Tom Stehn, Whooping Crane Coordinator
U.S. Fish and Wildlife Service
Aransas National Wildlife Refuge

Tom Stehn's Whooping Crane Report - February 1, 2010

The fifth aerial census of the 2009-10 whooping crane season was conducted January 21, 2010 in a Cessna 210 piloted by Gary Ritchey of Air Transit Solutions of Castroville, Texas with USFWS observer Tom Stehn.  Sighted on the flight were 235 adults and 18 juveniles = 253 total whooping cranes.  This was 10 birds less than the last flight conducted 1-05-10.  However, flight time was limited by fog that did not burn off until 10:30 AM, so some cranes were presumably overlooked, as search time had to be condensed.  More telling than the total number of cranes tallied was the distribution observed that seemed to confirm the estimated flock size.  However, it definitely appears that one juvenile has died since arriving at Aransas.  This juvenile had been found in the refuge’s South Sundown Island territory.  On today’s flight, a pair believed to be the S. Sundown Island pair was seen very close to their territorial neighbors to the south.  It seemed clear that I was looking at adjacent territorial pairs, and that the S. Sundown Island pair was missing its chick.  It is also possible that the Dewberry Island pair at Welder’s Flats has lost their chick, but it is also possible they had moved over to the refuge’s Power Lake on Matagorda Island where there was an unexpected family. 

The territories of adult cranes remain difficult to figure out as many of the crane pairs have left their marsh and are searching for food on the uplands.  On today’s flight, an unusually high 52 cranes were on unburned uplands, 4 were on the C14 refuge burn, 13 were in open bays, two were at a game feeder south of the Big Tree on Lamar, and 182 (72%) were in salt marsh.  Blue crabs are at extremely low levels and the cranes are having to look for other sources of food.  This is a very stressful time of winter for the whooping cranes.  One additional juvenile that apparently separated from its parents during migration was sighted near Medford, Oklahoma December 14-25 has not been re-sighted but is presumably doing okay in an unknown location.

The flock size is currently estimated at 244 adults + 19 juveniles = 263.

January 21st - Recap of whooping cranes (253) found at Aransas:

 *   The presence of one chick last seen in Oklahoma makes the current estimated flock size 263, including 19 chicks.  One chick has died since arriving at Aransas. 

One whooping crane was sighted on 1/17/10 by a TPWD biologist on the Smith Marsh in Matagorda County. The Smith Marsh is private property just to the west of the Nature Conservancy's Mad Island Marsh Preserve a considerable ways up the coast from Aransas.

Flight Conditions:  Visibility was excellent throughout the flight, though the sun angle on late afternoon transects made for difficult viewing conditions when heading into the sun.  Winds were light and flight conditions were smooth, enabling us to travel at approximately 130 knots for most of the flight.  Due to reported crane movements, the search area was expanded much further out into upland areas.  However, only three additional cranes were found in the uplands at Welder Flats, whereas 12 had been located there the previous week.  This difference seemed to account for the 10 fewer cranes found on today’s flight compared to the previous flight.  In addition, no cranes were found at the refuge’s Burgentine Lake, whereas seven had been present on the previous flight.  The largest group size observed was seven birds seen on the uplands on San Jose and in the marsh on Matagorda Island. 

      Tom Stehn                                    

TOM STEHN'S LAST WHOOPING CRANE REPORT: JANUARY 18, 2010

The fourth aerial census of the 2009-10 whooping crane season was conducted January 5, 2010 in a Cessna 210 piloted by Gary Ritchey of Air Transit Solutions of Castroville, Texas with USFWS observer Tom Stehn.  Sighted on the flight were 244 adults and 19 juveniles = 263 total.  This was an increase of 19 cranes since the previous flight conducted December 10th when some birds had still been in migration and 244 cranes were accounted for.  One additional juvenile separated from its parents was sighted near Medford, Oklahoma  December 14-25 which brings the current estimated flock size to 264.  In addition, the South Sundown Island chick known to be at Aransas was not found on today’s flight, so one chick can be added to the peak flock size for the 2009-10 winter (244+21=265).  It is not known if the entire South Sundown Island family group was overlooked on today’s flight, or possibly the chick has died and its parents were sighted off of their territory but not identified as such during the flight. 

