News Columns & Blogs

Big final figures on least terns

This year's nesting 0f least terns in Wichita is officially over.Their success was absolutely fantastic.

Here's a summary compiled by Nathan Ofsthun of theGreat Plains Nature Center.

It has been copied from an online report with his permission.

"Below is a summary of the nesting colony of the federally endangeredInterior Least Terns in Wichita for 2010. These birds have been monitored byCharlie Cope (KDWP), Bob Gress (GPNC), and me (GPNC). The birds nested onone of the sandpits owned by LaFarge North America. We would like to expressour thanks and gratitude to the company for their willingness andcooperation in halting and adjusting their operations for 2 months. Ournesting colony of Least Terns enjoyed a secure and very productive year.

Least Terns were first observed in Wichita on 15 May at the convergence ofthe Big Ditch and the Arkansas River. Up to 12 adults were sighted until 29May. During this 2 week period, pair formation, fish flights, and severalcopulations were observed. Up to 6 terns were also seen on sandbars on theArkansas River immediately north of K-96. The terns disappeared from bothsites for several days until we received a call from the plant manager atLaFarge sandpits on 4 June. The terns had relocated to the site that theyhad chosen in 2009. An initial survey found 6 nests. By 8 June, a total of12 nests had been located with 2 or 3 eggs each. Heavy rains washed out 3 ofthe nests on 9 June, but on 15 June, 3 new nests were found and were assumedto be renests. By 20 June, 2 additional nests were located, bringing thetotal number of active nests to 14. On 21 June, the first chicks hatched; by30 June, a total of 22 chicks had hatched from the first 9 active nests. Anadditional nest with 3 eggs was found on 24 June (see fifth paragraph).Between 7 July and 13 July, 9 more chicks hatched. On 14 July, the latestobservation of renesting for the year was recorded. A single egg was foundin a scrape that was being incubated; however, the egg disappeared by 20July. Between 9 July and 30 July, a minimum of 25 chicks were observed tohave reached the fledgling stage.

A total of 19 nests were located this summer, although the greatest numberof active nests at one time was 15. A total of 50 eggs were laid of which 31hatched, 7 were flooded, and 12 were abandoned for unknown reasons. Of the31 chicks that hatched, 25 were known to have fledged, and 1 was found dead(probably Common Grackle predation). While we were never able to account forthe 5 "missing" chicks, it is more than possible that several flightedjuveniles left the nesting site or were concealed behind vegetation andterrain and were, accordingly, not counted. The highest count of adult LeastTerns was 30 (18 July); the average number of adults seen between 4 June and31 July was 24. Knowing that one adult in each respective pair was oftenaway fishing or at least not in the general area of its respective scrape, acount of 30 adults was exceptional knowing that no more than 15 nests wereactive at any one time during the season. Although there may have beentransient adults at any given time during the nesting season, 15 nests for ahighly monogamous species should theoretically equal 30 adults. In addition,1 first-summer Least Tern was observed between 14 June; 2 first-summer LeastTerns were sighted the following day; a single first-summer Least Tern wassubsequently seen until the end of the nesting season. In 2009, only 2chicks fledged from the Wichita site. Although we cannot say with certaintythat these were chicks that fledged from our site, we have reason to suspectthat the fidelity of one of the chicks to our site indicated that it mayindeed have been born at this Wichita site.

The range in days-to-hatch for our 31 eggs was 19 to 23 days (± 12 hours);the average was 20.1 days. This falls within the established rangenationwide. However, the established range in days-to-fledging is set at 19to 20+ days. Our range in days to fledging was 16 to 19 days (± 12 hours);the average was 17.9 days. It is perhaps notable to mention that 2 chickswas flighted on day 16; 4 chicks were flighted on day 17; 16 chicks wereflighted on day 18; and 3 chicks were flighted on day 19. Only 12% of ourchicks became flighted within the established range; the remainder were allflighted well before day 19.

Perhaps the most remarkable observation from this year involved a certainNest 18, which underwent a remarkable journey of survival. This nest wasquite accidentally discovered on 24 July; the nest, containing 3 eggs, waslocated in a bootprint that we had left behind on a previous survey. Duringthe heavy rains surrounding the Independence Day weekend, this nest waswashed away. The three eggs were carried 9 feet away from the originalscrape and embedded in the mud approximately 1.5 feet away from each other.These eggs were observed in this condition on two consecutive days and wereexposed to several heavy rains. A subsequent visit found the three mud-cakedeggs regrouped in a new pebble-lined scrape. We assumed that the eggs hadnot been incubated for a period of more than 36 hours, and our expectationswere low for this nest. However, we were most pleasantly surprised todiscover that two of the eggs hatched on time, and these chicks proceeded toreach the fledgling stage.

Another interesting observation was watching the combined effort of LeastTerns and Western Kingbirds in driving away a Red-tailed Hawk."