Do expectations about golden eagle Aquila chrysaetos ecology produce reliable guidance for species management?
David G Walker
1km squares used by resident Aquila chrysaetos, 1998-2010
(with scale of use)
1
7
2
8
3
9
4
10
5
11
6
12
1998
1999
2000
2002
2003
2004
2005
2006
2007
2008
2009
2010
Lepis timidus
Lagopus lagopus
2000
2001
2006
2013
Table 1: Breeding performance
Years Breeding years Young fledged
1988- 1993- 19981992 1997 2002 5 5 5 1 1 0 (1988) (1997)
20032007 4 0
Table 2: Breeding performance
Years Breeding years Young fledged
1988- 1993- 19981992 1997 2002 5 5 5 1 1 0 (1988) (1997)
20032007 4 0
20082012 3 5
Day 0
Day 10
Table 3: Estimated minimum available annual biomass (kg) 2005-2012
Food Source
2005
2006
2007
2008
2009
2010
2011
2012
1: Major resident
216.36
207.52
182.16
190.48
186.32
187.36
195.49
196.49
2: Other resident
101.12
101.12
101.12
101.12
101.12
101.12
101.12
101.12
3: Summer increase
126.60
126.60
129.26
131.82
131.82
131.82
131.82
131.82
4: Small spp
5.25
5.25
5.25
5.25
5.25
5.25
5.25
5.25
Total
449.33
440.49
417.79
428.67
424.51
425.55
433.68
434.68
Eggs laid
+
+
0
+
0
+
0
+
Young fledged
0
0
0
2
0
2
0
1
Estimated annual food requirements for pair rearing two young, at 0.23kg per bird per day, c.253.5kg (Watson 1997) Food Sources 1: Sheep carrion, Lagopus lagopus 2: Oryctolagus cuniculus, Vulpes vulpes, Ardea cinerea, Phasianus colchicus, Buteo buteo, Falco tinnunculus, Tetrao tetrix, Corvus corax, C. cornix, etc. 3: Sheep lambs, Larus canis, Numenius arquata, etc. 4: Small mammals, small passerines, passage spp, etc.
Table 4: Site history 1997-2013 year
eggs
young
1997
+
1
1998
+
0
1999
+
0
2000
+
0
2001
+
0
2002
+
0
2003
+
0
2004
+
0
2005
+
0
2006
+
0
2007
0
0
2008 2009 2010 2011 2012 2013
Known or probable cause of failure
Table 5: Site history 1997-2013 year
eggs
young
Known or probable cause of failure
1997
+
1
1998
+
0
Human disturbance?
1999
+
0
Nest collapsed
2000
+
0
Human disturbance
2001
+
0
Human activity (windfarm construction and habitat management)
2002
+
0
Human disturbance?
2003
+
0
Broken eggs (cause unknown)
2004
+
0
?
2005
+
0
?
2006
+
0
Bird lost in April
2007
0
0
Only one resident eagle during breeding season
2008
+
2
2009
0
0
2010
+
2
2011
0
0
2012
+
1
2013
+
0
Interference by juvenile fledged in previous year
Interference by juvenile fledged in previous year
Two small chicks died on nest
www.natural-research.org David.Walker@natural-research.org
Do expectations about Golden Eagle Aquila chrysaetos ecology produce reliable guidance for species management?
2000
Ari 1
Table 2: Simple site history (years with young fledged)
Young 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Notes
1
1
NRP project began
Adult lost from site in April 2006 Only one adult present
Table 3: Simple site history (years with young fledged)
Young 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Notes 1
1
NRP project began
Adult lost from site in April 2006 Only one adult present 2 2 1
Lagopus lagopus
Lepus timidus