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Nighthawks v Nightjars

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Old Monday 29th June 2020, 11:38   #1
KenM
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Nighthawks v Nightjars

Whilst in the USA last year Oregon to be more precise, I got a life tick in the shape of a Common Nighthawk, in direct sunlight late afternoon flying over a belt of pines.
It occurred to me that Nighthawks unlike Nightjars can not infrequently be seen during the day sometimes over fresh water where it has been noted that they can flock particularly before migration Aug/Sep.

I have to assume that this behaviour has not ever been recorded in the Old World for Eurasian Nightjars, thus am wondering what might drive this behavioural difference?

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Old Monday 29th June 2020, 13:55   #2
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Completely different forging strategy, reflected in their wing shape. Nighthawks are superb at aerial maneuvering, as they chase flying insects. If it is a cloudy day, and insects are flying low, they will often be up foraging well before dark. Other caprimulgids have blunter wings and I imagine are more ambush predators,as they fly low through forests, shrublands, or even deserts. Hard to be an ambush predator when it is light.

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Old Monday 29th June 2020, 14:59   #3
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Nightjars do most of their hunting actually while there is some light (ie dawn and dusk). They will hunt well into the night if there’s a full moon (or round artificial lighting) . I suspect their crepuscular foraging habits are largely due to a combination of visual limitations and diet preferences (about 80-90% of their biomass is from nightime flying moths and beetles) rather than for reasons of stealth (how aware are moths and beetles of a large open gape flying towards them?!) - They also prefer foraging in forests with open areas of heath or young growth rather than older dense pine plantations. (I don’t know enough about Nighthawks to compare their ecological niche with European Nightjar, so cant comment on that). As for wing shape, birds that have more pointed wings tend to be the ones to spend the most time arial foraging and at greater heights - European Nightjars forage low (head height often) and land frequently which might explain difference in wingtip shape between the two sp.
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Old Monday 29th June 2020, 15:24   #4
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Completely different forging strategy, reflected in their wing shape. Nighthawks are superb at aerial maneuvering, as they chase flying insects. If it is a cloudy day, and insects are flying low, they will often be up foraging well before dark. Other caprimulgids have blunter wings and I imagine are more ambush predators,as they fly low through forests, shrublands, or even deserts. Hard to be an ambush predator when it is light.

Andy
Yes, thanks Andy, It was the behavioural differences on migration and diurnal activity over freshwater water which caught my imagination, ie in the old world I believe the “flocking” example and hunting during the day does not occur, thus this is what appeals as opposed to the latter.

Eurasian Birder’s are fortunate indeed to ever witness any of the Nightjar species during daylight hours, except perchance by unwittingly disturbing them on the ground, then swiftly away ne’er to be seen again. Yes they’re all Caprimulgidae and are in the main crepuscular certainly in the Old World but not quite so in the New.
Wonder what it is that makes Nighthawks more gregarious and diurnal as opposed to Nightjars across the pond which at best arrive and depart singly under the cloak of darkness...same family, predating the same food supply, adopting the same Wintering strategy (Common Nighthawk only) yet with different behavioural patterns. Interesting that Nighthawks appear to enjoy a “longer”night and a more “social“ migration.

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Old Tuesday 30th June 2020, 00:36   #5
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I'd suspect predation risks might also be significant for keeping Nightjars nocturnal - they are slower fliers than Nighthawks, so easier for a raptor to catch in good light. I remember reading that predation risk is the major driver for keeping bats nocturnal; day-flying bats don't have good life chances, and the same could apply to Nightjars.
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Old Tuesday 30th June 2020, 05:29   #6
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I'd suspect predation risks might also be significant for keeping Nightjars nocturnal - they are slower fliers than Nighthawks, so easier for a raptor to catch in good light...
Yes, as I was typing “European Nightjars forage low ...and land frequently”, that also occurred to me.

When one actually starts to put some thought to it, ‘nature’ seems to have an intrinsic logic not always apparent to the casual observer!
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Old Tuesday 30th June 2020, 06:23   #7
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Acknowledging the force of all that has been said, I saw my first migrating Nightjar come in-off at Selsey Bill this spring, which was very nice and in broad daylight. At the speed it was going I suspect it had set off over the Channel in daylight though that doesn't mean it hadn't flown all night.

