David White, visitor experience officer at RSPB Lakenheath Fen, tells us about the tree that provides a great food source for birds
I will freely admit that when I started working at RSPB Lakenheath Fen nine years ago, I didn’t know much about trees. Although I wouldn’t call myself an expert nowadays, I certainly know a lot more about them now! When I think about February, one species of tree in particular comes to mind, the alder tree. I will therefore dedicate the rest of this article to this wetland loving species.
Alder trees tend to grow near water. The best way to identify them is by their distinctive brown nut-like cones, which frequently fall to the ground. Another useful way of identifying alder trees is by their catkins. Male catkins are long, yellowish and hang off of the trees. Although they can be seen as early as January, they tend to become more widespread from February onwards. They are therefore seen as one of the first signs of spring and bring joy to my heart.
We have some alder trees between our visitor centre and the pond the centre overlooks. They not only offer perching places for our local birds to make a dash to the bird feeders, they are a very valuable food source in themselves. Alder cones are particularly popular with several members of the finch family, including some species that you would have to be lucky to see in your garden. These especially include siskins and redpolls.
Male siskins are striking green and black birds with small beaks. Females are basically duller versions of the males. As their name suggests, male redpolls have red ‘polls’ or caps. These tiny little finches are barely larger than blue tits and hang off alder branches like a blue tit hangs of a bird feeder.
As well as being the best place on the reserve to see siskins and redpolls, the alder trees behind the visitor centre have been patronised by several scarcer species over the years. There are sometimes bramblings, another species of finch that winters in Britain feeding in them. One Christmas, there was a flock of 40 punk-rocker-like waxwings perching in them, inbetween fluttering down to a nearby guelder rose bush to gorge themselves on berries!
There are also some more alder trees around the Brandon Fen family trail. These are interspersed with similar sounding elder bushes. These bushes are more famous for their flowers, which appear from May onwards, and their distinctive black berries from August onwards. However, as they have hollow stems, they provide a valuable winter home for some of our local invertebrates. It is nice to see the two species together, as they offer a useful introduction to trees and shrubs to our reserve visitors.
Although, as usual, I have barely scratched the surface with this subject. However, I hope you have enjoyed it nonetheless. Please visit rspb.org.uk/lakenheathfen for more information about the reserve. We hope to see you soon!