The autumn bird migration is now in full swing. This month will bring a mass arrival of thrushes including migrant Blackbirds, Redwings, Fieldfares and Song Thrushes. It is a good idea to keep those feeders topped up during this month as this can attract the common migrants such as Brambling, Chaffinch, and Siskins. Slice and spear apple onto tree branches and you may be rewarded with a sighting of the fruit loving Waxwing and Blackcap. Keep an eye out for the UKs smallest bird, the Goldcrest, weighing it at a mere 6g! They are very distinctive with their yellow/gold strip down their head. They are insect eaters so will often be seen flitting amongst bushes catching small bugs and flies.
In Focus- Grey Seal Pups
Seems a strange time of year of any animal to decide to start giving birth, especially a marine animal just as the strong winds and storms start to blow through tossing up the sea. But there is method in the madness it seems, after a full summer of feasting on rich oily fish the mothers are in the best shape to give birth and suckle their young.
Grey seal pups are born on quiet, often remote beaches. The mothers haul themselves up onto the beach to give birth to their white fluffy young. The young will stay on this beach suckling their mother’s rich milk for around a month in which time they can put on 30kg in weight every 2 weeks. While the mothers are busy with their young, the male Grey Seals, who can weigh up to 300kg and grow to 2metres in length, stalk the beach fighting with other males to keep their territory and ‘harem’ of females. Once the females have finished suckling their young, they will mate with the dominant male before heading back to the sea leaving their pups alone on the beach. They will stay here for around another 2 weeks while they moult their white fluff and become brave enough to head out into the unpredictable winter seas.
Seals have been the subject of persecution in the past, especially the young Grey Seal pups whose white skins were highly priced. For this reason, seals are protected under the Marine (Scotland) Act 2010. This Act allowed Scottish Ministers powers to designate seal haul-out sites and protect them under the Protection of Seals (Designation of Haul-Out Sites) (Scotland) Order 2014. There are currently 47 designated seal haul-out sites in Shetland where it is an offence to intentionally or recklessly disturbed or harass seals.
Moth of the Month- Rosy Rustic
It is getting pretty late in the year for moths but with favourable weather and light winds the Rosy Rustic (Hydraecia micacea) is one of the few that will still be seen in the moth trap. They are a common resident flying from August-October. There size can vary greatly with females generally being larger and darker. The forewings are pointed and pinkish/brown with a rather velvety texture and darker margins in the centre. Adults will lay their eggs on the food plant (a low growing plant such as docks, potatoes, horse tails and yellow iris) before dying off. The eggs overwinter with the larva hatching in April, pupating underground without a cocoon before emerging as an adult in August.
In other news…
One of the more curious birds to arrive in October is the Great Grey Shrike (Lanius excubitor). They have grey backs, white underbellies and black and white markings on the wings and tail. Their most distinctive feature is their black mask and sharp hooked beak, giving them their nickname the ‘masked assassin’.
What makes these guys so interesting is their feeding habits. They are predatory, hunting small mammals, birds and lizards which they beat to death with their beaks. In Shetland they often hunt on Goldcrests which are passing through in high numbers at this time of year. They are lone hunters, sitting in wait on a vantage point such as a fence post. They can even imitate other birds calls to try and lure its prey closer. Now for the gruesome bit…once they have made a kill they will cache it for later by impaling it onto thorns and branches within a bush hidden from other predators.
As they are members of the passerine (songbird) family they have weak feet that are not designed for holding their prey, by impaling it onto a thorn or stick they can use this to secure the food while they use their beaks to pull it apart and devour it. So, if you happen to spot a bush adorned with small dead birds, you’ll know there is a Great Grey Shrike not far away!