Friday, April 3, 2009

Peregrine Falcon Scrape Site Selection

Hi All,
Bruce Connery of the National Park Service has contributed this informative blog about falcon nest site selection.
Enjoy!
All the Best,
Patrick Keenan
BioDiversity Research Institute


Peregrine Falcon Scrape Site Selection


The selection of a scrape, or nest site, for peregrine falcons occurs in tandem with other courtship activities and behaviors. The adults may visit several likely suitable ledges or structural platforms in the weeks leading up to the eggs being laid, seeking sites that have the right combination of factors such as aspect, exposure, and protection. Along with courtship activities such as pair flying and food exchanges, the adults often engage in ledge or scrape displays. These displays further strengthen the bond between the pair and also indicate possible nesting sites.

Falcons prefer scrapes that are composed of pea-sized gravels with small grains of sand or gravel and some soil, but where precipitation can drain away from the eggs, incubating adult, and eventually the chicks. Falcon scrapes may occur on natural or artificial structures but must be inaccessible from terrestrial predators and are often situated between vertical faces or walls above and below the scrape.

Natural candidate nesting sites can be open exposed ledges, ledges under an overhanging cliff, or raptor stick nests that the falcons claim for themselves from other raptors or from ravens that have an east to southern aspect. Scrapes on southeastern aspects provide morning warmth while protecting the adults and chicks from the hot mid- to late afternoon daytime temperatures that become common in late spring and early summer.

Artificial nest sites have good visibility and access and some protection from the sun and weather. Artificial sites may be the tops of bridge supports or structures, tops of buildings or on towers used in manufacturing complexes, but again must have a granular substrate that the adults can move around or hollow out into a depression to hold the eggs.

Nest boxes are often placed on towers, bridges, or other high locations were falcons have been observed at least perching and resting. The boxes can vary in size according to the dimension of the location they were they will be placed, however they must have sides that rise above and hold the granular substrate and have good drainage.

Bruce Connery
Biologist
National Park Service

21 comments:

  1. 4-2-09 5:10
    Thanks for the information. I really like what you did with the live cam shot and the view underneath it. We get the best of both, thanks.
    Judy in Western maine

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  2. 04/03 @ 18:53

    My thanks, also, for the additional information and for activating the second cam once again.

    The new box seems to be working well as I have not found stray eggs uncovered in a while. During exchanges I notice all four are nicely clustered.

    JAM in IL

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  3. Thanks, Bruce, for your very informative site selection writeup. I agree with JAM that the new box seems to function much better than the original.

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  4. Is sound available for Peregrine cam?

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  5. 4/16

    Does anyone know the approximate due date for the hatching of the peregrine falcons?

    cathy h in mass

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  6. approx hatch date is April 22.

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  7. checked in at 1:05 am and am hoping that my view is unclear due to the darkness. I will check again in the morning, but it appears the mommy is laying on the nest with her head cocked off to the side laying in the gravel. She has picked her head up slightly a few times but it goes right back down on the gravel. I haven't seen this behavior with her before.

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  8. checked this morning...she's fine. Whew!
    I was worried all night.

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  9. rainy day...poor mom is getting wet. Every so often she shakes off the water. Today is Tuesday...will be watching more often now as the eggs should begin hatching any day now.

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  10. the finch has hatched a few eggs, and has been feeding the new little ones......tho still nothing seen on the falcon nest... she is still sitting on the eggs.. maybe tomorrow an egg will hatch !!!???!!

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  11. 04/24 @ 12:34

    Finally resolved my computer problems and can once again view the nests! Guess I can start to worry about the eggs here ... most were left uncovered quite a bit in the beginning. Hopefully, at least one will hatch as I hate to see the pair have no positive results for all of their effort.

    JAM in IL

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  12. It is really awesome to be able to watch the mama and daddy finch feed the babies. Quite a site to behold.

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  13. 04/25 @ 08:58

    Murphy's Law (anything that can go wrong, will) seems to have hit some of our cams again. Tension mounts as we wait for an egg hatch here at Peregrine.

    I do have live feed for Eagle Cam 1 and the Osprey Cam (even though the Osprey still is not working). An osprey has been mostly down in the nest for a while this am. Don't know if there is a possibility of an egg or if this is incubating practice or if the bird is just resting.

    Patience, patience ...

    JAM in IL

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  14. the falcon cam is down again....... this is very disapointing..........

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  15. no cam since Friday. Hopefully it will be back up and running so we can see the babies. I keep hoping.

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  16. falcom cam is still not working....Maybe cause its time to switch out the ceramic fake eggs and place some live chicks in the nest ????

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  17. The nests are fantastic to watch. I can only imagine how time consuming they are to maintain. Perhaps if there were more staff members they could all be kept up and running without a hitch. Is there anyone willing to volunteer to help? Or to make a donation perhaps???

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  18. 04/27 @ 14:45

    Hooray ... cams back. Now if only we have a chick!

    JAM in IL

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  19. still 4 eggs in the nest..

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  20. 04/27 @ 18:24

    Sorry to read someone saw 4 eggs still. I was hoping for an egg hatching here. I suppose the next couple days will tell if the last eggs have a chance. The falcon keeps turning but I have not observed the change in position and have not had a glimpse of the eggs.

    Good news on the Osprey Cam ... first egg today. Don't know why that cam does not have a blog. All I find is the comment from May 2008.

    JAM in IL

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  21. What is that loud booming sound on the Peregrine cam coming from? Is it waves?

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