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Old Tuesday 30th June 2020, 08:24   #8
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I'd suspect predation risks might also be significant for keeping Nightjars nocturnal - they are slower fliers than Nighthawks, so easier for a raptor to catch in good light. I remember reading that predation risk is the major driver for keeping bats nocturnal; day-flying bats don't have good life chances, and the same could apply to Nightjars.
Yes Nutty thanks, Nightjars would appear to be less “speedy” than Nighthawks due to evolved shape and size, which may well explain their would be vulnerability during any diurnal movements albeit as John points out below, there may well be exceptions to this behaviour when needs must, perhaps taking advantage of weather conditions particularly when migrating?

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Acknowledging the force of all that has been said, I saw my first migrating Nightjar come in-off at Selsey Bill this spring, which was very nice and in broad daylight. At the speed it was going I suspect it had set off over the Channel in daylight though that doesn't mean it hadn't flown all night.
John
I envy you that experience John must have been a sight to behold. Circa ten years ago I was hunting Woodcock (with bins) post sunset in a local area, when I heard what I initially (at distance) thought was an old motorbike, which then morphed into a “faint” churring followed by the manifestation itself! just a few metres ahead of me in total silhouette. I can say to this day that being so close and able to appreciate the “buoyancy of flight” was mesmerising and left me thinking of how it might have looked in broad daylight.

It might be of interest reading from Birds of Cyprus (David and Mary Bannerman) an extract written April 30th 1954 driving Eastwards at night along the high road between Lefkoniko and Kantara a distance of twelve miles, they counted sixty eight individuals (of which half were males), I suppose that might be called a” loose flock” or “social distancing”, wonder if those numbers could be relied upon today?

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Old Tuesday 30th June 2020, 09:08   #9
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... I can say to this day that being so close and able to appreciate the “buoyancy of flight” was mesmerising and left me thinking of how it might have looked in broad daylight.
Cheers
My first close encounter with a Nightjar was about 40 years ago in the Ashdown Forest with a group of school friends - we were walking quickly back to the minibus just after sundown (so still light) and I was flapping away midges with a beige-white bush hat - suddenly I heard a strange clicking near my ear and a Nightjar started circling round my head. Many Nightjars and years later, having held them in the hand and looked at them closely with a head torch, I can honestly say they are stunning birds (with ridiculously tiny feet!)
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Old Tuesday 30th June 2020, 09:55   #10
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I envy you that experience John must have been a sight to behold. Circa ten years ago I was hunting Woodcock (with bins) post sunset in a local area, when I heard what I initially (at distance) thought was an old motorbike, which then morphed into a “faint” churring followed by the manifestation itself! just a few metres ahead of me in total silhouette. I can say to this day that being so close and able to appreciate the “buoyancy of flight” was mesmerising and left me thinking of how it might have looked in broad daylight.

It might be of interest reading from Birds of Cyprus (David and Mary Bannerman) an extract written April 30th 1954 driving Eastwards at night along the high road between Lefkoniko and Kantara a distance of twelve miles, they counted sixty eight individuals (of which half were males), I suppose that might be called a” loose flock” or “social distancing”, wonder if those numbers could be relied upon today?

Cheers
It was quite a sight. Later, I wondered why I didn't jump up and run round the corner from the seawatching crowd to see if the bird had pitched, but one can't think of everything (and "jumping up" is more laborious than it used to be!)

My calculator says the Birds of Cyprus figures amount to one Nightjar every 300 yards which if only half were males means a pair every 600 yards: which doesn't sound like any flock I've ever seen!

