Apparent Causes of Eaglet Deaths Seen on Webcams 2006-2013

compiled by JudyB, January 2014
 

Nest

Year

Details

Age

Cause

BC - Delta 1

2009

fell to its death when part of the nest gave way

24

fell

BC - Delta 2

2012

may have either gotten a bone caught in its crop, or eaten something lethal

51

unknown/other

BC - Harrison Mills

2013

younger of two died of sibling rivalry; it was 4 days younger, and there were a few days with little food

23

rivalry

BC - Hornby

2009

younger eaglet became tangled in adult's feathers & fell to death

11

fell

BC - Hornby

2010

solo eaglet died of acute aspergillosis, a respiratory infection

76

aspergillosis

BC - Lafarge

2010

younger chick failed to thrive; no obvious rivalry or lack of food

5

failure to thrive

BC - Lafarge

2013

youngest chick died within a day of hatching

<1

failure to thrive

BC - Lafarge

2013

middle chick died - perhaps unhealthy food; no obvious  rivalry; appeared normal until last day

11

unknown/other

CA - Grasslands

2008

female and chicks killed, probably by another female hoping to take over the nest

19

intruder/loss of adult

CA - Grasslands

2008

female and chicks killed, probably by another female hoping to take over the nest

18

intruder/loss of adult

CA - Two Harbors

2012

killed by island fox

22

predator

CA - Pelican Harbor

2009

died shortly after hatching - not sure why

3

failure to thrive

CA - Pelican Harbor

2009

died shortly after hatching - not sure why

4

failure to thrive

CA - Turtle Bay

2013

killed by new male trying to take over the nest

<1

intruder/loss of adult

CA - Turtle Bay

2013

killed by new male trying to take over the nest

<1

intruder/loss of adult

CO - Fort St Vrain

2009

one adult disappeared; the remaining adult eventually left the chicks to get food, and they died of the cold

21

intruder/loss of adult

CO - Fort St Vrain

2009

one adult disappeared; the remaining adult eventually left the chicks to get food, and they died of the cold

21

intruder/loss of adult

CO - Fort St Vrain

2009

one adult disappeared; the remaining adult eventually left the chicks to get food, and they died of the cold

17

intruder/loss of adult

CO - Fort St Vrain

2012

got caught in branches near the edge of the nest and died from exposure overnight

6

unknown/other

CO - Fort St Vrain

2012

died from exposure during severe wind/rain storm

18

weather

CO - Fort St Vrain

2012

died from exposure during severe wind/rain storm

14

weather

CO - Fort St Vrain

2013

died during large snowstorm with over a foot of snow on the nest

15

weather

CO - Fort St Vrain

2013

died during large snowstorm with over a foot of snow on the nest

18

weather

IL - Miss River Refuge

2012

crawled near edge of nest and fell (parents often away from nest)

3

fell

IL - Miss River Refuge

2012

crawled near edge of nest and fell (parents often away from nest)

4

fell

ME - Hancock County

2006

youngest of three died from sibling rivalry

~10

rivalry

ME - Hancock County

2007

at least one chick died in massive wind/rain storm shortly after hatching

5

weather

ME - Hancock County

2012

younger of two died of sibling rivalry after bad weather led to shortage of food

35

rivalry

ME - Hancock County

2013

younger of two died of sibling rivalry after bad weather led to shortage of food

42

rivalry

MD - Blackwater

2012

killed by intruder while adults were away from the nest

8

intruder/loss of adult

MD - Blackwater

2012

killed by intruder while adults were away from the nest

9

intruder/loss of adult

MD - Blackwater

2013

youngest of three died from weather + sibling rivalry; 5 days younger & bad storm prevented feeding

5

rivalry

MA - Barton's Cove

2008

no rivalry observed, but it could have happened; more likely failure to thrive

3

failure to thrive

MN - MN Bound

2012

was standing on piece of skin and was tossed to side of nest when adult moved it, then fell to its death

16

fell

MO - Lake of Ozarks

2011

likely blown from nest in bad windstorm

16

fell

MT - Libby Dam

2009

possibly rivalry - hard to tell on a refresh cam

20

unknown/other

NC - CRC

2010

died shortly after hatching

<1

failure to thrive

NC - CRC

2011

cause not known; seemed smaller and weaker; no apparently rivalry and plenty of food

26

unknown/other

NC - CRC

2013

killed by predator, likely raccoon

26

predator

OK - Sequoyah

2012

youngest of 3 died of exposure during a storm, but was smaller and less developed due to sibling rivalry

39

rivalry

OK - Sooner Lake

2010

blown across the nest by heavy gust of wind and fell through a hole near the edge to its death

2

fell

OK - Sooner Lake

2010

fell from the nest, probably after losing its balance while learning to stand (nest was somewhat flimsy)

36

fell

OK - Sooner Lake

2012

cause of death not certain; may have been stepped on by adult

7

unknown/other

OK - Sooner Lake

2013

died shortly after hatching

<1

failure to thrive

OK - Sooner Lake

2013

died from sibling rivalry, probably aggravated by a spell of very cold weather

6

rivalry

WA - Lake Washington

2008

cause unknown - it was a refresh cam, and not a lot of people were watching

~60

unknown/other

WA - Lake Washington

2011

likely fledging mishap

84

unknown/other

WV - NCTC

2007

one chick may have hatched as a blizzard was approaching; no chicks were seen after the storm

<1

weather

WV - NCTC

2011

intruder apparently killed the male, and kept the female from leaving to get food

3

intruder/loss of adult

Summary:

Aspergillosis - 1
Non-Eagle Predator (attacks by other eagles are under nest disruption) - 2
Weather (blizzards, heavy wind and rain, etc) - 6
Failure to Thrive (includes those who didn't recover from the work of hatching) - 7
Sibling Rivalry (either direct attacks or by keeping a younger eaglet from getting food) - 7
Fell from nest (poor nest construction, windy conditions, etc) - 8
Unknown or Other - 8
Nest Disruption (intruder, loss of adult, etc) - 10 (includes 2 lost at the Grasslands nest in 2008, where there was no cam, but the cause was known)

Total - 49 - plus 11 additional chicks lost at nests without cams; in some cases observers had some suspicions as to what might have happened, but without at least daily observation, it's hard to be sure.

Please note that these are the webcams and other nests I've been following - there are no doubt others I haven't discovered yet. ~JudyB

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