Green Sandpiper

With some departing their breeding grounds even while the last spring migrants are still arriving, Green Sandpiper is very much the advance guard of autumn migration. This species is likely to be our first reward if we are restarting nocmig sessions after an early summer break.

Flushing a Green Sandpiper by day, you may hear alarm calls as it takes off, soon followed by kluuit-klit-klit calls as it flies further away. This is the same call that we hear from migrating individuals at night.

Green Sandpipers rarely congregate in large groups; most nocturnal migrants fly alone or with a handful of companions. Single birds and flocks use very similar calls, and rarely add any other call-type while migrating. For the sake of completion, we include two others below, which we have heard only in the context of flocks.

kluuit-klit-klit call

• level series of medium-pitched whistles, each rising sharply rising at the end
• first whistle is twice as long as any that follow
• 3 or 2 whistles per series typical; anything from 1 to 6 per series not unusual
• wide frequency range, with each call consisting of 3 parts
  • the k– part, a brief ‘foot’ around 2.1 kHz with a strong harmonic around 4.2 kHz, at the end of a delicate, straight ‘foreleg’
  • the –luui- or –li– part, a shallow V-shape in the first whistle or a rapid dip in subsequent whistles; often appears broken up, sounding like lu-ui (b, d, f  & h) or lu-u-i (a); in fact, there are spindly U-shaped connecting links (eg, f); mean lowest point of V is 3.2 kHz (range 1.5 – 3.8 kHz; n = 44), ignoring barely visible links (eg, f)
  • the –it part, which is loudest, a rapidly rising slope ending in a hook; mean max frequency 5 kHz (range 4.0 – 6.4 kHz; n = 45)
• not markedly different in flocks, but see below

flocks

• excited flocks sometimes give ‘endless’ kluuit-klit-klit-klit-klit…. calls (i); we have heard up to 24 klits in a row
• on a couple of occasions, we have come across a quiet series of short arched or peaked pit-pit-pit… notes in among kluuit-klit-klit calls (j); maximum frequency around 4 – 4.5 kHz

Effects of recording quality

• Closer calls show ‘feet’ and ‘forelegs’ at the start of each whistle, and a second harmonic at double the frequency of the entire call (eg, a & h). In the closest calls, if the first whistle is fragmented, it may be possible to discern the spindly U-shaped connecting links between fragments (f & h).
• More distant calls lack ‘feet’ and ‘forelegs’ at the start of each whistle, and with very distant calls it may only be possible to discern the highest -it part of each whistle (d).

• Common Sandpiper Actitis hypoleucos also has NFCs consisting of a series of rising whistles, but they are much higher-pitched, occupy a narrower frequency range, and the first whistle is shorter, not longer than the ones that follow. ‘Endless’ variants of kluuit-klit-klit-klit-klit… may invite confusion with Common when the longer first whistle is obscured among calls of many individuals. In this case the lower pitch is the most important clue.

• anywhere: over towns, forests, mountains and offshore
• any time: both diurnal and nocturnal
• can be heard all night: peak activity towards the end of the night