With reference to the article 'Chafers at RAF Mildenhall' (White Admiral 36:2324), 1 thought it would be relevant to expand on the subject and give some idea of the wildlife seen at the airfield during the course of the work carried out by the Bird Control Unit (BCU).
In July 1993 when the chafers were becoming more numerous due to the ban on insecticides at the air base, 1 was performing a routine patrol of the runway just before sunset when one small falcon was noted flying around. On closer examination this turned out to be a Hobby. These birds can be seen regularly traversing the airfield at a high rate of knots, pausing occasionally to chase a Skylark or to take a nap on the warm concrete.
On this occasion, late evening, the Hobby was flying differently, climbing and diving at a leisurely pace over the grassed areas. 1 drove closer and was amazed that the Hobby seemed totally unworried by my presence. At very close range, which was anything from 200 down to about 10 feet, the reason for the leisurely flight became apparent. Thousands of large chafers were filling the air and the Hobby was catching them. The bird's mode of flight was to increase its speed with a series of quick flaps, then pull up into a shallow, gliding climb of about 30 degrees and just as it was about to stall thrust out its feet to pluck a chafer from the air with great finesse. The Hobby would then nose over into a shallow, gliding dive, hold the chafer up to its beak, eat the usable parts and drop the inedible pieces to the ground. It would then accelerate and the whole beautiful process would begin again. Fortunately, there was little aircraft activity at the time and 1 spent about an hour watching the bird perform its version of a roller coaster ride. The following night the Hobby was back, and 1 managed to capture its manoeuvres on video film. Every clear day for the next two weeks the Hobby appeared just before sunset to feed on the insects. On one memorable occasion three Hobbys turned up. A Kestrel also tried to get in nn the act but was nowhere near as graceful as the wonderful little Hobbys.
Since 1993 the Hobby feeding frenzy has been an eagerly awaited annual event. 1997, however, brought additional aerial activity. The Hobby was back 'rollercoasting' over the end of the runway, but word seemed to have spread regarding the abundant food source as several bats (species unidentified) joined in the feast, wheeling about and taking and eating the insects on the wing. At one point the Hobby decided at a bat would make a better meal than a chafer and 1 was treated to a short but dazzling 'dogfight' between these two aerial experts.
RAF Mildenhall has seen its fair share of unusual birds. The airfield is made up of about 2000 acres of semi-improved calcareous grassland. It is bordered by conifer trees, small villages and farmland. The runway lies on the edge of the tens at one end and is close to Breckland at the other. The airfield itself does not provide much in the way of different habitats but many interesting species can be seen. The long grass programme in operation provides suitable habitat for breeding Skylarks. There are so many that attempts to count them fail miserably. Flocks of over 100 individuals overwinter here. Meadow Pipits are also prevalent, as are Wheatears. Several pairs have been seen nesting in disused rabbit holes. Pied Wagtails also visit occasionally. As expected, Rooks and Starlings are ubiquitous but even here we have the unusual: there are two albino Rooks. These birds have been visiting since 1992, so are at least five years old. Since 1996 an albino Jackdaw has been seen on many occasions.
Birds of prey noted include Sparrowhawks (with two nests identified just outside the perimeter fence), Kestrels and Hobbys. Merlins also put in a few appearances annually and a Hen Harrier has been seen quartering the airfield. Little and Barn owls have both been seen hunting on the flight line here. But rarest of all was the sighting of a Red Kite. The BCU first found this bird 10 miles from the airfield when looking for a lost Peregrine Falcon. To our surprise it turned out to be an individual from the release programme being carried out by English Nature. The radio transmitter attached to the Kite had by chance been set to exactly the same frequency as that attached to our lost Peregrine! Next day this bird was seen soaring over the runway. As well as Peregrines, the BCU at Mildenhall uses Lanners, Sakers, Buzzards, Harris Hawks and a Gyr/Lanner hybrid.
Wildfowl have also been seen: Mallards, Canada and Brent Geese. A domestic goose with clipped wings arrived one day but it is still unclear how it negotiated the 8 foot perimeter fence! Mute, Whooper and Bewick's swans have also visited. There is nothing worse than having to rugby tackle a dazed Mute Swan which has mistaken the runway for a river. It does, however, make one something of a hero with the base pilots!!!
Seagulls are of course often seen on airfields. Most airfields suffer from the presence of Black-headed gulls but at Mildenhall 90% of the birds are the much larger Lesser Black-backed gulls.
A variety of wading birds have been seen. Sanderlings, Curlews, Lapwings and Golden Plovers have all shown their faces along with Ringed and Little Ringed Plovers. Redshank have been hit by aircraft at night just outside the airfield perimeter.
Both Green and Lesser Spotted Woodpeckers have been noted feeding in the grass.
Swallows, House Martins, Sand Martins and Swifts can all be seen in the air over Mildenhall air base each summer.
Pigeons have increased in numbers ever since weedkiller use was banned here. Racing Pigeons fly across regularly. Wood Pigeons do the same. Collared, Stock and Turtle doves have all been seen at various times.
Mention must also be made of game birds. Pheasants and Red-legged Partridges attempt to nest on the airfield annually. The locally scarce Grey Partridge is often seen on the periphery of the airfield. On one occasion a Quail was seen. We also occasionally find Snipe hiding in the grass when flying the BCU falcons, and Woodcock can be seen most nights feeding' on the airfield grass areas a short distance from the off-base conifer trees.
