{"id":10764,"date":"2011-06-20T01:33:56","date_gmt":"2011-06-20T00:33:56","guid":{"rendered":"https:\/\/communicatescience.com\/zoonomian\/?p=10764"},"modified":"2011-06-21T15:26:35","modified_gmt":"2011-06-21T14:26:35","slug":"ducks-per-second-a-most-useful-unit-of-velocity","status":"publish","type":"post","link":"https:\/\/communicatescience.com\/zoonomian\/2011\/06\/20\/ducks-per-second-a-most-useful-unit-of-velocity\/","title":{"rendered":"Ducks per Second: A Most Useful Unit of Velocity"},"content":{"rendered":"
\"\"<\/a>
Figure 1 - Sand Martin approaches from rear of convoy<\/figcaption><\/figure>\n
\"\"<\/a>
Figure 2 - Sand Martin passes over second duck in convoy<\/figcaption><\/figure>\n

When I lived in the Midlands of the UK, away from the bussle of London’s controlled airspace, one of my pleasures on an evening was to hire a light aircraft at my local airfield and tootle off for an hour or so practicing maneoveurs and generally enjoying the sunset – all very peaceful.<\/p>\n

Except, one evening when I was out tootling above the Cotswolds; like a flash, an RAF Tornado jet whooshed from under me, matching my track but far exceeding my speed, and all uncomfortably close – a disappearing dot before I could blink.<\/p>\n

In fact, he was probably a good 500 ft below me and certainly had on-board radar – so nothing actually dangerous going on. (There’s a popular myth\u00a0 – that may be true – that on such occasions the military use light aircraft for practice interception.)<\/p>\n

Anyhow, it made an impression on me, and today the memory returned unbidden with these two photographs snapped at the Rick Pond in Hampton Court Park.\u00a0 They show a Sand Martin in a low-level, high speed pass over a convoy of ducklings – as bemused, no doubt, as I was 4000 feet above the Cotswolds (Figs 1 & 2).<\/p>\n

\"\"<\/a>
Low-flying Sand Martin (Riparia riparia) with Mallards<\/figcaption><\/figure>\n

I’d been trying to catch the Martins’ aerobatic fly-catching with no success, and started snapping the ducks more as a gesture of resigned failure. I only spotted the Martin when I downloaded the flash card.<\/p>\n

This type of ‘buzzing’ seems to be in the Sand Martin’s nature. People on the bank get similar treatment – the bird coming from behind, passing within inches of heads, as if honing their own targeting systems.<\/p>\n

I’d left the camera in rapid fire mode of 8 fps, so the time interval between the two photographs is known.\u00a0\u00a0 If we also know the length of a duck, we can calculate the Martin’s speed, in ducks per second –\u00a0 or more tedious conventional units. \u00a0 So:<\/p>\n

Assuming SML = 0.3m\u00a0 (Standard Mallard Length)<\/p>\n

Time between pictures at 8 f.p.s = 0.125 s<\/p>\n

Ducks passed between frames = 5.75 (use the grid to measure; one duck = 2 grid squares)<\/p>\n

Bird Velocity = (5.75\/0.125) = 46 ducks \/ second<\/strong><\/span> (Systeme Canard)<\/p>\n

or\u00a0 (46×0.3)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 = 13.8 metres \/ second<\/strong><\/span> (SI)<\/p>\n

0r\u00a0 (13.8×2.24)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 = 31 m.p.h.<\/strong><\/span><\/p>\n

There we have it.\u00a0 Hugely practicable and useful method for measurement of the velocity of birds over water \ud83d\ude42<\/p>\n

And this is quite possibly where the Sand Martins live.\u00a0 A short hop at 31 mph.<\/p>\n

\"\"<\/a>
Eel Pie Island Sand Martin Bank (Photo: Tim Jones)<\/figcaption><\/figure>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

When I lived in the Midlands of the UK, away from the bussle of London’s controlled airspace, one of my pleasures on an evening was to hire a light aircraft at my local airfield and tootle off for an hour or so practicing maneoveurs and generally enjoying the sunset – all very peaceful. Except, one … Continue reading Ducks per Second: A Most Useful Unit of Velocity<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"ngg_post_thumbnail":0,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[4,175,567,568,1151],"tags":[1425,1189,1191,1188,1190],"class_list":["post-10764","post","type-post","status-publish","format-standard","hentry","category-animals","category-biology","category-experiments","category-fun","category-ornithology","tag-duck","tag-measurement","tag-rick-pond","tag-sand-martin","tag-velocity"],"aioseo_notices":[],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pkpOr-2NC","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/communicatescience.com\/zoonomian\/wp-json\/wp\/v2\/posts\/10764","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/communicatescience.com\/zoonomian\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/communicatescience.com\/zoonomian\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/communicatescience.com\/zoonomian\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/communicatescience.com\/zoonomian\/wp-json\/wp\/v2\/comments?post=10764"}],"version-history":[{"count":51,"href":"https:\/\/communicatescience.com\/zoonomian\/wp-json\/wp\/v2\/posts\/10764\/revisions"}],"predecessor-version":[{"id":10820,"href":"https:\/\/communicatescience.com\/zoonomian\/wp-json\/wp\/v2\/posts\/10764\/revisions\/10820"}],"wp:attachment":[{"href":"https:\/\/communicatescience.com\/zoonomian\/wp-json\/wp\/v2\/media?parent=10764"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/communicatescience.com\/zoonomian\/wp-json\/wp\/v2\/categories?post=10764"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/communicatescience.com\/zoonomian\/wp-json\/wp\/v2\/tags?post=10764"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}