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Author Topic: Turtle remains / turtle habits on Niku  (Read 15442 times)

John Kada

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Turtle remains / turtle habits on Niku
« on: September 05, 2011, 09:38:10 PM »

Hello,

The remains of a turtle were found along with the partial skeleton found by the settlers in 1940. I'm wondering if turtles would have been present at Nikumaroro all year round, or perhaps only part of the year (egg laying season?). If the latter, then then the turtle remains would suggest the time of year at which the castaway was making camp at the Seven site (I am assuming here that the castaway ate the turtle, and not the other way around...). If this angle hasn't already been looked into, it would be interesting discuss this point with a turtle expert, no?

Were turtles seen on Niku during any of Tighar's expeditions? I seem to recall reading something about live turtles on Niku, perhaps in relation to the colonists rather than to Tighar, but don't know where I read this...

« Last Edit: September 05, 2011, 09:58:47 PM by John Kada »
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Irvine John Donald

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Re: Turtle remains
« Reply #1 on: September 05, 2011, 10:12:27 PM »

But it doesn't mean the turtle was eaten by the castaway but just at the same place.  Have you ever been out camping and found someone elses camp site?  Maybe it a good spot so you likely use their old fire pit as yours. You figure it was safe enough for someone else so why make a whole new one. If its a nice site you may not want to have everyone create new fire pits for fear of destroying the beauty of the campsite. Unfotunately the Seven site has several fire features.  All from the same person(s)?  Any of the fire pits found, or bone deposits, don't mean they were created or left by the same person(s).  Could others have used the cataway site before or after the partial skeleton was found?

But i like your thinking. Its going to be little nuggets or factoids that lead us to the final conclusion.  Not all of it will be found by science.  Proved by science maybe but the abstract and creative thinkers will open the doors on new ideas on this subject.
Respectfully Submitted;

Irv
 
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John Kada

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Re: Turtle remains
« Reply #2 on: September 05, 2011, 10:17:58 PM »

I found my colonists reference. In Bevington's journal (http://tighar.org/Projects/Earhart/Archives/Documents/Bevington_Diary.html), the October 13 entry states "A whale’s bones were clean and dry on the shore-side, and there were hundreds of marks where turtle had come up the beach to lay their eggs". Doesn't mean turtles aren't around other times of the year, of course.
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Martin X. Moleski, SJ

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Re: Turtle remains
« Reply #3 on: September 05, 2011, 10:30:41 PM »

The remains of a turtle were found along with the partial skeleton found by the settlers in 1940. I'm wondering if turtles would have been present at Nikumaroro all year round, or perhaps only part of the year (egg laying season?). If the latter, then then the turtle remains would suggest the time of year at which the castaway was making camp at the Seven site (I am assuming here that the castaway ate the turtle, and not the other way around...). If this angle hasn't already been looked into, it would be interesting discuss this point with a turtle expert, no?

"The Green Turtle (Chelonia mydas) was previously recorded as being indigenous to Nikumaroro (Garnett 1983)" (PIPA Report, Appendix F).

Wikipedia: Green sea turtle: "Green sea turtles migrate long distances between feeding sites and nesting sites; some swim more than 2,600 kilometers (1,600 mi) to reach their spawning grounds. Mature turtles often return to the exact beach from which they hatched. Females usually mate every two to four years. Males, on the other hand, visit the breeding areas every year, attempting to mate. Mating seasons vary between populations. For most C. mydas in the Caribbean, mating season is from June to September.  The French Guiana nesting subpopulation nests from March to June. In the tropics, green turtles nest throughout the year, although some subpopulations prefer particular times of the year. In Pakistan, Indian Ocean turtles nest year-round, but prefer the months of July to December.

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Were turtles seen on Niku during any of Tighar's expeditions?

Yes.
LTM,

           Marty
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John Kada

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Re: Turtle remains
« Reply #4 on: September 05, 2011, 11:01:12 PM »

Thanks Marty,

So it sounds like turtle season is year round on Nikumaroro, since Wikipedia says that 'in the tropics green turtles nest throughout the year'. But then that article also says that in two tropical locations, i.e. French Guiana and the Caribbean, there are definite, or at least preferred, nesting seasons, so I lean towards thinking from Wikipedia that sea turtles are year round visitors to Niku, but I still think it would be nice to get verification this from someplace outside of Wikipedia.  Not that they're ever wrong about anything, mind you.

What times of year were those Tighar expeditions where turtles seen? Maybe they were seen on every expedition?

