Sunday, 24 February 2013

Are you looking at me?!

A large part of the Blackbird project involves re-sighting birds we have previously caught. On our most recent visit we noticed that the birds' behaviour to our attentions can be different to that compared to their behaviour toward other park users.

Even though a walker, cyclist, jogger or even dog walker would pass by a few metres from them, the birds would move away calmly with a few hops towards cover, re-emerging only a few seconds later. However,  on a few occassions when we focussed scopes or binoculars on them, despite being 10m or so away, the birds would move towards cover with much more urgency sometimes flying to the nearest hedge or up into a tree. Surely, being further away, we represent far less of a threat?
The answer may lay in the results of a recent study published in the journal Ethology. Clucas and colleagues looked at how American Crows (Corvus brachyrhynchos) varied the urgency of escape and flight intitiation distance to approaches by humans with varying degrees of eye contact and facial expression.

Although the facial expression (smiling or scowling, sadly they didn't test frustration) of an approaching human had no affect on the crows behaviour, the amount of eye contact did. Crows moved away sooner and with more urgency when the human was gazing directly at them compared to when they averted their gaze. Such a response may represent an adaptation to living in urban areas with the crows using this visual cue to gauge the intention of onlookers.

While other park users may pay little attention to the blackbirds, we are directly gazing at them when trying to read their ring numbers. Perhaps some of them perceive the lenses of our binoculars or scopes as eyes, exaggerating the "gaze affect"?

With a little fieldcraft and patience we did manage to re-sight A4, B6, B4, AB,  BK and BD, not to mention several unringed birds! A4 in particular seems completely oblivious to our attentions and at one point stopped in front of us before resuming feeding a few metres away.

Here's looking at you: Intially some blackbirds are wary when the binoculars
 are focused on them, while others carry on feeding as normal.

Clucas, B., Marzluff, J. M., Mackovjak, D., Palmquist, I. (2013), Do American Crows Pay Attention to Human Gaze and Facial Expressions?. Ethology. doi: 10.1111/eth.12064

Sunday, 17 February 2013

Five new birds!

Two early morning visits to the park on Friday and Saturday resulted in the addition of five new birds to the project; three males and two female. This brings our project total to 37 marked birds. Our target of 50 before April 30th should be achievable!

Friday's catch very much exemplifies our data set as a whole, with males out numbering females 2:1. Watching the birds may have provided part of the answer; the males seem to blunder and bluster about the park, showing off to rivals and generally being boisterous towards the each other, whereas the females keep very much to themselves.
The three birds from Friday's catch with their new colour rings.
After each catching session we took sometime to catch up with already ringed birds, managing to re-sight A4, AB, AH BC, BB, BD, BX and BK. The latter two seem to have established a territory together on the border of the Llandaff Allotments and the muddy paddock to the south. Although she was not seen carrying any away, BK was seen picking up potential nest material so nest building in the park is imminent if not already in progress. If you see colour-ringed blackbirds in (or out!) of the park then please do let us know. You can find out how to submit sightings here.
BX (above) seems to have set up territory with the similarly coded female BK

Sunday, 10 February 2013

The Cardiff Blackbird Project

The Cardiff Blackbird Project was established in April 2012 to examine the ecology, behaviour and demography of urban birds using the blackbird as a model. The blackbird has many traits that make it ideal as a model species. It is a common species, making for large data sets. It is a relatively large species, meaning it is easy to observe. Blackbirds also wide spread which allows comparison between populations in different habitats and geographical scales.  Currently the study site for the project is the northern part of Pontcanna Fields in the area which includes the allotments and Cardiff Riding School.

View Larger Map
The project is based around developing a long-term monitoring programme, contributing to the British Trust for Ornithology’s (BTO) ‘Retrapping Adults for Survival’ scheme, on which a number of more detailed research projects examining blackbird ecology in a suburban environment will be based. The success of these projects relies on having a large population of individually marked birds that can be followed throughout the year. Unique plastic colour rings are fitted so that individuals can be recognised through binoculars/telescope, avoiding the need to capture birds multiple times.
Close up of a female blackbird showing the metal BTO ring and her Cardiff Blackbird
Project colour ring. CJ was ringed in January 2013
If you see a colour ringed blackbird we'd love to hear about it. You find out how to you can submit sightings here.