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Old Tuesday 30th June 2020, 10:10   #11
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My first close encounter with a Nightjar was about 40 years ago in the Ashdown Forest with a group of school friends - we were walking quickly back to the minibus just after sundown (so still light) and I was flapping away midges with a beige-white bush hat - suddenly I heard a strange clicking near my ear and a Nightjar started circling round my head. Many Nightjars and years later, having held them in the hand and looked at them closely with a head torch, I can honestly say they are stunning birds (with ridiculously tiny feet!)
Interesting account Deb! I seem to recall reading an article somewhere of an individual’s downward “whipping” (up and down) of a white handkerchief could attract any local males that were holding territory nearby.
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Old Tuesday 30th June 2020, 10:23   #12
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Don't forget Nighthawks are not 'just' an equivalent to Nightjar but on the other side of the Atlantic. There are also a number of other nightjars in the US, different habitats, niches etc. Interesting subject.
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Old Tuesday 30th June 2020, 10:42   #13
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Don't forget Nighthawks are not 'just' an equivalent to Nightjar but on the other side of the Atlantic. There are also a number of other nightjars in the US, different habitats, niches etc. Interesting subject.
A very fair point and you have to wonder if Common Nighthawk is not actually the best fit comparator to European Nightjar out of the array of Caprimulgiforms found across the continent of North America in the breeding season? Europe in general seems to suffer a paucity of nightjar species compared to North America though further South, Africa is well provided.

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Old Tuesday 30th June 2020, 12:35   #14
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Interesting account Deb! I seem to recall reading an article somewhere of an individual’s downward “whipping” (up and down) of a white handkerchief could attract any local males that were holding territory nearby.
True Ken! I think it may be related to the white spotlights on the outer retrices of the males and on their wingtips - in flight (in low light) the wing spots stand out like beacons so a white hanky or such may perhaps initiate a defensive intruder male alert behavior?

Doing some background reading (in between actually doing some work online!), notwithstanding the ‘oranges and lemons’ here viz a viz being different species, CONI do seem to have a wider ecological niche in terms of habitat preference/scales of availability/food selection and foraging behavior than E.Nightjar but still suffer the similar pressures of predation and habitat loss so perhaps when it comes to daytime foraging, necessity being the mother of invention? Like all aerial insectivores (including hirundines) are also impacted by local weather factors and wider climatic impacts on insect populations (including in African/American pitstops on migration) so probably more in common than divides them when it comes to understanding ecological pressures of both sp. https://core.ac.uk/download/pdf/217184773.pdf
https://ftp-public.abmi.ca/home/publ...sBird_ABMI.pdf
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Old Tuesday 30th June 2020, 15:12   #15
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A very fair point and you have to wonder if Common Nighthawk is not actually the best fit comparator to European Nightjar out of the array of Caprimulgiforms found across the continent of North America in the breeding season? Europe in general seems to suffer a paucity of nightjar species compared to North America though further South, Africa is well provided.

John
Yes John, I used Com.Nighthawk as a comparative because of it’s Wintering range perhaps more comparable to European Nightjar ie similar distances travelled between Breeding/Wintering areas as compared to the other NA Goatsuckers.
Quite right regarding the NA Caprimulgus being more nocturnal like EN. Interestingly of the other four species of NA Caps., which overwinter in California/West and SE.Texas and Florida, which would put them on the same latitude as the Canaries, whereas EN would be Wintering much further South.

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Old Tuesday 30th June 2020, 23:31   #16
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Fascinating discussion!

I've seen actively migrating nighthawks associated with nocturnal movement twice over my yard. Most observations are of birds that are migrating in late afternoon, casually flapping towards their destination while stopping to catch insects at times. One morning last fall, I picked out a bird not long after sunrise that was ridiculously high, too far for the naked eye! Surely a bird that was migrating all night. Then this spring, I observed multiple nighthawks at similar altitude a little before sunset. They were pushed along by a strong SW wind and again were incredibly high!

Point being, nighthawks undoubtedly reach respectable heights during nocturnal migration. I'd be fascinated to know how high Whippoorwills and (European) Nightjars fly during nocturnal migration. Surely lower???
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Old Wednesday 1st July 2020, 15:44   #17
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Fascinating discussion!
Point being, nighthawks undoubtedly reach respectable heights during nocturnal migration. I'd be fascinated to know how high Whippoorwills and (European) Nightjars fly during nocturnal migration. Surely lower???
Earlier this Spring (believe late May), a Nightjar’s wing was found in the City of London on the sidewalk, (believed to have been a Peregrine victim). Would presume that it was taken at a sufficient height to clear the talk buildings perhaps 4-500’ as I believe Peregrine might just prefer taking potentially more agile victims higher up, rather than lower down?

