{{Blwch tacson
| enw = Tylluan Wen
| delwedd = Barn_owls_revivim.jpg
| maint_delwedd = 225px
| neges_delwedd = 
| regnum = Animalia
| phylum = Chordata
| classis = Aves
| ordo = Anseriformes
| familia = Anatidae
| genus = '''''Anas'''''
| species = '''''A. strepera'''''
| enw_deuenwol = ''Anas strepera''
| awdurdod_deuenwol = (Linnaeus, 1758)
}}
Mae'r '''Hwyaden Lwyd''' (''Anas strepera'') yn un o'r hwyaid mwyaf cyffredin trwy rannau helaeth o'r byd, yn Ewrop, Asia a Gogledd America. Yn y rhannau lle mae'r gaeafau yn oer, mae'n aderyn mudol, yn symud tua'r de i aeafu. 

Hwyaden ganolig o ran maint ydyw, rhwng 46 a 56 cm o led ac 78-90 cm ar draws yr adenydd. Gellir adnabod y ceiliog yn hawdd, gyda'i gorff lwyd a thu ôl du amlwg, gyda gwyn ar yr adenydd. Mae'r iâr yn anoddach ei hadnabod, gan ei bod yn edrych yn debyg iawn i iâr Hwyaden Wyllt, er ei bod ychydig yn llai. 

Adeiledir y nyth mewn corsydd neu ar lannau llynnoedd. Plangigion yw'r prif fwyd, ond mae'r cywion yn cael eu bwydo ar bryfed, ac mae'r oedolion yn bwyta rhywfaint o ymlusiaid yn y tymor nythu. Yn y gaeaf gallant gasglu at ei gilydd yn heidiau bychain ond anaml y'i gwelir mewn heidiau mawr fel rhai o'r hwyaid eraill.

Mae'r Gymru. Credir fod ei niferoedd yn cynyddu'n raddol.

{{Taxobox
| name = Gadwall
| status = LC
| status_ref =<ref name= IUCN> Database entry includes justification for why this species is of least concern</ref>
| image = Anas strepera pair.jpg
| image_width = 200px
| image_caption = male with female behind
| regnum = Animalia
| phylum = Chordata
| classis = Aves
| ordo = Anseriformes
| familia = Anatidae
| genus = ''Anas''
| species = '''''A. strepera'''''
| binomial = ''Anas strepera''
| binomial_authority = Linnaeus, 1758
| subdivision_ranks = Subspecies
| subdivision = 
* ''A. s. strepera''<br><small>(Common Gadwall)</small>
* ''A. s. couesi''<br><small>(Coues' Gadwall - '''extinct''')</small>
}}

The '''Gadwall''', ''Anas strepera'' is a common and widespread Linnaeus in his ''Systema naturae'' in 1758 under its current scientific name.<ref> </ref>

==Description==
thumb|left| Male & Female in   [[Kolkata. ]]
thumb|left| In  kolkata
thumb|left| Male & Female Up-ending in  Kolkata 
The Gadwall is 46-56 cm long with a 78-90 cm wingspan. The breeding male is a beautifully patterned grey, with a black rear end and a brilliant white speculum, obvious in flight or at rest. In non-breeding (eclipse) plumage, the drake looks more like the female.

The females are light brown, with plumage much like a female speculum.

==Distribution==
The Gadwall breeds in the northern areas of migratory and winters further south than its breeding range.

In Great Britain the Gadwall is a scarce breeding bird and winter visitor, though it has increased in recent years. It is likely that its expansion was partly through introduction, mainly to England, and partly colonisation Great Britain, with continental birds staying to breed in Scotland.

==Behaviour and habitat==

The Gadwall is a bird of open wetlands, such as prairie or steppe lakes, wet grassland or marshes with dense fringing vegetation, and usually feeds by dabbling for plant food with head submerged. It nests on the ground, often some distance from water. It is not as gregarious as some dabbling ducks outside  the breeding season and tends to form only small flocks. This is a fairly quiet species; the male has a hoarse whistling call, and the female has a Mallard-like quack. The young birds are fed insects at first; adults also eat some mollusks and insects during the nesting season. The Gadwall is one of the species to which the ''Agreement on the Conservation of African-Eurasian Migratory Waterbirds'' (AEWA) applies.

==References==