Behaviour and Ecology Working Group

Report from the Behaviour & Ecology Working Group

Obviously behaviour and ecology continue to be a major theme in relation to bird hazard management and I think one of the emerging themes of this meeting was that behaviour is a very important factor whether or not a bird strike takes place. On the ecological front obviously climate change is an emerging theme and the ecological and behavioural sciences meet in, for example, the description of overflying behaviour, population dynamics, the behaviour and populations of birds in the vicinity of aerodromes and now the ready availability of radar to look at the pattern of overflying at night. So, what is emerging is a 3D picture, in cases of civil airports, of the numbers of birds over the runway, what they are doing on the runway, when they are there and so forth. In a way, a new picture is emerging and new possibilities are going to come from this.

In relation to climate change, I think it’s fair to say that there are a few people who do not accept that it is taking place, what direction it’s going is not that easy to determine because there is quite a bit of fluctuation. What it does appear to have an effect on is the mix of species in and around airfields and therefore the mix of species that are likely to be struck and also on the length of the breeding seasons and perhaps on different patterns of population dynamic behaviour between multi and single brooded species. We know for a fact that the wood pigeon in Ireland is being struck earlier, perhaps a month or six weeks earlier than it has been in the nineties and this is an important problem because that bird species is increasing. I believe due to the fact that the vegetation growing season is changing and the amount of vegetation is increasing, this is a theme that emerged from informal discussions with many people at European Airports, but it is not getting to the surface and we need some kind of concentration on making sure that people are monitoring these things.

Another interesting theme was the ultra low frequency sound work that was done by CSL and the fact that there is the possibility of developing an inaudible distress call system and that I think is something for the future.

In relation to avoidance behaviour, there is no question that birds avoid aircraft and that the aircraft is something that scares them very, very clearly. In fact it is the most effective scaring method of all because the aircraft has another signal, the bird knows if it gets near the aircraft it will be killed so they deliberately and most obviously avoid aircraft.

A theme that came up at Warsaw was largely due to Paul Eschenfelder asking the question “What do aircraft do in the air when it meets a flock of birds in the air?” and Richard Dolbeer presented a very interesting poster on this in Baltimore and to summarise it very briefly, there are data which I think amounted to about 600 records, something like that, showed that above 500 feet when an aircraft meets a flock of birds most of the birds will dive and the logical extrapolation is that the aircraft should go up rather than going down to avoid the flock. Below 500 feet the picture is less clear, some birds go down but it is less clear. This is an important field as well and we did mention it in Warsaw to gather informal observations from pilots about what happens when they encounter a flock of birds at different altitudes and the paper by Richard Dolbeer at Baltimore was a very important paper.

Using an analysis of injury I think we are starting to see certain patterns emerging as well. The pattern of injury in bird strikes is serious damage to the ventral surface and incidentally it is important to point out that the bird may look perfect but when you do the necessary dissection what you’ve got inside is a very, very severe series of traumatic injuries. The important thing to bear in mind is that the bird may look perfect and an important thing to check is the humorous and the radius, in particular the humorous. You will find in the upper bone of the arm that these are frequently broken but you may not see that unless you actually palpate the humorous to find out that they have been broken. People mention owls in particular, they may look perfect when they have been hit by an aircraft but when you do the necessary dissections you will find that both of the humouri have been broken and that the keel has been smashed in and the liver and spleen etc are seriously damaged. Although there may be no detectable difference at present between the motor car and bird strike injuries I think it is something that we are going to continue to pursue using more advanced statistics to separate these things out.

In relation to the overflying of runways this again is a methodology that has now become clarified and I know that some airports are interested in taking this theme up. One advance that the Dublin team put out in Gavin Fennessy’s paper is that the time over the runway is important – not the speed of crossing the runway – and that ties in with foraging behaviour of birds including foraging on the runway and the vigilance behaviour, how vigilant they are in the face of an aircraft coming up to them, while in the case of crows in particular ‘cashing behaviour’ – where they are hiding food in the grasslands along the margins of runways. We know for example that kestrels have very low vigilance for aircraft and they can keep hovering until it’s too late. Similarly we have found with black-headed gulls that if there are earthworms on the runway, they will fly down the runway but not land and their head is in vertical mode looking straight down at the material and that seems to reduce their capacity to detect and avoid aircraft.

In relation to change, we would like to see more co-operation between airports and population dynamics, on the timing of strikes, whether there has been a change, what the species mixes are, etc. This is basic ecology but it is important and it is important that we need to stress the changes taking place. Some incidental points that came up that are very interesting is that Mr. Lykos from Greece made a very important point during his paper that shooting near an airfield can disturb birds across the runway and I think that is something that people need to be very aware of. We had a situation in Dublin on one occasion where a flock of 2000 gulls was disturbed by a shooter and they all came across the active runway in a space of a few minutes so hunting and shooting near the airfield can actually cause hazards. The second thing is helicopters – Bruno Bruderer is working in Switzerland on disturbance by aircraft on waterfowl -were the most significant aircraft in terms of disturbance. Likewise, helicopters near the active runway are parallel to it outside the airfield and can disturb birds over the runway. I thought Dr. Bahat’s paper from Israel on a nicely designed study showed that behaviour can be used to enhance conservation, which was an excellent, simple, very effective piece of work.

Lastly I would just like to say that the fieldwork should continue, we would like to co-operate with anybody who is interested. There is a momentum now for work on behaviour in the field and then in the lab the iron vision work should continue. They have recently shown for example that crows do not possess ultra violet light receptors but possess enhanced vision in the violet part of the spectrum. These are interesting findings and they may have some significance. Likewise, some very interesting work has shown that olfaction is important; smell appears to be more important than we knew before. Taste aversion and the entophyte work, which was announced in Baltimore, I think may be very important.

Lastly in the case of the laser system, it is a behavioural question ultimately as to how effective it is.

Those are the themes we will be looking at in the future