We Have Frog Spawn

Frog Spawn Spotted in the Pond

More than a week later than 2015 and a day later than what we recorded in 2013 but we have got the first batch of frog spawn in our office pond.  We noted increased frog activity about a week ago and in the warm weather yesterday afternoon we spotted a mating pair and suspected that the eggs would be laid in the night.  Sure enough, when the pond was examined this morning we noticed our first batch of frog spawn for the 2016 season.

A Close up of the Frog Spawn in the Office Pond

Frog spawn in the office pond (spring 2016).

Frog spawn in the office pond (spring 2016).

Picture Credit: Everything Dinosaur

The picture above shows a batch of frog spawn, the first of the season in our office pond.  A large Ramshorn snail is close by but this herbivore will pose no threat to the newly laid eggs.  The frog species is the Common Frog (Rana temporaria), these amphibians are no longer common, their numbers have declined dramatically in recent years and garden ponds are an important habitat for them.  Most gardeners welcome these unobtrusive creatures as they consume lots of garden pests such as slugs and beetles.

We suspect it will not be long before our second batch of frog spawn is laid.  We have noticed another breeding pair in the pond this afternoon.  It is likely that we will have a second batch of spawn in the morning.  Interestingly, the spawn has been laid in one of the deeper parts of the pond.  The office pond is only about two feet deep (sixty centimetres) and it has been cleaned out with a lot of the weed having been removed recently, however, in folklore, frogs laying their spawn deep means that we are in for a particularly dry spring.  We doubt the weather forecasting abilities of the frogs ourselves but we shall have to wait and see.

Mystery Tadpole in the Pond

A single large tadpole has been observed in the office pond.  This animal overwintered in the pond and has yet to develop legs.  We were surprised to see this tadpole, we were not aware that some tadpoles did not undergo metamorphosis in the summer months after hatching in the spring.  Some research led us to the website of the Freshwater Habitats Trust: Freshwater Habitats Trust – The Common Frog and in their highly informative article, it is stated that the overwintering phenomenon has been recognised but the reasons for adopting this strategy are not fully understood.  The web page did state that these tadpoles are in some way ahead of the game come the following spring and the decision about whether to follow this strategy appears to be made quite early on in the year.  We are not aware whether individual tadpoles are genetically predisposed to develop over two years or whether all Common Frog tadpoles could potentially do this.

Reference is made to an academic paper on this subject, namely: Larval over-wintering: plasticity in the timing of life-history events in the common frog P. T. Walsh, J. R. Downie, P. Monaghan, Journal of Zoology Volume 276, Issue 4, pages 394–401, December 2008.

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