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Glesni Lays an Egg!

Posted: Thursday 23rd May 2013 by Emyr MWT

Dyfi Osprey Monty and GlesniDyfi Osprey Monty and Glesni


Glesni has laid an egg. Her first ever egg.

On May 22nd at 17:18 and 40 seconds, she stood up and turned around for the umpteenth time that day and looked down. Only this time, and for the first time, there really was something there.

Here is that magical moment when Glesni sees the egg she has just laid for the very first time

Dyfi Osprey Glesni first egg

Just as many observers were resigning themselves to not having eggs this year, Monty and Glesni defied all the odds. But what were the odds? How odd is it that an osprey lays her first egg during the fourth week in May?

We know that first time breeders (Glesni) and new pair bonds take longer than usual. At least two weeks. Glesni returned to the Dyfi on 30th April this year, but was not accepted by Monty (he had other girlfriends at the time) for another three days, May 3rd. So that gives us a pair bonding time of 19 days and a bit. Not uncommon in-itself, but considering that this pair did not get it together until May anyway, it makes it pretty late to start laying eggs if you're an osprey in the UK.

Natural selection gives most birds an invisible cut-off point. It makes sense - osprey chicks on Christmas day with minus temperatures, five hours of daylight each day and frozen lakes? Not good. This glass ceiling for ospreys is around about mid May for eggs, but if conditions are optimal (good pair bonding, no disturbance, food availability, no freak weather events and so on..) this mid-May rule of thumb can sometimes be pushed forward. We saw this only last year with Black 80 and his mate, a Glaslyn 2006 male, in Threave, Scotland who also produced eggs at the end of May.

Pair bonding took 19 days from first mating to first egg. Jump on lad..
Dyfi Osprey Monty and glesnG

What was fascinating about Monty and Glesni this year was observing all the behaviours you would associate with imminent egg/chicks arriving. The incubation by both birds (incubation of no eggs that is!), the shuffling around, the fidgeting, the mating, leaving fish in the nest, the scraping out of the egg cup, bringing soft nesting material to the nest - the list goes on. These behaviours looked so strong, so indicative of egg laying, how could Glesni not lay eggs? The only thing that was counting against them was time, and as we got in to May the 20's it did start to look as these behaviours were a dry-run of things to come next year.

Here is a video of some of these behaviours leading up to and including Glesni laying her first egg. Remember that amazing video from 2011 of Nora 'practising' to feed her newly hatched chick (Einion) at the side of the nest? I said at the time it was one of those moments that you never forget - witnessing a very rare and special moment in an animal's life that may only happen once or twice. Well, it seems that this type of 'vacuum behaviour' is not as uncommon as we first thought. Look at Glesni, a full five days before even laying an egg, let alone having a chick hatched. Incredible.

(watch in HD for best results)

The osprey nest cameras continue to teach us more about these remarkable birds of prey. Researchers just a few years ago would have reported Glesni, and Monty, incubating an egg several days before an egg was actually produced, looking as they had to, from a ground level position probably a good 200 yards away. Older osprey records often show very long incubation times - 43, 44, 45 days (average is around 37 days). Did these really happen or were the birds behaving in a similar way to Monty and Glesni and giving the impression to the observer they were incubating eggs several days before they actually were? With the best telescope they could afford and all the devotion in the world, these early researchers could only document what they saw and guess the rest. Fascinating stuff.

Monty incubating an egg (ahem) three days before there was an egg
Dyfi Osprey Monty Incubating

So, good news so far. When could we expect another egg? Ospreys tend to lay three eggs (occasionally two or four) at three day intervals, so May 25th and 28th would be good estimates. But will the fact that they are so late in to the breeding season already have a say in this? Who knows, time will tell.

Update:  Egg No 2 laid at 19:06 on May 25th. Thats 3 days and 1¾ hours after the first.

It's a known fact that ospreys (and many birds actually) that tend to lay later in the egg laying window, tend to have reduced productivity (chicks) rates. We can guess the reasons for this.. more predation pressure (goshawks for example trying to feed their own families), soaring hot temperatures (remember them?) that are chick killers, autumn storms during late migration in October. It's early days and we shouldn't count our ospreys just yet before they hatch (or laid!). Glesni and Monty will need more luck than usual this year, particularly from the weather. If ever we need just an average weather summer, this is it. Not too cold, too hot, too windy, too rainy, just average. A Goldilocks summer please.

June 9th 2012. Not this year thank you.
Dyfi Osprey weather 2012

As many volunteers around the country are just getting their lives back after long night shifts in cramped cold hides, the night surveillance and the matchstick eyes are only just beginning here at the Dyfi. There are still those individuals that will attempt to illegally steal the eggs of rare birds. Only this week an egg collector was thwarted by a canoeist at Threave Castle in Scotland where Black 80 is breeding. Good on him/her. We start our 24 hour surveillance as other ospreys in the UK are hatching - the first chick at the Glaslyn was already nine days old when Glesni laid her first egg last night - that's how late they are!

So there we are, what a saga again this year. Mind you, we do have the best scriptwriter in the world - nature. A blog I thought I wouldn't be writing this year after Nora not returning, plus Monty's problems with all his different women throughout April. A blog also with absolutely no egg puns or jokes (eggciting.... this, eggspectant... that. What nonsense). No, we are much more scientific and serious here at Montgomeryshire Wildlife Trust to have to resort to cheap egg jokes.

If anybody wants me today, albumin the office.

Dyfi Osprey Monty and Glesni


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