Small Kauai Thrush (the Puaiohi)

Small Kaua'i Thrush

also known as the Puaiohipost by Amy Rutty

photo: Lucas Behnke

PUAIOHI QUICK FACTS:

• There are 500 individuals remaining (as of 2010). In 2006, this number was 300. Fortunately, the population trend is considered "increasing."
• The Puaiohi was listed as "endangered" federally on March 11, 1967 and in the state of Hawaii on March 22, 1982.
• Recovery priority LEVEL 2 - indicating an urgency in recovering the species. 
• The IUCN (International Union for the Conservation of Nature) views the Puaiohi as "critically endangered."

ECOLOGY:

DESCRIPTION:

• The Puaiohi is fairly nondescript as far as looks. Our little friend (who measures in at 16.5-17.8 centimeters and weights only 27-42 ounces) is olive brown on the majority of his or her body and gray on its throat, belly and under-tail. Their dark eyes stand out against a white ring, and its long, thin legs stand out compared to its short tail. 
• There is little variation in appearance between males and females. Juvenile Puaiohi (as shown below) have speckled feathers. 

LIFE HISTORY:

photo: Lucas Behnke

• Puaiohi are on the r-selected end of the life history spectrum. This means that they have shorter lifespans, reproduce frequently, and have more than one offspring at a time. 
• NESTING: Puaiohi females alone build their nests in cavities and along ledges, strategically hidden by vegetation. Nesting season begins in March and continues until mid-September, however the primary nesting season is April through June. After the female Puaiohi spends one to seven days building her nest, there is an eight to ten day period before the first egg is laid. From then, it is 13 to 15 days before the first egg hatches. 
• CLUTCH SIZE: The Puaiohi's clutch size averages around 2 eggs. Until the baby birds fledge (leave the nest), the female is the primary caregiver and provider. After fledging, the male assumes responsibility. 
• RENESTING: Female Puaiohis frequently attempt to nest a second time during mating season with fairly high success. This propensity to renest, in combination with the long breeding season and relatively high rate of nesting success means that the Puaiohi has relatively hight reproductive success.

source: 2006 Revised Recovery Plan for Hawaiian Forest Birds

HABITAT / LIFE REQUIREMENTS

• The Puaiohi is endemic to a small range on the Hawaiian Island of Kaua'i, in what is now the Alaka'i Wilderness Preserve.
• They are found only in 32 square kilometers (12.35 square miles) of forested ravines between 1000 and 1500 meters (3280 - 4900 feet) above sea level. 
• Their ideal habitat regions are considered "mesic" (containing moderate amounts of rain and moisture) to extremely wet. 
• Although considered strong fliers, they tend to remain in areas of consistent and reliable food source, and therefore do not migrate away to other regions. 
• DIET: The diet of the Puaiohi consists mainly of fruits and is supplemented by small invertebrates such as snails, insects, etc.
• SOCIAL LIFE: Puaiohi are part of a socially monogamous mating system, and live in relatively close proximity with one another. 

PRIMARY THREATS and REASONS FOR LISTING

1. DISEASE

• Puaiohi are susceptible to various avian diseases, including pox and malaria. There is some research to indicate that this prevents them from inhabiting the lower reaches of ravines and some suitable nesting cliffs. 
• Some Puaiohi have been found to have malarial antibodies, suggesting that there is genetic diversity in favor of disease resistance.

2. PREDATION

• Non-native species, especially rats pose an enormous threat to Puaiohi. Almost half of all failed nests (nests where the offspring did not survive or hatch) are attributed to rats. 
• Feral cats are also a threat. Since fledged Puaiohi remain close to the ground for a period after fledging, they are vulnerable to ground predation. 

3. COMPETITION FROM NON-NATIVE BIRDS

• Non-native birds often carry diseases that native birds are not immune to. 
• Competition for resources and prime nesting ground can cause decline in native populations. 
• Some non-native competitors include: the Japanese white-eye, the melodious laughing thrush, and the white-rumped shama (seriously, who names these?)

