How to Identified Greater Sand Plover Tibetan Sand Plover and Siberian Sand Plover

Identification Differences within the Sand Plover Complex:

The sand plover complex, traditionally divided into Greater Sand Plover (Charadrius leschenaultii) and Lesser Sand Plover (Charadrius mongolus), reveals important distinctions through recent phylogenetic and genomic studies. While previously grouped based on morphology and some overlapping traits, the complexity of their identification, particularly between the now-recognized species of Siberian Sand Plover (Anarhynchus mongolus) and Tibetan Sand Plover (Anarhynchus atrifrons), showcases how similar-looking species are often not closely related. Below are the key identification features that distinguish these species:

1. Siberian Sand Plover (A. mongolus) vs. Tibetan Sand Plover (A. atrifrons):

Size and Structure:

• Siberian Sand Plover:
  • Averages slightly larger with a deeper chest and bulkier appearance.
  • Shorter bill with a more pronounced culmenary bulge near the tip, giving it a blunter appearance.
  • Shorter tarsus and wings, which makes the toes barely project beyond the tail when in flight.
• Tibetan Sand Plover:
  • Often looks slimmer and more proportionate.
  • Longer bill, especially in the eastern subspecies (A. a. schaeferi) and (A. a. atrifrons), with a more pointed tip.
  • Longer tarsus, longer wings, and a more obvious toe projection beyond the tail in flight, particularly in the western subspecies (A. a. pamirensis).

Plumage (Winter and Summer Differences):

• Siberian Sand Plover (Winter):
  • Slightly darker ear-coverts than the crown and nape.
  • A well-defined triangular white forehead patch bordered by darker feathers.
  • Breast-band is usually complete or almost so, with some birds showing diagnostic dusky feathers along the flank.
• Tibetan Sand Plover (Winter):
  • Ear-coverts concolorous with the crown and nape.
  • The white on the forehead blends gradually into the brown forecrown without a clear border.
  • Breast-band usually incomplete with white, unmarked flanks.
• Siberian Sand Plover (Summer):
  • Generally darker brown upperparts.
  • The brown on the central rump is broad with minimal white on the sides of the rump.
  • Dusky underwing coverts and axillaries, often showing dusky markings.
• Tibetan Sand Plover (Summer):
  • Paler and warmer brown upperparts.
  • Narrower brown central rump with more white on the rump sides.
  • White underwing coverts and axillaries.

In-flight Distinctions:

• Siberian Sand Plover:
  • Longer-winged appearance, particularly noticeable during flight.
  • Only four inner primaries show the white base of the wings, and the wing-bar is generally thinner.
• Tibetan Sand Plover:
  • Wing-bar tends to be broader and the white on the primaries is more extensive than in Siberian Sand Plover.
  • Toe projection beyond the tail in flight is more obvious, especially in the western subspecies.

2. Vocalization and Behavioral Differences:

• Siberian Sand Plover has distinct calls compared to both Tibetan Sand Plover and Greater Sand Plover, whose vocalizations are more similar. This highlights a key behavioral and ecological distinction between the species.

3. Phylogenetic Background and Genetic Distinction:

Recent genomic analysis (Wei et al. 2022) confirms that the traditional Lesser Sand Plover group is not monophyletic. Tibetan Sand Plover is more closely related to Greater Sand Plover, while Siberian Sand Plover forms a separate lineage. These findings challenge the previous assumptions based on morphological similarities and propose that Tibetan and Siberian Sand Plovers are not each other’s closest relatives.

Conclusion:

The sand plover complex exemplifies how morphological similarities can be deceptive, and phylogenetic evidence must be considered to correctly identify species. Siberian Sand Plover (A. mongolus) and Tibetan Sand Plover (A. atrifrons) exhibit subtle but significant differences in structure, plumage, and behavior, underscoring the need for careful observation in the field to distinguish between these two species.