v1.0
Published 01/10/24
ròcas m. [ˈɍɔːʰkəs̪], gen. ròcais -[iʃ], along with variants, ‘a member of the Corvidae family of birds, usually rook, Corvus frugilegus, 
MacDomhnuill 1741, 74; Shaw 1780; Mac Farlan 1795; McAlpine 1832: Islay; Fergusson 1886, 46; Dieckhoff 1932: Glengarry; Holmer 1938, 204: Islay; Cunningham 1990, 178; Garvie 1999, 65; Wentworth 2003, s.v. rook: Gairloch; Grannd 2013, s.v. rook: North Sutherland; Ó Murchú 2021, 306: West Perthshire; Faclan bhon t-Sluagh˄: Harris (Scalpay), North and South Uist, Tiree, Islay, East Sutherland, Killin; AFB˄.
less commonly crow, Corvus corone, 
Henderson 1910, 122; MacBain 1911; Watson 2022, 273: Easter Ross; Faclan bhon t-Sluagh˄: Mull, Arisaig. The following cite ‘rook or crow’: Armstrong 1825; HSS 1828; CG VI, 119; Forbes 1905, 35; Dwelly 1911.
occasionally raven, Corvus corax 
Faclan bhon t-Sluagh˄: Glen Urquhart.
or jackdaw, Coruvs monedula. 
Faclan bhon t-Sluagh˄: North Argyll.
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Oftedal’s (1956, 72) ‘starling, Sturnus vulgaris’ is probably in error.
Several forms are found:
A.
A 1. SG ròcas [ˈɍɔːʰkəs̪]
(i) ròcas
(Armstrong 1825; HSS 1828; MacBain 1896; CG VI, 119; Henderson 1910, 122; Dwelly 1911; Cunningham 1990, 178; Garvie 1999, 65; Wentworth 2002, s.v. rook: [Rɔːʰkəs], Gairloch; Faclan bhon t-Sluagh˄: [rɔʰkəs], Killin; AFB˄: /Rɔːxgəs/) and ròcus (Armstrong 1825); (pl.) ròcais (Holmer 1938, 204: [rɔːhkiʃ]; Ó Murchú 2021, 306: /rɔːxgɩš/);
(ii) rocas (Forbes 1905, 35; Dieckhoff 1932: [RòːKgəs]) and rocus (Shaw 1780; Mac Farlan 1795; Fergusson 1886, 46; Forbes ibid.), omitting the lengthmark;
(iii) ròc is given by Dwelly (1911), quoting a ‘new edition’ of MacEachen’s Gaelic-English dictionary, but apparently in error: MacEachen’s 1st edition (1842) gives rocuis (sic), while his 3rd edition (1906) gives ròcas and ròcais.
A 2. SG ròcais [ˈɍɔːʰkiʃ]
With a palatalised sibilant:
(i) ròcais (Faclan bhon t-Sluagh˄: North and South Uist, Mull, Arisaig, [rɔ:kiʃ] Glen Urquhart, [rɔ:kiʃ] East Sutherland; Grannd 2013: North Sutherland) and rócis (sic) (MacDomhnuill 1741, 74);
(ii) rocuis and rocis (Forbes 1905, 25), omitting the lengthmark;
(iii) ròchdais (Faclan bhon t-Sluagh˄: [rɔ:ʰkiʃ], North Argyll), cf. SG sloc (< ON *slǫkk nt. ‘hollow’) > slochd (s.v. sloc).
A 3. SG rògais [ˈɍɔːɡ̊iʃ]
With voiceless /ɡ/ (Oftedal 1956, 72: /ʀɔːɡiʃ/, Lewis; Watson 2022, 273: /roːɡiʃ/, Easter Ross).
B. SG ròcaideach [ˈɍɔːʰkad̥ʲəx], ax]
(i) ròcaideach (Faclan bhon t-Sluagh˄: Islay; AFB˄: Tiree, Islay);
(ii) rocaideach (McAlpine 1832: [rôchg´- ăj-ach], Islay; Faclan bhon t-Sluagh˄: Tiree), omitting the lengthmark.
C. rochaich
This form occurs in a short list of bird names drawn up by a nine-year-old informant from Scalpay (Faclan bhon t-Sluagh˄, q.v.), but this is probably for ròcais – the list contains several spelling errors.
SG ròcas is thought to derive from SG ròc ‘hoarse sound or voice’ + the Gaelic suffix -as, which in turn is said to derive from ON hrókr m. ‘rook’ (cf. HSS 1828; MacBain 1896; 1911; Forbes 1905, 257, 330; Henderson 1910, 122, so also Lockwood 1961, 21, and de Vries 1962; Stewart 2004, 412; McDonald 2009, 365; 2015, 125–26). While Cleasby (1874) and Zoëga (1910) translate OIce. hrókr as ‘rook’, 
The sense of Mod. Ice. hrókur is ‘(in chess) rook, castle’.
ON hrókr means ‘shag, Phalacrocorax aristotelis; also lanky clumsy fellow’. ON hrók acc. would formally yield SG *[ˈɍɔːɡ̊], s.v. ròg.
SG ròcas, ròcais and ròcaideach appear to be based on SG ròc (also found spelt ròchd) ‘a hoarse sound (e.g. harsh voice, cough, croak, caw)’, 
Cf. SG ròc vb. ‘to make a hoarse sound’, ròcach adj. ‘hoarse’, ròcail f. ‘croaking, cawing’, ròcan m. ‘hoarseness’.
possibly from Scots rauk [rɑːk], [rɔːk] adj. ‘hoarse, raucous’ and/or rauk vb ‘to clear the throat’ (cf. SND˄, s.v. 1rauk, < EScots rauk ‘hoarse, raucous’, OFr rauque, Lat. raucus ‘harsh, raucous’), although it might be onomatopoeic. The ending -as seems to be otherwise unknown in bird names.
Dwelly (1911) lists piocas ‘magpie’, probably from Armstrong (1825), who claims to quote Shaw (1780); however, the latter gives only pighaid (sic), and Armstrong’s picas appears to be in error, perhaps from confusion with the bird’s ornothological name Pica pica.
While it echoes the ending of Eng. raucous (< Lat. raucus, with substitution of the English adjectival ending -ous (OED˄)), it may simply derive from the Scots/Eng. plural morpheme -s (cf. SG briogais, s.v., < Scots breeks), ròcas and the by-form ròcais as a singulative perhaps arising out of an initial collective use; 
MacLennan (1925) cites Ir. rócas ‘rook, crow’, perhaps from O’Reilly’s Irish dictionary (1817; 1864), which gives rocas (sic) ‘rook, crow’ and rócus ‘rook’; contrast Ir. rúcach ‘rook’ (Dinneen 1947: ‘rook, crow’; Ó Dónaill 1977).
for ròcaideach, cf. faghaideach ‘carnivorous bird’ (< faghaid ‘hunt, chase’ + the suffix -ach).