Basic Instincts

As we approach another 'high pressure dome' of peak summer temperatures which follows a week of relatively cool, windy and sometimes wet conditions, housekeeping in the nest has reached feverish proportions. Both Syfaddan and Clogwyn keep up a steady retrieval of a variety of nest materials, from soft bedding to oversize sticks, which the pair have then set about arranging around the nest perimeter. The rapidly-developing chicks with their greater mobility make the need for extra fortifications ever more necessary hopefully helping to prevent any unforeseen accidents. On a couple of occasions we have even witnessed the chicks joining in this activity, pecking away at sticks and carrying twigs in their beaks. Rather than a wish to contribute to the fortifications in a meaningful manner this is most likely just instinct.

Chick with a stick

Of course, this hasn't interfered with the constant fish deliveries of some 4 or 5 each day. On 17 June Syfaddan was tracked from Llangors Lake where he had caught his fish.

Fish delivery

A recurring theme throughout this week of observations has been Clogwyn's continued incubation of the remaining egg. Many data entries record Clogwyn splitting her time between brooding and incubating. On a few occasions rolling the egg and “pushing the chicks aside” in order to incubate the egg.

Egg clearly visible in centre of nest

It is not uncommon for osprey females to continue brooding an unviable egg, sometimes for as long as over 60 days. This can be explained just from “instinct”. Powerful hormones triggered at egg-laying stage causes the female to lose belly feathers, 'a brood patch'. The physical sensation of the egg against the brood patch creates a neurological feedback loop locking her into a powerful parental state until the hormone levels eventually drop. Added to which eggs naturally hatch at different time intervals so the female is forced to keep incubating for long past the average deadline. And ospreys only lay one clutch of eggs per year so there is no evolutionary advantage to abandoning the egg incubation too early.

It will be interesting to see what effect the extreme heat of the forthcoming week will have on this situation. Meanwhile it is gratifying to witness the continuing good health of this lively family.