Geology topics

Lindsey Nietmann

Publications and source records attributed to Lindsey Nietmann.

3 recordsLinked to original sources

USGS2025

The continued decline of the Palila (Loxioides bailleui) on Mauna Kea, Island of Hawaiʻi

Palila ( Loxioides bailleui ) are critically endangered Hawaiian honeycreepers specializing on māmane ( Sophora chrysophylla ) seeds and restricted to Mauna Kea volcano on the Island of Hawaiʻi. Recently, the population was estimated to decline by 89% between 1998 and 2021, despite decades of ungulate removal, fence construction, māmane regeneration, fire suppression, and predator control. To inform managers with the most recent update on the status and trends of the Palila population, we analyzed annual bird survey data collected using point-transect distance sampling since 1998, including new annual survey data from 2022, 2023, and 2024. Prior to analysis, we predicted the population trajectory would change between 2021 and 2024 because of continued management actions promoting habitat recovery. We used distance sampling, log-linear regression, and state-space modeling to produce the new estimates and analyze trends across the time series. The 2022 population estimate was 367 to 742 birds (95% confidence interval; point estimate: 545), the lowest in recorded history. The 2023 and 2024 estimates of 374 to 842 birds (point estimate: 596) and 412 to 970 birds (point estimate: 666) were the second and third lowest in our time series, respectively. Our estimates for years before 2022 show population fluctuations between 4000 to 6800 birds from 1998 to 2005, then a steep decline through 2010. For the next decade, abundance fluctuated around 1000 birds, before declining again in 2021 to less than 700 birds. From 1998 to 2024, the population declined by more than 90%, or 205 birds per year, with 100% statistical support for an overall downward trend, despite significant management efforts and research. The greatest threats facing the Palila, if familiar, are not being eliminated swiftly enough to promote their recovery. The currently small and range-limited population is vulnerable to future climate-related events such as drought and fire. Continued monitoring can help to assess the response of Palila to adaptive management actions and changing environmental conditions.

Hawaii↗

USGS2025

2022–2024 Status and trends of the Palila (Loxioides bailleui)

Palila (Loxioides bailleui) are critically endangered Hawaiian honeycreepers specializing on the seedpods of māmane (Sophora chrysophylla) and restricted to Mauna Kea volcano on the Island of Hawaiʻi. A previous analysis of survey data estimated an 89% population decline between 1998 and 2021. Using the most recent annual survey data from 2022, 2023, and 2024, we report updated annual population estimates and trends since 1998. The 2022 population estimate was 367–742 birds (point estimate: 545); the 2023 population estimate was 374–842 birds (point estimate: 596); and the 2024 population estimate was 412–970 birds (point estimate: 666). Our estimates for survey years prior to 2022 were within the confidence intervals of the estimates from the previous analysis. Our models likewise showed a population fluctuating between 4,000 and 6,800 birds from 1998 to 2005 (except for an unusually low estimate in 2000), and then a steep decline through 2010. For the next decade, palila abundance fluctuated between 776 and 1,346 birds, before declining again in 2021 to 679 birds. From 1998 to 2024, the population declined by >90% or 203 birds/year, with very strong statistical evidence of an overall downward trend.

Hawaii↗

USGS2023

Forest bird populations at the Pu‘u Wa‘a Wa‘a Forest Bird Sanctuary and Pu‘u Wa‘a Wa‘a Forest Reserve, Hawai‘i

Endemic Hawaiian forest birds have exhibited dramatic population declines since human colonization of Hawai‘i. The Pu‘u Wa‘awa‘a Forest Bird Sanctuary and adjacent Pu‘u Wa‘awa‘a Forest Reserve on Hawai‘i Island were established in 2002 to conserve endemic forest birds and their habitats. Surveys have been conducted in this area to monitor forest bird populations and their response to management actions since 1979. We analyzed point-transect distance sampling survey data collected between 1990 and 2022 in the Pu‘u Wa‘awa‘a Forest Bird Sanctuary and forested portions of the adjacent forest reserve. There were 20 passerine or psittacine species detected of which 6 were native species and 14 were non-native species. In all years, Hawai‘i ‘amakihi (Chlorodrepanis virens virens), ‘apapane (Himatione sanguinea), and warbling white-eye (Zosterops japonicus) were the most abundant species, and in most years ‘i‘iwi (Drepanis coccinea) was the fourth most abundant species. ‘I‘iwi and Hawai‘i ‘amakihi had stable long-term (1990–2022) population trends, and trends for ‘apapane were inconclusive, while warbling white-eye had upward trends. In recent years (2016–2022), ‘apapane had downward trends, ‘i‘iwi and warbling white-eye had upward trends, and trends for ‘amakihi were inconclusive. Populations of Hawai‘i ‘elepaio (Chasiempis sandwichensis) and the endangered Hawai‘i ‘ākepa (Loxops coccineus) and ‘alawī (Loxops mana) were either locally extirpated or in numbers too low to reliably estimate population densities and trends. The Pu‘u Wa‘awa‘a Forest Bird Sanctuary and adjacent Pu‘u Wa‘awa‘a Forest Reserve are important for the conservation of forest birds on Hawai‘i Island as one of few areas of mesic to dry forests being specifically managed for forest bird conservation. Conservation efforts at the Pu‘u Wa‘awa‘a Forest Bird Sanctuary and Pu‘u Wa‘awa‘a Forest Reserve would benefit from continued annual surveys and regular monitoring, and timely analysis of survey data to track responses in forest bird populations to evaluate and adapt management actions.

Hawaii↗