Editing Corvidae (section)

====Tool use, memory, and complex rational thought====
{{See also|Tool use by animals#Corvids}}
[[File:Cognitive-Processes-Associated-with-Sequential-Tool-Use-in-New-Caledonian-Crows-pone.0006471.s002.ogv|thumb|350px|A [[New Caledonian crow]] uses a tool to retrieve the correct tool to obtain food.]]
There are also specific examples of corvid cleverness. One [[carrion crow]] was documented cracking nuts by placing them on a crosswalk, letting the passing cars crack the shell, waiting for the light to turn red, and then safely retrieving the contents.<ref>{{cite web|url=https://www.youtube.com/watch?v=BGPGknpq3e0 | archive-url=https://ghostarchive.org/varchive/youtube/20211107/BGPGknpq3e0| archive-date=7 November 2021 | url-status=live|title=Attenborough – Crows in the City |publisher=YouTube.com |date=12 February 2007 |access-date=9 March 2013}}{{cbignore}}</ref> A group of crows in England took turns lifting garbage bin lids while their companions collected food.{{citation needed|date=February 2025}}

Members of the corvid family have been known to watch other birds, remember where they hide their food, then return once the owner leaves.<ref>{{cite journal|author1=Burnell, Kristi L. |author2=Tomback, Diane F. |author2-link=Diana Tomback|year=1985|jstor=4086793 |title=Steller's jays steal Grey Jay caches: field and laboratory observation|journal=Auk|volume= 102|issue=2|pages=417–419|doi=10.2307/4086793|url=http://sora.unm.edu/node/24119}}</ref><ref>{{cite journal|author=Waite, Thomas A. |year=1992|jstor=1369297 |title=Social hoarding and a load size-distance relationship in Gray Jays|journal=The Condor|url=http://sora.unm.edu/node/104654|volume=94|issue=4|pages=995–998|doi=10.2307/1369297|s2cid=86971311 }}</ref> Corvids also move their food around between hiding places to avoid thievery—but only if they have previously been thieves themselves (that is, they remember previous relevant social contexts, use their own experience of having been a thief to predict the behavior of a pilferer, and can determine the safest course to protect their caches from being pilfered). Studies to assess similar cognitive abilities in apes have been inconclusive.<ref>Owen, James (9 December 2004) [https://web.archive.org/web/20041212040209/http://news.nationalgeographic.com/news/2004/12/1209_041209_crows_apes.html Crows as Clever as Great Apes, Study Says]. ''[[National Geographic News]]'', Retrieved 2007-NOV-10.</ref>

The ability to hide food requires highly accurate [[spatial memories]]. Corvids have been recorded to recall their food's hiding places up to nine months later. It is suggested that vertical landmarks (like trees) are used to remember locations. There has also been evidence that [[California scrub jay]]s, which store perishable foods, not only remember where they stored their food, but for how long. This has been compared to [[episodic memory]], previously thought unique to humans.<ref name = claytonemery2005 />

[[New Caledonian crow]]s (''Corvus moneduloides'') are notable for their highly developed tool fabrication. They make angling tools of twigs and leaves trimmed into hooks, and then subsequently use the hooks to pull insect larvae from tree holes. Tools are engineered according to task, and apparently, also to learned preferences. Recent studies revealed abilities to solve complicated problems, which suggested high levels of innovation of a complex nature.<ref>{{cite news|last=Morelle |first=Rebecca |author-link=Rebecca Morelle |url=http://news.bbc.co.uk/2/hi/science/nature/8631486.stm |title=BBC On-line: Clever New Caledonian crows can use three tools |work=BBC News |date=20 April 2010 |access-date=9 March 2013}}</ref><ref>{{Cite web|last=Baraniuk|first=Chris|date=12 December 2020|title=Crows could be the smartest animal other than primates|url=https://www.bbc.com/future/article/20191211-crows-could-be-the-smartest-animal-other-than-primates|access-date=31 August 2020|website=BBC}}</ref> Other corvids that have been observed using tools include: the [[American crow]], [[blue jay]], and [[green jay]]. Researchers have discovered that [[New Caledonian crow]]s do not just use single objects as tools—they can also construct novel compound tools through assemblage of otherwise non-functional elements.<ref>{{Cite journal|last1=Bayern|first1=A. M. P. von|last2=Danel|first2=S.|last3=Auersperg|first3=A. M. I.|last4=Mioduszewska|first4=B.|last5=Kacelnik|first5=A.|date=24 October 2018|title=Compound tool construction by New Caledonian crows|journal=Scientific Reports|volume=8|issue=1|page=15676|doi=10.1038/s41598-018-33458-z|pmid=30356096|issn=2045-2322|doi-access=free|pmc=6200727|bibcode=2018NatSR...815676B}}</ref><ref>{{Cite web|url=https://www.sciencealert.com/crows-are-so-smart-they-can-make-compound-tools-out-of-multiple-parts|title=Crows Can Build Compound Tools Out of Multiple Parts, And Are You Even Surprised|last=Starr|first=Michelle|date=25 October 2018|website=ScienceAlert|access-date=4 April 2020}}</ref> Diversity in tool design among corvids suggests cultural variation. Again, great apes are the only other animals known to use tools in such a fashion.<ref name = claytonemery2005 />

[[Clark's nutcracker]]s and [[jackdaw]]s were compared in a 2002 study based on geometric rule learning. The corvids, along with a [[domestic pigeon]], had to locate a target between two landmarks, while distances and landmarks were altered. The nutcrackers were more accurate in their searches than the jackdaws and pigeons.<ref name=Jones/>