4. HABITAT DEGRADATION

• Perhaps one of the most prevalent threats, habitat degradation comes from multiple sources:
  Other animal species: Introduced species such as feral pigs and goats cause damage to the forests of Hawaii, causing a decline in habitat quality and increased edge condition.
  Humans:  development of urbanized areas leads to the degradation of habitat quality. The remaining Puaiohi habitat is fortunately protected as a wildlife preserve, but additional possible habitat is still under threat to human development. 

Juvenile Puaiohi

photo: Kyle Pias

DELISTING EFFORTS

EFFORTS TOWARDS CONSERVATION

Current conservation efforts include the following:

• LEGAL PROTECTION: creating laws that protect the Puaiohi, other Hawaiian native birds, and their habitat. 
• ECOLOGICAL STUDIES: efforts to understand the ecology of the Puaiohi, and the underlying reasons for its endangered status in order to better recover the species. 
• CAPTIVE PROPAGATION + REINTRODUCTION: Breeding in captivity allows for both lifecycle observation as well as increased chance of growing the population through controlled and protected nesting. 
• PERIODIC SURVEYS AND INVENTORIES: Keeping tabs on the wild population as well as the state of the habitat helps to determine what efforts are working, what stochastic events are impactful, and how the population is doing as a whole. 
• CONTROL OF FERAL SPECIES: Since feral species, such as the cat and the pig, pose such a threat, eradication and control of such species can cause a negative feedback loop (which means restoring the population to equilibrium, or healthy population size) for the Puaiohi. In other words: "negative feedback loop" is a good thing in conservation biology. 
• SMALL MAMMAL CONTROL: similarly to the control of feral species is the control of small mammals to which the Puaiohi are prey, such as rats.
• INFORM AND EDUCATE THE PUBLIC: As equally important in the effort of conservation biologists to delist the Puaiohi is to inform the public on the need and status of the Puaiohi. Without public and local support and awareness, it can be difficult to make a positive change for the endemic species. 

STRATEGIES FOR RECOVERY:

Considering the efforts listed above, the recovery strategy is very similar: 

• Protect the habitat of the Puaiohi 
• Control the overgrowth of predatory species
• Aid in the population increase through captive breeding and reintroduction
• Survey and monitor the wild population in order to keep tabs on the success of efforts as well as naturally occurring responses. 
• Research and identify limiting factors, or events and conditions that prevent the recovery of the Puaiohi. 

photo: Lucas Behnke

ULTIMATE GOAL: RECOVERY

In order to DOWNLIST the Puaiohi from "Endangered" to "Threatened" on the Endangered Species List, three goals must be achieved:

1. The total population of Puaiohi must exceed 1,000 mature individuals in at least 5 separate subpopulations (that make up one metapopulation). 
2. The viability - or stability - of these populations must be proven through surveys (quantitative) that show an consistent 15 year increase in the population or through demographic monitoring that indicates a growth rate of no less than 1.0 during 15 consecutive years and no expectation for population decline of more than 1/5 in the proceeding 15 years. 
3. There must be enough "sufficient habitat in recovery areas" (Revised Recovery Plan). 

In order to reach the final goal of DELISTING, the above three goals must be achieved with the addendum of

1. The total population of Puaiohi must exceed 2,000 mature individuals in at least 5 separate subpopulations (that make up one metapopulation). 
2. The viability - or stability - of these populations must be proven through surveys (quantitative) that show an consistent 30 year increase in the population or through demographic monitoring that indicates a growth rate of no less than 1.0 during 30 consecutive years and no expectation for population decline of more than 1/5 in the proceeding 15 years. 
3. There must be enough "sufficient habitat in recovery areas" (Revised Recovery Plan). 

Information drawn from the following sources:

• Behnke, Lucas. "Puaiohi." Kauai Forest Birds Recovery Project. Kauai Forest Birds Recovery Project, n.d. Web. 08 June 2015.
• BirdLife International 2013. Myadestes palmeri. The IUCN Red List of Threatened Species. Version 2015.1. <www.iucnredlist.org>. Downloaded on 06 June 2015.
• "Puaiohi - Myadestes Palmeri." Wildscreen Arkive. Wildscreen Archive, n.d. Web. 08 June 2015.
• United States. U.S. Fish and Wildlife Service. Endangered Species. Revised Recovery Plan for Hawaiian Forest Birds. By Ren Lohoefener. Portland, OR: n.p., 2006. Web.