Author Topic: Welcome to the Other Nests of Hornby Island (includes map) 2013 season  (Read 3871 times)

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Offline winterwren

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This thread is for discussions on the eagle's nests of Hornby Island in general. There are other threads for each individual nest, but sometimes the discussion is about trends that affect more than one nest. This is also where I will post my annual map of the nests we have found on the island.

Offline winterwren

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Re: Welcome to the Other Nests of Hornby Island (includes map) 2013 season
« Reply #1 on: October 03, 2013, 06:31:34 PM »
This is the map of the eagle's nests of Hornby Island for the 2013 season.

It looks very different from the previous map, which you can find here.
The 2011 map is here and the 2010 map is here. I have made some minor changes in the way I record things since 2010, so the comparisons with that year are less exact. Mainly I did not yet know that eagle pairs occasionally take a break for one year without abandoning their territory.  So the nests without issue for2010 show as vacant.

Click on the map to enlarge it; click again to examine areas in full size.



As usual, the coloured pins indicate active nests. The numbers on the heads of the pins are the number of eaglets for that nest. The pins with no white stickers or numbers indicate nests with no fledged eaglets. The pins with a white sticker and no number indicate a nest that has been active but whose issue is unknown. 

The labels show two previous years of stats for each nest.

The map shows 24 active nests, up from 22 in 2012 and 22 in 2011. The additions are a new nest at Big Tribune Bay, and Nest #3. Nest #3, or a new nest in that territory, has probably been active all along but we had no firm data on it until this year. In February, I watched an eagle pair mating at the bottom of the Shire while the Shingle Spit eagles were already accounted for elsewhere. Then in early summer, Booni was sent to capture a male eagle in that area. The eagle had a brood patch. The males of Shingle Spit and Phipps Point were both accounted for. So in this sad way we confirmed our long suspicion that there is an active nest in #3 territory.  The Tribune Bay eagles had reportedly been trying to build nests without success in previous years. This is their first successful attempt, with one eaglet fledged.

We confirmed the presence of 15 eaglets from these 24 nests. The numbers were 26 eaglets in 2012 and 23 eaglets in 2011.
Two eaglets got in trouble at fledging time and were rescued and sent to MARS: Big Blue from Nest #24, and an eaglet from Nest #20. These two eaglets are included as survivors on the map.

There was one probable fatality: Belcarra Nest showed signs of having offspring early on, and then all activity ceased.
Including Belcarra, there were 11 nests without issue this year. This is very high compared to 4 in 2012 and 4 in 2011.
Of those, Heron Rocks holds the distinction of having had no offspring for 3 years in a row, so there may be a fertility problem there.

Aside from the Big Tribune Bay eagles with their many nesting attempts, only one eagle pair moved this year: the Nest #32 eagles moved a few hundred metres inland from their long-standing home at Ford Cove.

As usual, the information on this map comes from nest surveys by Booni and myself, and from informal interviews with neighbours and visitors of the nests. My gratitude goes to everyone who contributed information.

Offline OpieK

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Re: Welcome to the Other Nests of Hornby Island (includes map) 2013 season
« Reply #2 on: October 03, 2013, 09:41:38 PM »
Thank you so much, Wren, for your detailed work - I'm sure it takes lots of time, and we appreciate it!