Tagged badger

Research Byte: Post release survival of rehabilitated Eurasian badger cubs (Meles meles)

BIO  Adam Grogan

Adam is on staff at the RSPCA, IWRC Board Vice President, Vice Chair of The Mammal Society for Britain and Ireland, and on the Executive Committee of the British Council for Wildlife Rehabilitation (BWRC). He has experience surveying and radio-tracking a number of mammal species, including badgers (Meles meles), polecats (Mustela putorius), mink (Neovison vison), and water voles (Arvicola terrestris).

This post is a summary of the paper Adam presented at the 2014 BWRC Symposium.

The RSPCA has been interested in the survival of rehabilitated wildlife for over 10 years and has conducted a number of post-release projects on a variety of species. This is a brief summary of a radio tracking project investigating the survival of released juvenile badgers after being reared in captivity in artificial groups.

There is little known about rehabilitated badgers post release. Prior to 2013, the RSPCA radio tracked four groups of badgers and found poor survival rates for the fifteen animals collared. In all four groups, the badgers dispersed into different areas. Of the collared animals, nine were known to have died, either as a result of road mortality or failure to thrive. The radio signals were lost for the remaining animals except one, who was tracked for an excess of 200 days before she shed her collar. During this time, she had settled in to a local, wild badger group near to where her artificial badger group was released.

In early 2013, another group of rehabilitated badger cubs was ready for release. A site was offered from the West Surrey Badger Group (WSBG), which they had monitored extensively for a number of years. An artificial sett (or badger den) was also available and so with the enthusiastic support from the landowners, plans were drawn up to release the badgers in summer of 2013.

Juvenile badger (Meles meles) peaking out of an artificial sett. Photo credits: Jan Reen
Juvenile badger (Meles meles) peaking out of an artificial sett. Photo credits: Jan Reen

The WSBG examined the suitability of the site by checking the artificial sett and other setts close by for signs of use by resident badgers and found no visible signs of badger presence. An electric fence was installed around the artificial sett, putting in bowls for water and straw for bedding. The five cubs, 3 males and 2 females, were released into the sett in July 2013.

For the first two weeks, the WSBG conducted morning check visits and evening feeding visits. Unlike previous releases done in late autumn, these badgers were active right from the start and were out the first night. They had one encounter with the electric fence; dug a dung pit; polished up all the food that had been carefully scattered about and hidden under logs and stones; dug a new entrance directly into the back of the sett; and dragged in the straw that had been left outside for them.

A camera trap was set up to record activity occurring when observers weren’t present and found that all five badgers were exhibiting normal species-specific behavior. The electric fence was removed at the end of the 2-week settling-in period, which coincided with the arrival of a student from Swansea, Owen Bidder, who tracked the badgers at night for the next two weeks. The badgers were now free to explore their new environment.

Camera trap image of juvenile badgers (Meles meles) in a soft release enclosure.
Camera trap image of juvenile badgers (Meles meles) in a soft release enclosure.

After one night, only one badger was still sleeping in the artificial sett, while the other four were all in an empty sett 100 metres up the hill. Within days they had discovered another sett about 100 metres down the hill away from the artificial sett.

WSBG members continued to provide food and water during the summer although the amount offered was reduced as time went on. During the first two weeks, Owen reported increased exploration by the badgers, finding and exploiting more setts in the area. Early on, one badger lost his transmitter, which was found detached from the collar on a footpath almost a kilometer from the release site. Over several weeks the badgers discovered a total of 8 setts that the WSBG knew about in the area, as well as one sett that had not been recorded previously. All of these setts were empty as far as the WSBG knew.

While badgers did disperse, often two or three were found in one sett and on the odd occasion, all four. Some mating behavior was recorded on camera before the electric fence was removed so some alliances may have developed while they were still in the enclosure. They seem to regularly move from sett to sett, sometimes using a different sett each day. One badger moved off to the sett that was previously unknown to the WSBG, about a kilometer from the release site. Since he seemed to have selected a permanent home, the WSBG set up a camera and discovered that he was with an un-collared badger that they believe to be a local resident.

The badgers were tracked until late December 2013, which is when the transmitters all seemed to stop transmitting. The cameras have been deployed a few times since and have recorded some activity so now the RSPCA plans to use different equipment to see if the badgers are still present. All the badgers were fitted with microchips, so a feeding station with a chip reader and data logger will be set up to hopefully record the badgers coming and going.

What have we learnt?

  • After 18 months of captivity, rehabilitated badger cubs can quickly start a natural wild life.
  • When released they will find and utilize existing local setts.
  • They may disperse from the release groups or remain together.
  • They may integrate with local badgers provided there are only a few around.
  • It is well worth rehabilitating orphaned cubs.
  • It is a rewarding thing to do.