Question Two
Proximate causes of endangerment are things that reduce the survival or reproductive rate of a species. One example is the thinning of eggshells (from DDT) that resulted in a reduction of reproductive success. Other examples would include a lack of nesting sites (from competition for them) and brood parasitism. Solving a proximate cause is like treating a symptom instead of a disease.
Ultimate causes are environmental threats that caused the endangerment in the first place. They are explanations that address the historical and evolutionary reasons why organisms respond as they do to their immediate environment. Examples are DDT (and other pesticides), habitat loss, and the introduction of an exotic species. Ultimate causes are often difficult to remove or solve and sometimes a species declines greatly before the cause can be solved.
Habitat loss (ultimate), pesticides (ultimate), predation (ultimate), and lack of roost sites (proximate) can threaten bat populations (Bat Conservation International 1991). In general, availability of roosting sites (proximate) rather than food availability, predation, or other factors is believed to be the primary limitation in the distribution and abundance of many bat species (Fenton 1970, Fenton and Barclay 1980, Humphrey 1975, Kunz 1982). The decline of the Hawaiian hoary bat is probably due primarily to the reduction of tree cover, which is an ultimate cause (Tomich 1986b, Nowak 1994). This reduction of tree cover also may lead to a loss of roost sites, which is a proximate cause, and could affect the reproductive success of the bat (NatureServe 2003).
Because the hoary bat appears to occupy principally forested lands, the loss of populations is attributed to reduction of tree cover. For example, it was documented that bat populations used to exist on the island of Oahu in large numbers. However, they have decreased significantly because of deforestation that occurred in the early 19th century. Observations and specimen records indicate that bats are now absent from some of their historically occupied range (Tomich 1986b, USFWS 2003). The tree cover is needed because they use the shelter of trees for protection against wind, sun, and rain. They also go into a state of daily torpor in them for energy conservation (Baldwin 1950, Kramer 1971, Tomich 1969, Tomich 1974, Tomich 1986a, Tomich 1986b).
Pesticides may also have an indirect effect on the bat population by reducing or otherwise altering prey populations. It may have even directly affected them through contamination because at least two federally endangered insectivorous bat species have had population decreases due to pesticide ingestion (Clark et al. 1978). Nonnative insect introduction could have also changed the availability of native prey species. On the positive side, though, predation is not currently a threat to the populations of the Hawaiian Hoary Bat (Shump and Shump 1982).
Human-made structures and human-caused conditions in the environment (an ultimate cause) exert a "predation pressure" on the Hawaiian hoary bat. This is indicated by the following examples: a bat impaled on barbed wire fence; a bat with a broken wing beneath guy wires; a bat that struck a wall and fell; and a bat that was stung on its lip by an alien Polistes wasp that was incapacitated. Such hazards will continue to exist within the habitat of the bat if something is not done to remedy them (Kepler and Scott 1983, Tomich 1986b).
Question Three
Currently there are no management activities underway for the Hawaiian hoary bat. There are many different activities that could address the various proximate and ultimate threats affecting the species.
The availability of roost sites (a proximate threat) is key to the survival of bats. Hawaiian hoary bat roosts could be found by mist-netting and attaching radio transmitters to bats because it will allow the bats to be followed to their specific roosting locations (Jacobs 1993, Mattson et al. 1996). Habitat loss (ultimate), especially the loss of roosting habitat, presents possibly the biggest threat to this subspecies. After the specific roosting sites are identified, they should be protected from degradation and disturbance. This could possibly include fencing of the units to protect them from domestic and feral ungulate and also the development of conservation agreements designed to restrict development activities and preserve the habitats. Restoration of native habitat could also be done to help solve the problem of habitat loss (USFWS 1998).
Predation (an ultimate threat) could also be a threat to this bat because it is vulnerable to cats, rats, the introduced common barn-owl, the native short-eared owl, and the native Hawaiian hawk. The mammalian predators could be controlled around the roosting sites by using live traps, snap traps, and rodenticides. Methods to control the bird predators would also have to be developed, but they would have to be implemented carefully because the Hawaiian hawk is an endangered species (USFWS 1998).
The ultimate pesticide threat could also be combated. If they are found to affect the bat subspecies, then they could be mitigated through techniques coordinated by the Hawaii Department of Agriculture, U.S. Department of Agriculture, and Environmental Protection Agency (USFWS 1998).
Some of the human-caused problems could also be solved. A public education program could be instituted to inform the residents of the needs of the bat, and an informed public may also be more interested in the conservation of the Hawaiian hoary bat. The educational program could inform the public of the benefits of having the bat in the Hawaii.
Question Four
The recovery goals for this species, as listed in the Recovery Plan, are as follows:
1. Conduct research essential to conservation of the subspecies.
1.1. Develop standardized survey and monitoring protocols to determine bat abundance and distribution on the island of Hawaii.
1.2. Implement survey and monitoring programs to determine Hawaiian hoary bat abundance and distribution on Hawaii, Kauai, and Maui.
1.3. Determine specific roosting habitat associations.
1.4. Determine annual natural history cycle.
1.5. Determine food habits on the island of Hawaii.
1.6. Conduct research on other islands.
2. Protect and manage current populations and identify and manage threats.
2.1. Identify and assess threats.
2.2. Control and manage threats.
2.2.1. Protect key roosting and foraging areas.
2.2.2. Control predators
2.2.3. Reduce the effects of pesticides, if needed.
2.2.4. Minimize other threats, as appropriate.
3. Conduct a public education program.
4. Evaluate the progress of recovery and revise recovery criteria as necessary.
I believe that these recovery goals are well conceived. They cover all needed aspects of recovery efforts, including further research and monitoring and managing the threats inherent to this species.
