Distribution and status of the Pallas’s Fish Eagle Haliaeetus leucoryphus in Mongolia: a cause for conservation concern?

Thirty-four traceable locations were identified in the historical literature.

“Thirty-four traceable locations were identified in the historical literature, of which breeding activity had been recorded in seven.”

• Also stated in: § Field surveys · plain

  “A total of 77 sites were visited including 21 of the 34 traceable, historical PFE sites (Table S2 and Figure 2 )”

Breeding activity had been recorded in seven historical locations.

“of which breeding activity had been recorded in seven.”

• Also stated in: § Historical literature review · plain

  “only five referred to breeding PFEs at seven sites (Table S1 in the online supplementary materials).”

All sites where Pallas's Fish Eagles were observed were historical PFE locations.

“all of which were historical PFEs locations”

• Also stated in: § Field surveys · plain

  “all of which were known historical sites”

Pallas's Fish Eagles were observed at eight sites during field surveys.

“PFE were observed at eight sites, all of which were historical PFEs locations, and no evidence of breeding activity was recorded.”

• Also stated in: § Field surveys · plain

  “PFEs were observed at eight sites ( Table 1 ), all of which were known historical sites.”

Pallas's Fish Eagles were not detected at 13 of 21 historical sites surveyed.

“The lack of eagles at 13 of 21 historical sites surveyed, coupled with a lack of sightings of birds at alternative locations is suggestive of a decline in site occupancy.”

• Also stated in: § Discussion · hedged

  “Our failure to detect PFEs at 13 of 21 historical sites may be indicative of a decline in site occupancy of PFEs in our study area.”

No evidence of breeding activity was recorded during field surveys.

“no evidence of breeding activity was recorded.”

• Also stated in: § Discussion · plain

  “our own contemporary surveys at 15 of these locations made during the same months did not produce any evidence of PFE breeding.”

All observations of Pallas's Fish Eagles were made on lakes except a single individual recorded along Chono Kharaikh Gol, at elevations between 1,030 m and 1,988 m.

“All observations of PFEs were made on lakes with the exception of a single individual recorded along Chono Kharaikh Gol [river], at elevations between 1,030 m and 1,988 m.”

There was a significant association between sites where Pallas's Fish Eagles were observed and where Great Cormorants were present (chi-value = 7.586, df = 1, P = 0.006).

“There was a significant association between sites where PFEs were observed and where Great Cormorants were present (chi-value = 7.586, df = 1, P = 0.006).”

Of 40 observations where the number of eagles was specified, only three reported more than two birds present.

“Of the 40 observations where the number of eagles was specified, only three reported more than two birds present: five birds of S1.”

Recent construction of hydroelectric dams on the Chono Kharaikh Gol and Zavkhan Gol has disrupted water flow at several historical and contemporary Pallas's Fish Eagle sites.

“The recent construction of hydroelectric dams on the Chono Kharaikh Gol and Zavkhan Gol has disrupted water flow at several historical and contemporary PFE sites (including sites 9, 11 and 30 along the watershed of the dam at Chono Kharaikh Gol, and sites 3, 76, and 90, downstream from the Zavkhan Gol dam, Figures 1 and 2 ).”

Within 29 published historical accounts referring to April-October, only five specifically mentioned Pallas's Fish Eagle breeding activity.

“Within 29 published historical accounts referring to these months, only five specifically mentioned PFE breeding activity (presence of nests or an egg).”

Juvenile Pallas's Fish Eagles were observed in fresh plumage as early as June.

“On several occasions juvenile eagles were observed in fresh plumage (with little or no evidence of wear) as early as June (pers.obs.and M. Valkenburg and W. Faveyts in litt .2010).”

Only one reference quantified breeding attempts at a specific location with a single nest containing a single egg on 24 June 1999 at Tsagaan Gol, Khar-Us Nuur.

“Only one reference (Sh.Boldbaatar in Stubbe et al. 2010 ) quantified breeding attempts at a specific location with a single nest containing a single egg on 24 June 1999 (at Tsagaan Gol, Khar-Us Nuur).”

• cites Sh.Boldbaatar in Stubbe et al. 2010Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Contemporary surveys at 15 historical locations where no evidence of breeding was recorded did not produce any evidence of Pallas's Fish Eagle breeding.

“our own contemporary surveys at 15 of these locations made during the same months did not produce any evidence of PFE breeding.”

Within 30 references where Pallas's Fish Eagles were mentioned, only five referred to breeding PFEs at seven sites.

“Within the 30 references where PFEs were mentioned, only five referred to breeding PFEs at seven sites (Table S1 in the online supplementary materials).”

Pallas's Fish Eagles were only observed on relatively large water bodies ranging from 25 to 1,077 km2.