I never thought I'd be spending any of my time writing posts about turtle nesting season...
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Martin X. Moleski, SJ

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Re: Turtle remains
« Reply #5 on: September 06, 2011, 06:31:13 AM »

So it sounds like turtle season is year round on Nikumaroro, since Wikipedia says that 'in the tropics green turtles nest throughout the year'. But then that article also says that in two tropical locations, i.e. French Guiana and the Caribbean, there are definite, or at least preferred, nesting seasons, so I lean towards thinking from Wikipedia that sea turtles are year round visitors to Niku, but I still think it would be nice to get verification this from someplace outside of Wikipedia.

My conclusion is that turtle behavior varies from place to place.

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What times of year were those Tighar expeditions where turtles seen? Maybe they were seen on every expedition?

I don't know.  If you search the website for the word "turtle," you will get 10 pages of results to browse. 
LTM,

           Marty
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Andrew M McKenna

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Re: Turtle remains
« Reply #6 on: September 06, 2011, 09:43:25 PM »

I think turtles are in the area year round, but nest more so, or even primarily in the fall.  I believe we saw turtles on all three trips that I've been out there, May-June (2010), July-Aug (2007), and Aug-Sept (2001), however, if memory serves there was far more evidence of nesting near the 7 site during the 2001 trip, ie later in the fall.  Last trip out there in May-June (2010) I think we saw some old remnants of nesting tracks, but nothing fresh like tracks of Aug-Sept (2001).

In 2001 while diving in the lagoon, we ran across some smaller "juvenile" turtles who I think use the lagoon as a safe harbor before moving out to sea, but the nesting seems to take place on the ocean side near the 7 site.

Andrew
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John Kada

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Re: Turtle remains
« Reply #7 on: September 06, 2011, 10:59:04 PM »

Thank you Andrew,

And your observations jibe with what I was able to find out  about seasonality from a 1975 paper by George Balazs (you can access it here: http://www.sil.si.edu/digitalcollections/atollresearchbulletin/ARB_RecordSingle.cfm?issue=184), cited in the Garnett reference given by Marty. And I think Bevington's diary also agrees with your observation that the 'Seven' end of the island is the turtle-end.

 Balazs says that on Canton nesting occurs 'during the entire year however the presence of larger numbers of animals during October and November indicates that a seasonal nesting cycle may also be present.' So, the turtle remains offer nothing strongly indicative about the time of year the castaway caught that turtle, but they do sort of, kind of, weakly hint at September-October-November...
« Last Edit: September 07, 2011, 12:08:38 AM by John Kada »
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John Kada

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Re: Turtle remains
« Reply #8 on: September 06, 2011, 11:18:48 PM »

I should add that I've emailed Dr. Balazs, who is a well respected turtle expert at the National Marine Fisheries Service in Hawaii. If there is anything more to add, I'll be sure to post an update.
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Chris Johnson

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Re: Turtle remains
« Reply #9 on: September 08, 2011, 05:26:52 AM »

Another more recent expedition also suggests activity all year round Atoll Research Bulletin issue 589
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John Kada

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Re: Turtle remains
« Reply #10 on: September 08, 2011, 10:45:35 PM »

Thanks for that Chris,

It is pretty clear from the all the information dug up in the last two days, ie. paper you found, Andrew's observations, the Balazs paper and Bevington's diary, that the turtle remains don't tell us anything about the time of year the castaway made camp. And to top it off, Dr. Balasz, the NOAA turtle expert, very kindly replied to my email today and his opinion is likewise. According to Dr. Balazs, juvenile turtles are typically present year round on islands such as Nikumaroro (as Andrew surmised--a turtle nursery in the lagoon...), and while breeding is seasonal, the breeding season is a long one (he said for many summer months).

Oh well, it was definitely worth nailing this down.
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Ric Gillespie

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Re: Turtle remains
« Reply #11 on: September 09, 2011, 05:39:35 AM »

Oh well, it was definitely worth nailing this down.

Yes, definitely.  Good work gentlemen.
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Chris Johnson

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Re: Turtle remains
« Reply #12 on: September 09, 2011, 06:22:39 AM »

I think turtles are in the area year round, but nest more so, or even primarily in the fall.  I believe we saw turtles on all three trips that I've been out there, May-June (2010), July-Aug (2007), and Aug-Sept (2001), however, if memory serves there was far more evidence of nesting near the 7 site during the 2001 trip, ie later in the fall.  Last trip out there in May-June (2010) I think we saw some old remnants of nesting tracks, but nothing fresh like tracks of Aug-Sept (2001).

In 2001 while diving in the lagoon, we ran across some smaller "juvenile" turtles who I think use the lagoon as a safe harbor before moving out to sea, but the nesting seems to take place on the ocean side near the 7 site.

Andrew

This seems to be a common trait in the Phoenix group with a fall in Turtle Population, possibly from the impact of Line fishing.  Lets hope PIPA helps the population to come back.
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