A population viability analysis was not performed for this animal because further research is needed. Intensive surveys and studies of population biology would determine the regional population size, would identify population concentrations (including roosting sites) and essential habitat, and would yield information required to identify recovery needs.
An empirical analysis based on observed populations would be beneficial. It would show whether the species has a chance of persistence or whether the species is going to become extinct. This would tell us whether or not to even create recovery goals for the animal because if there is a 100 percent chance of extinction, then the species would be a lost cause.
A theoretical analysis based on the population genetics of the animal would also be valuable. Then, managers could try to avoid inbreeding for a given population size. This would be important for the Hawaiian hoary bat since there is a small population of them, and inbreeding is a concern.
Simulation models based on ecological factors could also be done. This could show important data about how the three forms of stochasticity affect the animal. Then, recovery goals could be made based on how the different forms of stochasticity influence this species.
Question Five
There are numerous factors that can threaten the persistence of a small, endangered population. Inbreeding and random genetic drift can lead to the loss of genetic variability, which can lead to a reduction in individual fitness and population adaptability. This, in turn, can result in lower reproduction and/or higher mortality, and the final outcome of all of this is an even smaller population. Thus it can be somewhat of a continuous downward spiral.
The primary threats to small populations are usually chance events and fluctuations in normal processes. Demographic stochasticity, environmental stochasticity and catastrophes, and genetic stochasticity can hit a small population very hard (Wilson and Perlman 2000).
Some examples of demographic stochasticity are uneven sex ratios, a high death rate, or a low birth rate. All of these can drastically reduce the size of a small population, but uneven sex ratios are of specific concern. The Hawaiian hoary bat has a sex ratio of 3 females: 1 male (Tomich 1986b). This can harm the reproductive success of the bat if there are not enough males to impregnate all of the females.
Examples of environmental stochasticity include random changes in habitat, predation, competition, parasitism, and disease. Normal fluctuations in mortality rates from these occurrences create a major threat to small populations, whereas large populations can often easily survive them. For example, if a predator population dramatically increases, a small prey population may be wiped out before the predator population reaches normal levels (Wilson and Perlman 2000). The Hawaiian hoary bat has experienced habitat losses, and if they continue the species may be wiped out because it is a small population.
Catastrophes can include things like volcanic eruptions, major fires, floods, droughts, and other disturbances. These are extreme causes of environmental stochasticity. These events occur very rarely, but they can extirpate small populations. Many of these disasters could wipe out the Hawaiian hoary bat. For example, it lives in areas with volcanoes, so a volcanic eruption could affect the animal.
Genetic stochasticity can also be harmful to small populations. It can lead to inbreeding, which may be very detrimental. The loss of genetic diversity may reduce a population’s ability to respond to environmental changes or fluctuations. And, if all of the individuals have the same genetic make-up, then they would all be vulnerable to the same threats (Wilson and Perlman 2000). This could also apply to the Hawaiian hoary bat since it is a small, isolated population that is vulnerable to genetic stochasticity.
Question Six
The Environmental Protection Agency (EPA) considers many factors for listing a species as nationally endangered or threatened in the United States. The magnitude of the threat to the organism is looked at by seeing how many are left in the wild. The immediacy of the threat is also taken into account by guessing how soon it will go extinct if it is unprotected. Its taxonomic distinctness is all considered based on how unique the species is. The benefits to other species are also determined. This can be determined if it is something like an umbrella species where if this species is protected, a lot of species will be protected. The ecological role that the species has is also important, such as if it is a keystone or indicator species. And finally, the species status is established by whether it is a full species, subspecies or a distinct population.
If a species is then considered endangered or threatened, many steps can be taken to protect it. The “taking” (defined as to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or attempt to engage in any such conduct that would harm the species, including the degradation of its habitat) of the organism is prohibited. Government agencies are also prohibited from engaging in any actions that would harm the species or its habitat. And, critical habitat (areas on which are found those physical or biological features essential to the conservation of the species and which may require special management consideration or protection) can be designated for the species.
The Hawaiian hoary bat is considered endangered in the United States. And, I believe this is reasonable because the numbers of the species in the wild has been reduced from that of historic times, it is an indicator specials, and it may even be its own full species according to some studies.
IUCN (The Would Conservation Union) creates the Red List of Threatened Species by assessing the conservation status of species, subspecies, varieties and distinct populations globally. Then, once the risk of extinction is determined, the IUCN Red List catalogues and highlights taxa that are facing global extinction (listed as Critically Endangered, Endangered, or Vulnerable), taxa that are Extinct or Extinct in the Wild, taxa that there is insufficient information for and cannot be evaluated (Data Deficient), and taxa that are close to meeting threatened thresholds or that would be threatened if current conservation programs were underway (Near Threatened). These species are highlighted in order to promote their conservation (IUCN 2003).
The criteria evaluated are the following: population size, geographic range, number of mature individuals, rate of extinction, and amount of available data. Currently, the Hawaiian hoary bat is not on the IUCN Red List. I believe that it should be considered data deficient because there is not enough information to accurately evaluate it would these criteria, but it is likely that if more research were to be conducted, then the bat could be listed as threatened.
