Editing Tree swallow (section)

===Feeding===
[[File:Tachycineta bicolor -Central New York, USA -flying-8.jpg|thumb|left|Flying in [[Central New York]], US]]
The tree swallow forages up to {{convert|50|m|ft}} above the ground singly or in groups. Its flight is a mix of flapping and gliding. During the breeding season, this is mostly within {{convert|4|km|mi}} of the nest site. When it is foraging for nestlings, though, it usually goes up to {{convert|200|m|ft}} from the nest,<ref name="hbw"/> mostly staying in sight of it, and forages at a height up to {{convert|12|m|ft}}.<ref name="McCartyWinkler1999">{{cite journal|last1=McCarty|first1=John P.|last2=Winkler|first2=David W.|title=Foraging ecology and diet selectivity of tree swallows feeding nestlings|journal=The Condor|volume=101|issue=2|year=1999|pages=246–254|issn=0010-5422|doi=10.2307/1369987|jstor=1369987|doi-access=free}}</ref> As well as being caught in flight,<ref name="Turner">{{cite book | last = Turner | first = Angela | title = A Handbook to the Swallows and Martins of the World | publisher = A & C Black | location = London | year = 2010 | isbn = 978-1-4081-3172-5 | pages = 97–100}}</ref> insects are sometimes taken from the ground, water, vegetation, and vertical surfaces.<ref name="hbw"/>

The tree swallow eats mostly insects, with some mollusks, spiders, and fruit. In North America, flies make up about 40% of the diet, supplemented with beetles and ants. Otherwise, the diet is about 90% flies.<ref name="hbw"/> The insects taken are a mix of aquatic and terrestrial organisms; the former are an important source of [[omega-3 fatty acid|omega-3 highly unsaturated fatty acid]]s. This is because, although the tree swallow can convert the precursor [[α-Linolenic acid]] into highly unsaturated fatty acids like [[docosahexaenoic acid]], it cannot do so in the quantities needed.<ref name="TwiningLawrence2018">{{cite journal|last1=Twining|first1=Cornelia W.|last2=Lawrence|first2=Peter|last3=Winkler|first3=David W.|last4=Flecker|first4=Alexander S.|last5=Brenna|first5=J. Thomas|title=Conversion efficiency of α-linolenic acid to omega-3 highly unsaturated fatty acids in aerial insectivore chicks|journal=The Journal of Experimental Biology|volume=221|issue=3|year=2018|pages=jeb165373|issn=0022-0949|doi=10.1242/jeb.165373|pmid=29217628|doi-access=free}}</ref> The seed and berry food is mainly from the genus ''[[Myrica]]'', which is mainly taken in all four of the Northern Hemisphere seasons except summer. Crustaceans were also found to be important in the wintering diet in a study on [[Long Island, New York]].<ref name="hbw"/>
[[File:Tree Swallow young and parent (14428436918).jpg|thumb|right|A chick being fed]]
Both sexes feed the nestlings (although the male feeds the chicks less than the females) resulting in about 10 to 20 feedings per hour.<ref name="hbw"/> The parents often use the chirp call to stimulate nestlings to beg. This is used more frequently with younger chicks, as they beg less than older chicks when the parent arrives with food but does not call.<ref name="LeonardFernandez1997">{{cite journal|last1=Leonard|first1=Marty L.|last2=Fernandez|first2=Nicole|last3=Brown|first3=Glen|title=Parental calls and nestling behavior in tree swallows|journal=The Auk|volume=114|issue=4|year=1997|pages=668–672|issn=0004-8038|doi=10.2307/4089286|jstor=4089286|doi-access=free}}</ref> The likelihood of begging in the absence of parents also increases with age.<ref name="LeonardHorn2001b">{{cite journal|last1=Leonard|first1=Marty L.|last2=Horn|first2=Andrew G.|title=Begging in the absence of parents by nestling tree swallows|journal=Behavioral Ecology|volume=12|issue=4|year=2001|pages=501–505|issn=1465-7279|doi=10.1093/beheco/12.4.501|doi-access=free}}</ref> The hatching order affects how much a chick is fed; last-hatched nestlings (in cases where hatching is asynchronous) are likely fed less than those hatched earlier.<ref name="JohnsonWimmers2003">{{cite journal|last1=Johnson|first1=L. Scott|last2=Wimmers|first2=Larry E.|last3=Campbell|first3=Sara|last4=Hamilton|first4=Lucy|title=Growth rate, size, and sex ratio of last-laid, last-hatched offspring in the tree swallow ''Tachycineta bicolor''|journal=Journal of Avian Biology|volume=34|issue=1|year=2003|pages=35–43|issn=0908-8857|doi=10.1034/j.1600-048X.2003.02950.x}}</ref> Nestlings closer to the entrance of the nest are also more likely to be fed, as are those who beg first<ref name="WhittinghamDunn2003">{{cite journal|last1=Whittingham|first1=Linda A|last2=Dunn|first2=Peter O|last3=Clotfelter|first3=Ethan D|title=Parental allocation of food to nestling tree swallows: the influence of nestling behaviour, sex and paternity|journal=Animal Behaviour|volume=65|issue=6|year=2003|pages=1203–1210|issn=0003-3472|doi=10.1006/anbe.2003.2178|s2cid=4993059}}</ref> and more frequently. The overall rate at which a brood is fed also increases with more begging.<ref name="LeonardHorn2001">{{cite journal|last1=Leonard|first1=M. L.|last2=Horn|first2=Andrew G.|title=Begging calls and parental feeding decisions in tree swallows (''Tachycineta bicolor'')|journal=Behavioral Ecology and Sociobiology|volume=49|issue=2–3|year=2001|pages=170–175|issn=0340-5443|doi=10.1007/s002650000290|bibcode=2001BEcoS..49..170L |s2cid=25507198}}</ref> The diet itself is composed mostly of insects, those in the orders [[Diptera]], [[Hemiptera]], and [[Odonata]] making up most of the diet.<ref name="hbw"/> These insects are mostly up to {{convert|10|mm|in|abbr=on}} in size, but sometimes are up to {{convert|60|mm|in|abbr=on}} in length.<ref name="McCartyWinkler1999"/> In nests near lakes [[Freshwater acidification|acidified]] by humans, calcium supplements, primarily fish bones, crayfish [[exoskeleton]]s, clam shells, and the shells of bird eggs, are harder to find. This forces the adult tree swallow to travel further than usual—sometimes up to {{convert|650|m|ft|abbr=on}} away from the nest—to get these calcium supplements.<ref name="St. LouisBreebaart1991">{{cite journal|last1=St. Louis|first1=Vincent L.|last2=Breebaart|first2=Loes|title=Calcium supplements in the diet of nestling tree swallows near acid sensitive lakes|journal=The Condor|volume=93|issue=2|year=1991|pages=286–294|issn=0010-5422|doi=10.2307/1368944|jstor=1368944|s2cid=87271779 }}</ref>