The annual cycle of reptile activity for most species in the UK has one main inactivity period through the winter (From late October through to March). Hibernation for reptiles is known as brumation. Brumation is triggered by the lack of sunlight and falling daytime temperatures.
August is an anomaly in the annual reptile cycle [see info graph below] as activity levels fall. Record levels of rainfall during August 2015 will have made activity levels lower than ever as reptiles also stay in refuge during wet conditions on a more diurnal (daily) timescale.
The reason for the absence of reptiles during August is partly down to the birth and hatching of young. Many of the mini-reptiles joining the fray in the UK are slow worms (Anguis fragilis). The birth process takes up much of their time in August before the new life is finally born late in the month. Slow worms are born in an egg membrane but this doesn’t last long as the membrane breaks soon after birth (known as an ovi-viviparous birth type). Although well developed in terms of features, the young slow worms can be less than 1cm in length.
Another reptile found in the UK is the Viviparous Lizard (Zootoca vivipoa). They, unlike slow worms, give birth to live young making them viviparous – yes it is in their name! They are different to their relative the slow worm as they tend to give birth in late July and the lizard young are much bigger at around 4cm in length.
The grass snake (Natrix natrix) found in much of England and Wales lays eggs in June or July; the female then incubates the eggs until August or September when they hatch. This is an obvious explanation for the reduced activity in reptiles such as the grass snake. After they hatch the young are instantly independent.