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IntroductionIn the late afternoon of 12 May 2017, Iwas observing a multi-compartment nestbox complex in Leamington, Ontario(Figure 1). This artificial structure wasoccupied by multiple breeding pairs ofboth Purple Martin (Progne subis) andHouse Sparrow (Passer domesticus). Whilestudying the activities of these birds at thehouse, I noticed that a bird’s right wingwas protruding from one of the entranceholes; the wing was stationary and itsentire length from the carpal joint to thetips of the primaries was visible (Figures1, 2). Owing to its suspended appearanceand angle within the entrance, itappeared to be attached to a body. Mostof the hole’s right half was occluded bynest material consisting of dried grassstalks, which emanated from the hole

(Figures 1, 2); it was not possible to seeany more of a presumed bird inside.Based on the appearance of the wing andthe fine nesting material as well as thecurrent occupancy of the housing com-plex, I deduced that the wing mustbelong to a Purple Martin and that thenest inside had been constructed byHouse Sparrows. Purple Martin nestsgenerally contain coarser dried vegetationthat is deposited neatly within the cavity;if it projects from the cavity, it does so atthe bottom of the hole, not along thesides, and is mixed with mud (pers. obs.)(Figure 3). The wing was not presentwhen I observed the nest box complexapproximately 24 hours prior, on 11 May2017. I requested and received permis-sion from the property owner to conducta hands-on investigation.

Purple Martin deathby entrapment in aHouse Sparrow nestJustin Peter

Figure 1. Multi-compartment nest boxcomplex in Leamington, Ontario.Photo: Justin Peter

44 Ontario Birds April 2019

On 15 May 2017, the wing was stillpresent and I used a ladder to gain accessto the exterior of the compartment. Iattempted to flex and extend the wing ofthe bird and I palpated just inside thecompartment entrance to the base of thewing, determining that the wing wasindeed attached to a body. The body’sright side was positioned lengthwisealong the compartment’s front insidewall with the head lower than the bird’srear. The grass stalks in the entrance holeobscured the bird’s head, which waswedged within them. I extracted the birdfrom the cavity (Figure 4). The bird wasa dead adult (after second-year) femalePurple Martin (Hill 2002). Its head was

cocked to the left and its tail featherswere bent towards the bird’s right side.In addition, its vent feathers were soiledby feces (Figure 5). It had dabs of feceson its central breast feathers as well andhad two poultry feathers adhering to itsunderside. Its right leg was extendedwith toes partly flexed, and the left footwas in a perching position with the toesextended. The bird did not have anyobvious signs of external trauma. Basedon the position of the right leg, it appearsthat the bird was attempting to thrustitself forward. Is it possible that this mar-tin died due to its inability to exit thecavity?

Figure 2. Purple Martin wing protruding from nest compartment entrance, attached to a body entangledin the grass of a House Sparrow nest. Photo: Justin Peter

Figure 3. Nest compartment in multi-cavity complex with a typical Purple Martin nest,showing coarse materialsmixed with mud spilling out of the compartment.

Figure 4. Female Purple Martin extracted from thenest compartment. Grassesextruding from the entrancehole had obscured the bird’shead, which was wedgedwithin them.Photos: Justin Peter

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The House and Nest CompartmentsThe house contained 18 compartments.The complex’s compartment entranceholes were approximately 5 cm in diam-eter. Based on this dimension, I estimat-ed a cavity’s interior dimensions to beapproximately 15 cm x 15 cm x 15 cm. Iwas curious about the configuration ofthe nest within the compartment in ques-tion. By probing through the cavityentrance, I determined that the bottomof the nest compartment was paddedwith grass stalks. There were a couple oflarge poultry-like feathers embedded inthe stalks just inside the entrance, and thegrassy materials reduced the apparent

diameter of the entrance by approxi-mately 50%. Just inside the entrance,materials were arranged in such a waythat formed a tunnel that veered towardsthe left, obscuring the rear wall of thecavity. Presumably, the tunnel met thecompartment’s left wall and led to a rearchamber where a nest cup would be sit-uated. The copious use of grass stalksdressed over the walls and roof in a waythat could form a tunnel-like structurewas consistent with construction byHouse Sparrows (Harrison 1975, Indy -kiewicz 1991, Lowther and Cink 2013).Based on this, it appeared that the Pur-ple Martin had entered a House Sparrow

Figure 5. Female Purple Martin extracted from nest compartment with its head cocked to the bird’s leftand tail feathers bent towards its right side. Note vent feathers soiled by feces. Photo: Justin Peter

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nest, which may or may not have beenactive. The orientation of the materialswithin the compartment would have pre-vented the martin from moving straighttowards the rear wall after entering, andwould also have prevented her from exit-ing the compartment by directly facingthe entrance hole.

I observed the activity of birds at thehouse for approximately 15 minutes fol-lowing the removal of the dead bird.Four compartments were being attendedby after-second year (i.e., in definitivebasic plumage) Purple Martin males andcontained nests typical for this species.Six units were attended by House Spar-rows and contained nest material withcopious grass stalks typical of thatspecies. Additional compartmentsappeared unoccupied but all containedHouse Sparrow-type nests, including thecompartment that is the subject of thisnote. It is unknown whether theensnared female Purple Martin had beeninvestigating the nest cavity with designson appropriating it.