Further to this incident, several years ago in Central Park (mid-day in May) I was shown a Chuck-will’s widow resting partially undercover at ground level, which presumably entered NYCity’s canyon-ed air space from a relatively high elevation before descending down into cover?

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Old Wednesday 1st July 2020, 16:44   #18
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Earlier this Spring (believe late May), a Nightjar’s wing was found in the City of London on the sidewalk, (believed to have been a Peregrine victim). Would presume that it was taken at a sufficient height to clear the talk buildings perhaps 4-500’ as I believe Peregrine might just prefer taking potentially more agile victims higher up, rather than lower down?

Further to this incident, several years ago in Central Park (mid-day in May) I was shown a Chuck-will’s widow resting partially undercover at ground level, which presumably entered NYCity’s canyon-ed air space from a relatively high elevation before descending down into cover?

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There are no sidewalks in the City of London, and you would be pushed to find one in England unless there is one at Elstree studios!

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Old Wednesday 1st July 2020, 18:21   #19
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There are no sidewalks in the City of London, and you would be pushed to find one in England unless there is one at Elstree studios!

John
It was aimed at birdmeister, unsure what pavement means in the US?
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Old Wednesday 1st July 2020, 18:31   #20
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It was aimed at birdmeister, unsure what pavement means in the US?
Pavement in the US can mean the road surface. No reason to use other than English English about London though.

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Old Wednesday 1st July 2020, 21:23   #21
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Thanks for the response Ken and John, just a brief brush-up with the terminology for a minute.


I'd forgotten about the whole Central Park scene, didn't realize a Chuck has been there (should have figured!). I imagine they fly at moderate height, but I guess it's hard to tell for sure.
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Old Wednesday 1st July 2020, 21:47   #22
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Fascinating discussion!

I've seen actively migrating nighthawks associated with nocturnal movement twice over my yard. Most observations are of birds that are migrating in late afternoon, casually flapping towards their destination while stopping to catch insects at times. One morning last fall, I picked out a bird not long after sunrise that was ridiculously high, too far for the naked eye! Surely a bird that was migrating all night. Then this spring, I observed multiple nighthawks at similar altitude a little before sunset. They were pushed along by a strong SW wind and again were incredibly high!

Point being, nighthawks undoubtedly reach respectable heights during nocturnal migration. I'd be fascinated to know how high Whippoorwills and (European) Nightjars fly during nocturnal migration. Surely lower???
The one I saw come in off the sea was at wavetop height. But that was daylight, so there may have been intent to sneak through low down and unseen by any passing falcons. It was moving at some considerable speed, as well: watching them floating about lowland heath churring doesn't give a real impression of their flight capabilities.

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Old Wednesday 1st July 2020, 23:46   #23
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Another difference, as far as I'm aware:

Nighthawks are frequently urban birds, and will often nest on flat rooftops (I think? Is that correct?)

Nightjars - in UK at least - very strictly avoid human habitation, only occurring on wilder heathlands and conifer plantation clearfell sites.
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Old Thursday 2nd July 2020, 08:00   #24
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The one I saw come in off the sea was at wavetop height. But that was daylight, so there may have been intent to sneak through low down and unseen by any passing falcons. It was moving at some considerable speed, as well: watching them floating about lowland heath churring doesn't give a real impression of their flight capabilities.

John
.....mmm so there's at least two gears in the gearbox.
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Old Thursday 2nd July 2020, 16:24   #25
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European Nightjars and many other nightjars, hunt from a low branch or from the ground most of the time. They take off like flycatchers and land back. You see it during spotlighting.

Nocturnal they are, but now, during the longest midsummer days, European Nightjars are active well before it is dark. As many other nocturnal animals, out of necessity.

Nighthawks are better flyers, so probably less afraid of birds of prey and more keen to hunt over open water.
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