Growth of the Osprey Pandion haliaetus population

in the Orleans Forest 1984 - 2003

data collected by "les Naturalistes Orleanais" 1985 - 1994, and by Rolf Wahl from 1995 unwards

graphs made by Ruud Kampf

no use without permission!

(E-mail: rowahl@rekel.nl)


2003

occupied

succesful

nr of young

nr of young per nest

nr of young per succesful nest

Orleans forest

14

11

27

1.93

2.45

Chambord

4

2

5

1.25

2.5

grand total

18

13

32

Plus one nest in Isle de France, near Paris


number of nests per year_orleans_total and succesful.PNG (21352 bytes)

After initially a long period with only one succesful pair the population keeps growing

Orleans forest_total nr of young.png (7931 bytes)

From 1985 to 2002 a total number of 140 young has fledged.

fit_nests_from_1990_2003.PNG (24400 bytes)

This fit of the number of occupied nests shows that the population still grows with an exponential rate, partially because of the influx of birds from the German population.

The equation of the fitted model is:

Year_nests = exp(-328.304 + 0.165202*year)
Since the P-value in the ANOVA table is less than 0.01, there is a statistically significant relationship at a 99% confidence level.

young_succ_pair_c_o.PNG (23552 bytes)

The breeding success of the Orleans "colony" is with 2.27 young per succesfull nest since 1989 very good (2.07 per breeding pair). The new "colony"in the Chambord forest gives comparable results.


The spacial development of the population in the Orleans forest from 1990

1990.jpg (4892 bytes) 1991.jpg (5146 bytes)
1992.jpg (4873 bytes) 1993.jpg (5090 bytes)
1994.jpg (5223 bytes) 1995.jpg (5448 bytes)
1996.jpg (5422 bytes) 1997.jpg (5533 bytes)
1998.jpg (5453 bytes) 1999.jpg (5438 bytes)
2000.jpg (5784 bytes) 2001.jpg (7030 bytes)
2002.jpg (7017 bytes)

2003.jpg (7373 bytes)

The area on the graphs covers 30 km times 40 km in the Orleans forest


With many thanks to Rolf Wahl, specialist on Ospreys in the Orleans Forest for the hospitality and company

When you find any information on Ospreys with colored rings in France, please contact Rolf Wahl

(E-mail:rowahl@rekel.nl)


back to the Osprey index page of Ruud Kampf

Home page Ruud en Kitty Kampf

Email: ruud@rekel.nl