More Polls

Overnight had been clear.There was a slight frost on the screen as the instrument panel lit up - “beware of possible ice”.

I was travelling back to the hills today where I met up with Andy in the expectation of more finches and maybe a warbler or two; especially so since Andy’s ringing near his home on Friday produced 5 Meadow Pipits, a couple of Great-spotted Woodpeckers, a Tree Pipit, a Blackcap and a Willow Warbler. 

Tree Pipit

Try as we might we caught no Tree Pipits today nor did we catch a singing Blackcap, and one only of the 4 Willow Warblers around. So we made do with yet more Lesser Redpolls amongst the 19 birds of 5 species: 13 Lesser Redpoll, 3 Goldfinch, 1 Siskin, 1 Chaffinch, 1 Willow Warbler. 

Willow Warbler

Siskin

The very first Lesser Redpoll caught was already ringed but with ring number not of our own sequences. At number S295643 the record is now sent to the BTO who interrogate their data to discover the who, when and where. 

Just one Siskin today out of the eight or ten we saw and heard. At 8th April the species’ spring passage may be over. 

One of the Lesser Redpolls we caught had greyer tones than the other more typically brown and buff Lessers caught at the same time. The unwary might be tempted to call it a Common (Mealy) Redpoll but at this time of year and as a second year female the plumage is very worn by way of extensive whitish covert bars and fringes to the flight feathers. The bird was Lesser Redpoll size and “jizz” and we concluded it to be this species alone. Two images of the same bird below. The top one is taken in goodish sunny light, the second one in the shade of the car's hatchback.

Lesser Redpoll

Lesser Redpoll

Thankfully and not before time the Common Redpoll and Lesser Redpoll will be lumped back together as one species beginning in 1st January 2018 after the rather dodgy split into two species made in the year 2000.  I hope someone remembers to tell the birds before 1st January so that they can prepare for spring 2018, safe in the knowledge that it’s OK to begin breeding with the “other” species again. 

Are Redpolls Just One Species? March 2015.

"Mason and Taylor looked beyond the plumage into strands of the birds’ DNA in the most extensive look ever at the redpoll genome. Whereas previous genetic analyses of redpolls looked at just 11 regions of the genome (at most), Mason and Taylor examined 235,000 regions. (That impressive number is a testament to the exponential advances in DNA-sequencing technology, but the researchers are quick to note it’s still less than 1% of the total genome.)

In all, the duo compared DNA from 77 redpolls, including specimens from museums around the world, from the Museum of Vertebrates at Cornell University to the Natural History Museum of Geneva in Switzerland. They found no DNA variation that distinguishes Hoary Redpolls from Common Redpolls. Furthermore, another redpoll species found in Europe—the Lesser Redpoll—also had extremely similar DNA sequences. This extreme similarity among all the redpolls stands in marked contrast to studies of other groups of birds—such as Black-capped and Carolina Chickadees—which show differences at many regions of the genome.

In nature, one of the key differentiators among distinct species is assortative mating, that is, members of a group breeding with each other more often than they breed with members of another group. According to Mason, when it comes to Hoary, Common, and Lesser Redpolls, “There are no clear-cut genetic differences, what we would expect to see if assortative mating had been occurring for a long time.”

"The physical differences among redpolls are associated with patterns in their RNA, not their DNA. In other words, the variation in plumage and size is probably not a matter of genetic variation, but of genetic expression. It’s like how two humans might have the same gene for brown hair, but one person’s might be lighter than the other’s—that gene is being expressed differently.”

Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation, and expression of genes.

There’s a useful set of photographs of Lesser and Common Redpoll here.

On the way home via Garstang and the mosslands I saw my first Swallows of the year, a pair on wires close to farm buildings. Also, 3 different Kestrels and a pair of displaying Buzzards, one of them visiting last year’s nest.

Linking this post to Anni's Birding Blog.