On 16 March 2012 a rabid eastern red bat (Lasiurus borealis) was found attached to an evening bat (Nycticeius humeralis) in Randolph County, Arkansas, USA. This appears to be the first confirmed case of a rabid bat attacking a bat of another species.

On 16 March 2012, a man living near Pocahontas in Randolph County, Arkansas, USA, heard something squealing on the ground beside his truck. Thinking it was a mole, he reached down and grabbed it with his hand and was bitten. Believing he had grabbed the wrong end of the mole, he attempted to switch his hold to the other end of the animal, but was bitten again. At this point, he realized that he had picked up two bats, attached to one another.

The Arkansas Department of Health was notified and both bats were submitted for rabies diagnostic testing. They were identified as an adult female eastern red bat (Lasiurus borealis) and an adult female evening bat (Nycticeius humeralis). The red bat was determined to be rabid by detection of rabies virus antigens in the brain by the direct fluorescent antibody test. A brain tissue sample was sent to the Kansas State University Rabies Laboratory (Manhattan, Kansas, USA) where the virus was identified as the Lasiurus borealis 2 rabies virus variant (Streiker et al. 2010).

While rare, there are published accounts of interspecific aggression among bats. In 1946, Bishop (1947) captured a hoary bat (Lasiurus cinereus) grasping an eastern tri-colored bat (Perimyotis subflavus), and another apparent attack by a hoary bat on this species was documented by Krynak and Riebe (2013). Orr (1950) observed a hoary bat that appeared to be pursuing a smaller bat. Krynak and Riebe (2013) suggested that hoary bats may feed on other species of bats.

Another explanation for interspecific aggression is the presence of rabies virus in the attacking bat. Bell (1980) saw a hoary bat attack a silver-haired bat (Lasionycteris noctivagans), a Brazilian free-tailed bat (Tadarida brasiliensis), and a big brown bat (Eptesicus fuscus). After observing these attacks, a hoary bat was captured, and determined to be rabid. This bat was presumed, but could not be proven, to be the same one involved in the three observed attacks, based on the presence of fresh blood on its face and head.

Transmission of rabies virus from one bat species to another has been inferred by the presence of rabies viral lineages typically found in one bat species detected in another, and there is evidence of transmission of a Lasiurus borealis variant from the red bat to evening bats (Streicker et al. 2010). However, the transmission rate from red to evening bats was believed to be low; for every 100 rabid red bats, the virus was expected to be transmitted to only one to five evening bats.

Though incidents such as the one we document are not unexpected given known cross-species transmission of rabies virus, this does appear to be the first confirmed observation of a laboratory-confirmed rabid bat attacking a bat of another species.

Bell
GP
.
1980
.
A possible case of interspecific transmission of rabies in insectivorous bats
.
J Mamm
61
:
528
530
.
Bishop
SC
.
1947
.
Curious behavior of a hoary bat
.
J Mammal
28
:
293
294
.
Krynak
TJ
,
Riebe
JA
.
2013
.
An apparent attack on a tricolored bat (Perimyotis subflavus) by a hoary bat (Lasiurus cinereus) in northern Ohio
.
Bat Res News
54
:
1
2
.
Orr
RT
.
1950
.
Unusual behavior and occurrence of a hoary bat
.
J Mammal
31
:
456
457
.
Streicker
DG
,
Turmelle
AS
,
Vonhof
MJ
,
Kuzmin
IV
,
McCracken
GF
,
Rupprecht
CE
.
2010
.
Host phylogeny constrains cross-species emergence and establishment of rabies virus in bats
.
Science
329
:
676
679
.