“with PFEs only observed on relatively large water bodies ranging from 25 to 1,077 km 2 (Table S2).”

No evidence of breeding was found at 55 widely dispersed wetlands not documented in the historical literature, representing potential alternative breeding sites.

“we failed to find any evidence of breeding at 55 widely dispersed wetlands that were not documented within the historical literature review, and represented potential alternative breeding sites.”

With the exception of a museum specimen collected at Khuvsgul Nuur on 24 December 1912, all historical observations of Pallas's Fish Eagles in Mongolia were made between April and September.

“With the exception of a museum specimen collected at Khuvsgul Nuur on 24 December 1912 (by F. Schillinger, in Piechocki 1983 ), all historical observations of PFEs in Mongolia were made between April and September.”

Pallas's Fish Eagle is classified as Vulnerable on the IUCN Red List.

“classified as 'Vulnerable' by IUCN on the basis of population size and reports of declines in many areas.”

• Also stated in: § Introduction · plain

  “Classified as 'Vulnerable' on the IUCN Red List (BirdLife International 2012b )”

• cites BirdLife International 2012bNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

The lack of eagles at 13 of 21 historical sites, coupled with lack of sightings at alternative locations, is suggestive of a decline in site occupancy of Pallas's Fish Eagle in Mongolia.

“The lack of eagles at 13 of 21 historical sites surveyed, coupled with a lack of sightings of birds at alternative locations is suggestive of a decline in site occupancy.”

• Also stated in: § Discussion · hedged

  “Our failure to detect PFEs at 13 of 21 historical sites may be indicative of a decline in site occupancy of PFEs in our study area.”

• Also stated in: § Conclusions · plain

  “The population that is there is small and there is evidence of a decline in site occupancy.”

Pallas's Fish Eagle populations are thought to be declining across substantial parts of their range.

“populations are thought to be declining across substantial parts of its range (BirdLife International 2001, 2012a, Sourav et al. 2011, Gombobaatar et al. 2011 ).”

• cites BirdLife International 2001Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites 2012aNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Sourav et al. 2011Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

At least a proportion of Mongolian Pallas's Fish Eagles are breeding at southern latitudes.

“Observations of juvenile eagles within one month of the spring thaw suggests that at least a proportion of Mongolian PFEs are breeding at southern latitudes, and future studies to establish these migratory linkages are warranted.”

• Also stated in: § Conclusions · hedged

  “it is likely that these birds hatched in locations south of Mongolia, and may be individuals from the breeding population in the Indian subcontinent.”

The surveys were not comprehensive because 18 historical locations were not visited.

“our surveys were not comprehensive, as we were unable to visit a further 18 historical locations.”

There is likely a continuing decline in the number of mature Pallas's Fish Eagle individuals.

“We also agree with part (2), that there is likely a continuing decline, observed, projected or inferred, in the number of mature individuals.”

The population of Pallas's Fish Eagle in Mongolia is small.

“The population that is there is small and there is evidence of a decline in site occupancy.”

The Pallas's Fish Eagle current population size is probably fewer than 2,500 mature individuals.

“The next numerical threshold used by IUCN to trigger a status of 'Endangered' is a population size estimated to number fewer than 2,500 mature individuals; we suggest this figure is probably a more realistic estimate of the PFE's current population size.”

With the possible exception of a relict population in Kazakhstan, all remaining northern Pallas's Fish Eagle populations migrate to southern latitudes during the northern winter.

“With the possible exception of a relict population in Kazakhstan, it appears that all remaining northern populations migrate to southern latitudes during the northern winter.”

It seems likely that the Mongolian Pallas's Fish Eagle population winters in latitudes south of the Himalayas.

“it seems likely that the Mongolian population winters in latitudes south of the Himalayas, but further work is required to establish the nature of this connectivity.”

Even if the 18 unvisited historical sites are currently occupied by breeding Pallas's Fish Eagles, this would still not amount to a breeding stronghold.

“Although we may have missed evidence of breeding at the historical sites that we were unable to visit, even if those 18 sites are currently occupied by breeding PFEs this would still not amount to a breeding stronghold.”

The Pallas's Fish Eagle population size is unlikely to exceed 10,000 mature individuals.

“We agree that the population size is unlikely to exceed 10,000 mature individuals, but importantly we would suggest that this threshold (which triggers the status of 'Vulnerable') is probably a considerable overestimate and should now be reviewed, especially given the lack of both historical and contemporary evidence of a large breeding population in Mongolia.”

The current IUCN classification of Pallas's Fish Eagle as Vulnerable may no longer be an accurate reflection of the species' conservation status.

“These declines, coupled with the results of our study, suggest that this classification may no longer be an accurate reflection of the species' conservation status.”