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Federal Register / Vol. 86, No. 150 / Monday, August 9, 2021 / Proposed Rules
In the October 10, 2019, CNOR, the Okinawa woodpecker was assigned an LPN of 2. After reevaluating the available information, we find that no change in the LPN is warranted. The Okinawa woodpecker does not represent a monotypic genus. Threats to the species are high in magnitude due to the scarcity of its old-growth habitat.
The population is very small and is likely declining. Although new protected areas have been established that will likely benefit the Okinawa woodpecker, it is not yet clear that these areas will be fully protected from logging and other anthropogenic development and nonnative predators.
Even though threats from logging have been reduced, it will take many years for secondary and clear-cut forest habitat to mature such that it is suitable for the woodpecker. The threats to the species are ongoing, imminent, and high in magnitude due to its restricted range, small population size, past habitat loss, and endemism. Therefore, an LPN of 2
remains valid for this species to reflect imminent threats of high magnitude.

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Invertebrates Colorado Delta Clam Colorado delta clam Mulinia modesta is a relatively large, estuarine bivalve that was once very abundant at the head of the Gulf of California in the Colorado River estuary in Mexico prior to the construction of dams on the Colorado River. Recognizing that the clam is M. modesta, we now also recognize that the clam has a broader distribution into the northern and central portions of the Gulf of California. Therefore, the species is more widespread and found in the upper, northern, and central portions of the Gulf of California, and is capable of living in salinities ranging from brackish mixture of salt and fresh water to full seawater.
Information regarding abundance of the Colorado delta clam in the Gulf of California is limited. The minimum average standing population of the Colorado delta clam in the upper Gulf was estimated to be at least 5 billion individuals over the past 1,000 years to account for the shells accumulated in ridges, with the delta clam accounting for 8495 percent of all bivalve mollusks in the upper Gulf. However, after decades of dam building on the Colorado River and its tributaries, the Colorado delta clam is estimated to be 6 percent as abundant in the upper Gulf as it was before dam construction began.
While it is clear the clam has declined dramatically in the upper Gulf where it was most abundant before Colorado
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River dams were built, we are not aware of total population estimates covering its full range because benthic surveys of the near-coastal invertebrate macrofauna in central and southern Gulf are lacking.
The species has not been assessed for the IUCN Red List. It is not commercially harvested or known to be in international trade, and is not included in the Appendices to CITES.
Although the specific causes for the dramatic decline of the clam in the Colorado delta and upper Gulf of California region have not definitively been identified, several researchers have indicated that it was a consequence of decrease in the Colorado Rivers inflow to the estuary since completion of the dams. Environmental changes to the estuary associated with the decrease in river inflow include increased salinity, decreased sediment load, decreased input of naturally derived nutrients, and elimination of the spring/summer flood.
Dams and diversions along the Colorado River have greatly affected the estuarine environment of the Colorado delta and have likely caused the localized decline in abundance of the clam in this region.
However, the best available information does not indicate that dams and diversions are a stressor for the Colorado delta clam elsewhere within its range in the northern and central portions of the Gulf of California.
Additionally, stressors for the clam throughout its range may arise from other natural or manmade factors affecting the clams continued existence, such as pollution-related problems and effects from climate change, which are likely to increase in the future.
In the October 10, 2019, CNOR, the Colorado delta clam was assigned an LPN of 8. With the confirmation that the clam is Mulinia modesta, we recognize that it has a broader distribution into the northern and central portions of the Gulf of California and is capable of living in full seawater. However, we lack information about the distribution and viability of populations of the clam outside of the Colorado delta region.
Despite the conservation measures in place primarily portions of the species range occurring within two large protected areas, the species continues to face habitat loss and degradation in the Colorado delta region due to dams and diversions on the Colorado River, along with other changes associated with decrease in river inflow and pollution. Because this threat appears to be affecting the clam in upper Gulf of California, and not in the remainder of its range, it is moderate in magnitude.
The threat of habitat loss and degradation in the Colorado delta region is ongoing and imminent. Therefore, an
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LPN of 8 remains valid for this species to reflect imminent threats of moderate magnitude.
Fluminense Swallowtail Fluminense swallowtail Parides ascanius is a black, white, and red swallowtail butterfly. The species may be confused with the Harris mimic swallowtail, but the Harris mimic has a red streak on the underside of its wing.
The fluminense swallowtail also inhabits the restinga sand forest habitats of the coastal Atlantic Forest of Brazil within the State of Rio de Janeiro.
There are at least eight confirmed subpopulations of fluminense swallowtail, and several other small, likely ephemeral, subpopulations are currently being studied i.e., 812
estimated subpopulations. The overall number of subpopulations reported for the species has declined from fewer than 20 colonies in 1994, to 8 to 12 in 2017. The butterfly is described as seasonally common, with sightings of up to 50 individuals at one colony in a single morning. A study at Biological Reserve of Poc o das Antas estimated that the subpopulation ranged from 10
to 50 individuals. The best available information does not provide estimates for butterfly numbers in the remaining subpopulations. The best available information indicates that there is a decline of subpopulations as well as a decrease in the numbers of individuals within each subpopulation. An estimate of the total area occupied by this species is less than 500 square kilometers 193
square miles.
Habitat loss, degradation, and fragmentation are the primary threats to this species. The species occupies highly specialized habitat and requires large areas to maintain a viable colony.
Based on a number of estimates, 88 to 95 percent of the area historically covered by tropical forests within the Atlantic Forest biome has been converted or severely degraded as a result of human activities. Habitat loss and destruction is caused primarily by road and building construction, drainage of swamps, and vegetation suppression, and the remaining tracts are severely fragmented. Fire, either wildfire or human-caused, has the potential to destroy the few remaining occupied habitats. This coastal butterfly may also be affected by habitat loss from sea-level rise, which may be compounded by human use of the remaining land for infrastructure and housing. The species life history also contributes to its scarcity. Fluminense swallowtails, whose larvae feed only on a single plant species, tend to be more affected by habitat degradation than
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