More unusual birds have graced us with their presence. We have been visited by a Budgerigar and a Cockateel. Once a confused juvenile Heron was found "fishing" in the grass. Cormorants come by regularly to investigate the emergency water supply tanks. A Grey Plover was noted back in 1992, and for one week we were amazed to see a Wryneck which spent most of its time well camouflaged on a concrete post. In the summer months Nightjar have been seen feeding on moths around the airfield grass. The glow from their eyes when caught in the vehicle headlights for the first time is quite unnerving! Most unusual of all was the sight of a pair of Arctic Skuas which refused to vacate the runway one rainy day in August. Over the past few years we have noted no less than 78 separate bird species on the airfield! The species count would be higher if we considered birds seen and heard on the domestic side of the base. The 78 species referred to were all noted "air side". The 7811, a single Kittiwake, visited here early in the New Year.
Of the mammal life seen round the runway, rabbits are the most abundant with much of the runway lined with warrens. These animals seem to defy extensive control attempts and have also bounced back from severe myxomatosis outbreaks for the past three years. Two populations of black rabbits exist on the airfield perimeter and a beautiful silver/blue family live near the runway.
The airfield grass supports a large population of hares which are in decline elsewhere locally. One drive along the runway, when the grass is cut short, can reveal as many as 150 individuals!
Stoats and weasels are also seen. One memorable day a stoat which had caught a Skylark was seen being mugged by a Kestrel. The startled stoat dropped the Skylark and fled!
Flying mammals abound but are difficult to identify. Noctule, Pipistrelle and Whiskered bats have all been struck by aircraft. We also received some potentially rabid bats from Delaware aboard a C5 Galaxy. These were rapidly repatriated inside the empty aircraft which was not even permitted to upload it's cargo!
Returning to birds, the Swift merits special mention as this bird has been the focus of much attention at Mildenhall recently. These enigmatic little birds visit us from Africa for only four months of the year. Again, at Mildenhall they have increased dramatically since insecticides were banned. They defy all known bird control measures and can be found in their hundreds flying above the runway on 'bad' days. Some days the air is thick with these birds and then all of a sudden they are gone. When this happens a scan of the skies will reveal our little friend the Hobby cruising over the airfield. As soon as the Hobby departs the Swifts return in numbers.
Due to their very small size Swifts have not been considered a hazard here at Mildenhall. But, at a bird strike conference in 1996 the Israeli Air Force claimed that they had experienced two cases of these birds penetrating the wings of Hercules aircraft. Following this revelation, aircrews at Mildenhall were briefed on the subject. A dead Swift was taken along to show the pilots their new airborne hazard. But when informed about the habits of this remarkable bird many of the pilots voiced their disbelief. Some of the areas of contention are outline below.
Swifts have very short legs and long wings; if they land on the ground it is said that they cannot takeoff again. Their feet are designed for gripping so they can land on vertical walls. This issue is contentious but 1 have picked birds up from the runway which were apparently unable to take off. 1 can personally vouch for the strength of their grip!
Swifts are hosts to one of the most revolting blood sucking ectoparasites ever seen, in my opinion. 1 once picked a dead Swift up from the runway and took it to show the crew of the aircraft that had struck it. While 1 was holding it, one of these parasites ran onto my hand. It was about 1/3 of an inch long and a turquoise colour. It had a distinctly evil appearance. This particular Swift had two of them on its body. There is one reported case of a Swift dropping dead in mid air and falling to the ground. The person picking it up recorded 20 of these parasites on the unfortunate bird. As the parasites are unable to fly, drinking ones host dry does not seem to be best survival strategy! The parasite has been identified as a flightless louse fly, Genus Crataerina.
Swifts may stay airborne for several years at a time, sleeping and even mating on the wing. This claim is the one most often greeted with derision. Swifts mating whilst in a shallow glide have been seen over the airfield by the author on two occasions. Verifying the fact that Swifts sleep on the wing is more difficult. Some evidence comes from bird strikes. In the local villages on clear summer evenings large numbers of these birds can be observed screaming loudly, climbing higher and higher into the darkening sky. In early June 1997 an Air Force helicopter struck a bird at 300 feet during a night approach to a landing zone in Italy. The feathers were returned to me and were positively identified as coming from a Swift. Twice in early July 1997, C130s operating at low level over East Anglia returned to the airfield after striking birds at night. One was at 1000 feet and the other somewhere just below 2000 feet. Both of these definitely involved Swifts. One of the birds made a hole through the leading edge of the wing thus verifying the Israeli's claims.
Evidence also comes from the following account given by a French airman during the 1914-18 war: "We were tasked with a night-time reconnaissance mission which involved climbing to 15000 feet. The engine was then switched off and we glided downwards. At around 10000 feet and just above a layer of cloud we found ourselves in amongst numerous Swifts which seemed oblivious to our presence. It proved possible to lean out of the cockpit and pluck a couple of these birds from the air. The following day one bird was found stuck in our machine!" This has to be the first record of a bird strike involving a Swift and perhaps points strongly to the fact that they can sleep on the wing.
Ref: Lack, D. 1956. Swifts in a Tower. Methuen
Tim would be pleased to receive any records/observations/information on the night time activities of Swifts. (Ed)