DiscussionThere is a paucity of records of bird deathdue to entrapment in nests; however,there are instances of death at nest sitesthat appear related to competition or pre-dation. An Eastern Bluebird (Sialia sialis)died after being stuck to the pine resinoozing around the nest cavity hole of aRed-cockaded Woodpecker (Picoidesborealis), presumably as the bluebird wasinvestigating the cavity as a potential nestsite (Dennis 1971). A Steller’s Jay (Cyan -ocitta stelleri) was ensnared by fishing linethat had been incorporated into the nestof a Bullock’s Oriole (Icterus bullockii)

possibly as the jay was investigating thenest for potential prey in the form of eggsor nestlings (Iron and Pittaway 1995).

The Purple Martin is a secondary-cavity nester and its eastern populationbreeds almost exclusively in artificialmulti-compartment nest box complexesclose to humans, effectively formingcolonies in such places (Brown and Tarof2013). Both males and females maydefend multiple cavities against con-specifics of the same sex, at least early inthe breeding season. In unmanagedcolonies, Purple Martins may competewith introduced House Sparrows, which— while not obligate cavity nesters —take readily to artificial cavities and mayalso breed in loose aggregations in suchplaces (Jackson and Tate 1974, pers.obs.). A House Sparrow nest built with-in an enclosed space may be a mere cupof vegetation at the bottom of the com-partment or may be built up so that nestmaterial covers sides as well as top of nestbox chamber (Indykiewicz 1991),expanding to fill the available volume(Lowther and Cink 2013). Withouthuman intervention and management ofmartin nest box complexes, sparrowsmay cause the local extirpation of mar-tins by appropriating nest cavities andmaking them permanently unsuitable formartin use (Brown and Tarof 2013); thismay be due to the obstructive nature ofthe nest itself. However, Purple Martinssometimes appropriate a compartmentthat contains a partly built House Spar-row nest, using grass placed by sparrowsas base for their nest; these nests maycontain feathers brought in by sparrows,which martins do not try to discard(Brown and Tarof 2013).

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A Purple Martin’s total length is 20cm whereas a House Sparrow’s length is16 cm (Dunn and Alderfer 2017). Giventhe compartment’s actual dimensions andthe reduction in effective accessible spacedue to the presence of the House Sparrownest as well as the orientation of the mate-rials, the Purple Martin’s maneuverabili-ty within the compartment would havebeen compromised. Furthermore, theposition of the victim’s head, buried as itwas in the grass stalks that partly blockedthe entrance hole, suggests that the reduc-tion in the hole diameter was also a fac-tor in the martin’s death. Whereas a spar-row’s nest, filling a compartment as itmay, might ordinarily outright repel aPurple Martin or other larger birds, thevictim in this instance made a fatal mis-take by entering but not being able to exitthe compartment. The soiled vent inaddition to the position of the martin’slegs and bent tail feathers suggest that thebird became stuck in attempting to exitthe compartment but was unable toprogress, and that the style of HouseSparrow nest presented an obstacle to hermovement. This is the first known recordof a Purple Martin death by entrapmentin a House Sparrow nest.

Acknowledgements

I would like to thank the property ownerfor allowing me access to the nest box,Sarah Rupert for lending me a ladder,Ron Pittaway and Jean Iron for assistancewith the literature, Jamie Hill III for con-firming the specimen’s age and to thereviewers for helpful comments on anearlier draft.

Literature CitedBrown, C.R. and S. Tarof. 2013. Purple Martin (Progne subis), version 2.0. In TheBirds of North America Online (A. F. Poole,Editor). Cornell Lab of Ornithology, Ithaca, New York. https://doi.org/10.2173/bna.287

Dennis, J.V. 1971. Species using Red-cock -aded Woodpecker holes in NortheasternSouth Carolina. Bird-Banding 42:79-87.

Dunn, J.L. and J. Alderfer. 2017. NationalGeographic Field Guide to the Birds of North America, Seventh Edition. NationalGeographic, Washington D.C. 591 pp.

Harrison, H.H. 1975. Peterson Field Guide:Eastern Birds' Nests. Houghton Mifflin Company New York, New York. 257 pp.

Hill, J.R., III. 2002. Tattletails: How to tellthe sex and age of Purple Martins by theirundertail coverts. Purple Martin Update11:16-17.

Indykiewicz, P. 1991. Nests and nest-sites of the House Sparrow Passer domesticus(LlNNAEUS, 1758) in urban, suburban and rural environments. Acta zoologica cracoviensis 34:475-495.

Iron, J. and R. Pittaway. 1995. Caught inthe act — Steller’s Jay killed robbing NorthernOriole nest. Birders Journal 4:90-91.

Jackson, J.A. and J. Tate, Jr. 1974. An analy-sis of nest box use by Purple Martins, HouseSparrows and Starlings in eastern NorthAmerica. Wilson Bulletin 86:435-449.

Lowther, P.E. and C.L. Cink. 2013. HouseSparrow (Passer domesticus), version 2.0. In The Birds of North America Online (A. F. Poole, Editor). Cornell Lab of Orni -thology, Ithaca, New York. https://doi.org/10.2173/bna.12

Justin Peter491 King Street EastToronto, Ontario M5A 4l1E-mail: jbpetr@yahoo.ca