Hello everyone! We have a little of  shorter blog this week (I think) due to the limited information about this species on the internet! How surprising, I know.

Also a PSA: As you read this blog, pretend you do not see 👀🙈if I write “grey” in one sentence and then “gray” in another (like sometimes the literal next sentence). I use the “e” and “a” interchangeably based on the vibes~~ (Yes, I know I can easily edit them, but it makes this blog qUiRky)

Another PSA: if you are ever curious about the species and search up “gray —” in the IUCN, you will not find anything because they use “grey —”.… I am understanding why scientific names are so important right now. 

Ok I digress. Enjoy! 

Species of The Week: Gray Bat 

Myotis grisescens 

The gray bat – feared, hated, and casually killed — was tumbling toward extinction in 1959. These cave-dwelling bats, which once filled the evening skies over much of eastern North America, were so vulnerable to human destruction that hundreds of thousands were being slaughtered in single acts. 

The creature once flourished in caves all over the southeastern United States, but due to human disturbance, gray bat populations declined severely during the early and mid-portion of the 20th century. 95% of gray bats now only roost in 11 caves. 

Are They Endangered? 

While researching this species, I was seeing a lot of conflicting answers of whether the Grey Bat is endangered or vulnerable. I am coming to the conclusion that they are no longer endangered (They are still going to be a part of this blog though because they deserve some love). According to the IUCN, in 2008 these bats were “Near Threatened” and then as of 2018 they are considered “Vulnerable” 

This is the IUCN’s explanation for their rating 

“This species is listed as Vulnerable; it has been considered Endangered by the U.S. Fish and Wildlife Service, but there are several recuperation programs for this species reaching at the moment few million individuals. Despite large population size and good recovery, the species is regarded as being vulnerable to potential massive mortality from white-nose syndrome. Considering a time period of three generations (30 years), including both past (12 years) and future (18 years), this species is likely to decline by more than 30% across its geographic range. The expansion of WNS in eastern North America is threatening several species, like Myotis grisescens, causing that the species may reach the criteria for Vulnerable, considering that previous to 1990’s the declining in the population was larger than 50%, and the current scenarios are not favourable for many of these populations.” 

Habitat 

With rare exceptions, gray bats live in caves year-round. During the winter gray bats hibernate in deep, vertical caves. In the summer, they roost in caves which are scattered along rivers. These caves are in limited areas of the southeastern United States.  

Fun Facts 

• The Gray Myotis is the largest of the Myotis species occurring in the eastern U.S.
• It is distinguished from all other bats within its range by its unicolored grayish brown dorsal fur. All other eastern bats have bi- or tri-colored fur on their backs. 
• Territories tend to be controlled by reproductive females. These females seem to claim the same territory year after year #girlpower 
• The bat’s wing membrane connects to its ankle instead of at the toe 
• Gray bats use caves differently at different times of the year. For example, populations of gray bats tend to cluster in caves known as hibernacula to prepare for winter hibernation. In contrast, their populations disperse during the spring to establish sexually segregated colonies. 
• After 37 years without a single documented gray bat within the state boundaries of Mississippi, on September 20, 2004, a male gray bat was discovered in Tishomingo County in northeastern Mississippi, 42 km south of the last known location of M. grisescens before their decline and disappearance within the state of Mississippi. 

Why are they in danger? 

Human Disturbance 

Gray bats are endangered largely because of their habit of living in very large numbers in only a few caves. As a result, they are extremely vulnerable to disturbance. Arousing bats while they are hibernating can cause them to use up a lot of energy, which lowers their energy reserves. If a bat runs out of reserves, it may leave the cave too soon and die. In June and July, when flightless young are present, human disturbance can lead to mortality as frightened females drop their young in the panic to flee from the intruder. 

Cave Commercialization and Improper Gating 

The commercialization of caves drives bats away. Any gating on the cave that prevents access or alters the air flow, temperature, humidity, and amount of light is harmful. 

This decline actually began with cave disturbance associated with saltpeter production during the Civil War. Some of the largest colonies were lost as a result of the cave commercialization. 

Habitat Loss or Degradation 

Habitat loss and degradation and contamination from pesticides also are considered a cause of decline. Natural flooding and impoundment of waterways has resulted in temporary impacts to some caves and the complete submersion and loss of other important cave sites. Even if the bats escape the flood, they have difficulty finding a new cave that is suitable. 

The use of forestry insecticides and crop pesticides in areas adjacent to riparian corridors where gray bats forage may reduce the prey base or kill bats that ingest contaminated insects. Some maternity and hibernating colonies are susceptible to human disturbance.

White-nose Syndrome

WNS killed roughly six million bats in 2014. It spread over two thousand kilometres within North America, and most of its impact is on eastern populations of bats, like Myotis grisescens. This disease is considered as one of the major threats to populations of this species.

What is being done? 

Listing 

The gray bat was added to the U.S. List of Endangered and Threatened Wildlife and Plants on April 28, 1976. 

Recovery Plan 

The Tennessee Valley Authority sponsored a recovery project that resulted in the protection of two critical maternity sites: the Hambrick and Nickajack caves in Tennessee. Blowing Wind Cave in northern Alabama, the most important summer cave known for gray bats, has been acquired by the U.S. Fish and Wildlife Service and a gate has been placed across the entrance. Fern Cave, the largest known gray bat hibernaculum, has also been purchased by the Fish and Wildlife Service and is being managed for protection of the bats. The U.S. Fish and Wildlife Service also has acquired and protects additional caves in Alabama.

To protect habitat, The Nature Conservancy has established six voluntary protection agreements with private landowners for gray bat maternity sites. The National Park Service restricts human access to six Gray Bat maternity caves on its lands and monitors them for possible disturbance. The Indiana Bat and Gray Bat Comprehensive Plan contains a detailed list of caves that have been protected or are currently being managed.

Habitat Protection 

A variety of government and private conservation agencies are all working to preserve grey bats and their caves. 

Cave protection efforts have led to recent population increases. By 1991, the range-wide population was stable and perhaps growing, apparently due to successful cave protection efforts.

Sources 

https://www.fws.gov/midwest/endangered/mammals/grbat_fc.html  

https://en.wikipedia.org/wiki/Gray_bat  

https://www.iucnredlist.org/species/14132/22051652  

And that’s it for this week!