Wilson, Kerst<strong>in</strong> Kober, Craig<br />
Bloomer<br />
• Lothian R<strong>in</strong>g<strong>in</strong>g Group ‐ John<br />
Davies<br />
• Ia<strong>in</strong> Muir<br />
• Dr Duncan Smallman<br />
• L<strong>in</strong>dsay Henderson<br />
• Zara Gladman<br />
g.jenn<strong>in</strong>gs.1@research.gla.ac.uk
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