Sunday, 1 July 2018

20180701 Kestrel on Little Tern chicks Blakeney Point


Kestrel appeared hovering briefly over west end of enclosures putting up all Little Terns, about 60 birds. 
Then flew low East along ridge whilst being mobbed.

Little Tern grabbing and striking Kestrel but fails to divert it from its attack run.

Kestrel took one hop on the ground then grabbed chick.
Appeared to be able to see chicks from low level flight.

Very small chick in left talons.

Male Kestrel then flew a short distance and landed within enclosure amongst sea-blight cover.
Over 7 Kestrel visits were recorded to the colony the previous day!?

Kestrel sitting on deck in shade of sea-blight and still being mobbed by Terns.
Bird seemed very bold and would not easily flush away from the colony.
Noted an abundance of Kestrel attacks in log over last two days and communicated with wardens.
The eastern enclosures colony has been wiped out.... by Kestrel??

From a very positive position as reported in last month's article the Little Tern colony on the Blakeney Spit has met with a major setback this season. From the 20th May Kestrels were recorded about the colony enclosure and their interest grew throughout June. Each visit by Kestrel  causes all the Little Terns on the shingle to rise up as one to meet with and mob it as it hovers and swoops over the colony. Unfortunately this does not deter  the raptor from its intended attack route and surveillance run low over the shingle ridge.
 By the 30th June over six visits daily were being witnessed by volunteers , during the monitored middle period alone, involving  two if not three Kestrels. The 1st of July saw the end of any nesting activity in the eastern enclosure and a few pairs desperately defending chicks left in the western enclosure. A male Kestrel now using the site as a drive through and sitting on the deck within the colony digesting its take away. A week later and all chick rearing activity had stopped with only two pairs of Little Tern feigning nesting rituals on empty scrapes.

It is widely known that  Avian predation is harder to manage than ground predation at tern colonies, as aerial access to the nest scrape has to be maintained , so allowing predatory birds in as well. In Britain, Little Terns nest in fairly mono-specific colonies so predation from other species sharing a location is minimal. Nest boxes have been tried for a number of species and the success has been mixed. Roseate Terns seem to take to these most readily, as on Coquet Island, but this is possibly because they prefer nesting in dense cover and nest boxes provide  a familiar alternative, unlike the minimal open scrape nesting of the Little Tern.

 It is also well documented that Individual avian predators that specialise in, and fixate on predation of terns often account for most losses at a tern colony. It may be that the most effective management is to target them specifically and Kestrels are top of the list in this respect. Supplementary feeding of Kestrels has been attempted with some effect in the past so as to provide an alternative prey source and decrease attacks on the tern colonies. It has been difficult to prove the effectiveness of the method and it may artificially maintain a high predator population producing a detrimental impact on the terns in future years. Kestrels have habituated to human efforts to deter them, static or active as I found with the male on the 1st July which would not flush away from the colony until the third attempt. They have also been recorded extracting chicks from funnelled shelters provided for protection but in this case chicks had not moved from their nest scrapes when the kestrels located them and attacked.

Lethal control of predators has frequently been considered but most conservation bodies shy away from this approach on humane grounds and to avoid negative publicity... This season the NT made every effort and went to great expense to create a secure site and also identified the rogue predators at the earliest possible juncture. Unfortunately and without due care and attention a timely managerial response, specifically targeted to the threat, was not forthcoming until after the predation event was over....??