January 5th - Recap of whooping cranes (264) found at Aransas and Oklahoma:

 *   The presence of one chick last seen in Oklahoma makes the current estimated flock size 264, including 20 chicks.

The discovery of 19 additional cranes is really good news.  If cranes moved around during the flight, I am concerned that perhaps this tally is artificially high by a few birds due to double counting them.  Future census flights will attempt to pin this down.  The current estimated flock size of 264 is surprisingly high but indicates that survival between spring and fall, 2009 was excellent.  The 21 wintering chicks that successfully migrated out of the 22 fledged in Canada added to the estimated flock size of 247 in spring, 2009 meant that a maximum of 268 cranes could have arrived at Aransas this fall.  One crane seen injured in Saskatchewan in the fall migration is believed to have perished.  The fact that we are accounting for 265 out of the potential 267 is excellent news.

 Migration Update:  The solitary whooping crane near Medford, Oklahoma was last seen Christmas Day.  It apparently has moved further south.  Four cranes in the second week in December west of Mad Island Preserve in Matagorda County Texas about 40 miles northeast of Aransas have moved on and presumably were seen on today’s census flight.  Two cranes that have been staying east of Tivoli about 15 miles north of Aransas were re-located on today’s flight in the Hynes Bay Unit of the Guadalupe Delta Wildlife Management Area operated by Texas Parks and Wildlife.

 Habitat Use and Food Resources:  Tides have lowered somewhat with about 30% of the mud flats dry on San Jose Island.  However, few observations have been made this winter of cranes feeding in open bay habitat, and only 6 cranes were in open bay habitat on today’s flight.  Salinities in San Antonio Bay are currently 14 parts per thousand, low enough that the cranes are drinking directly from the salt marsh.  On today’s flight, 65 cranes were located in unburned uplands, 10 were on refuge prescribed burns, 12 were at feeders on private lands, and 2 were on shell roads.  The presence of so many cranes in the uplands and cranes traveling longer distances than usual into uplands is indicative of food scarcity.  A crab count conducted December 18^th found only 1 crab.  No commercial crab traps were sighted on today’s flight, another indication that crab populations are at low levels.   The cranes since Christmas have not been observed catching blue crabs, whereas before that, some crabs were still being taken.  A few wolfberries were still available to the cranes the week before Christmas but have tapered off since then.  With blue crabs in very short supply and the wolfberry crop finished for the year, the cranes are entering the period of the winter when food shortages sometimes occur and the cranes end up using up fat reserves to survive.

Flight Conditions:  Visibility was excellent for most of the flight.  Due to reported crane movements, the search area was expanded much further out into upland areas.  This turned out to be very important in finding additional cranes.  Eight cranes were found in an area rooted up by hogs in the former farm field enclosure across the refuge’s East Shore Road about 0.7 miles from the salt marsh.  Twelve cranes were sighted at feeders at Welder Flats, 8 of them at a location that is rarely searched.  Seven cranes were found northwest of the refuge’s Burgentine Lake where cranes had been reported back on December 10th.  The largest group size observed was 8 birds seen both on the uplands on San Jose and at a game feeder at Welder Flats.  Large groups seen in salt marsh included 7 birds on the south end of Matagorda Island and 6 on Lamar’s Cow Chip Bayou.                                                       

Tom Stehn

Christmas Report - December 2009

Since my last census flight on 12/10/09, I have received confirmed reports of 6 more whooping cranes in the Aransas-Wood Buffalo population, including two more chicks.  So the estimated flock size of 238 has now been increased to 244 (223 adults + 21 chicks).  The 21 chicks accounted for indicate very good survival from the 22 that fledged in Canada.  The following are the 6 cranes added since my flight:
2+1 on a part of the refuge I did not fly over were reported by the refuge fire crew 2 days in a row, including the afternoon I was flying.
2 + 0 flown directly over but not seen on the Lamar Peninsula - they were reported by a refuge volunteer walking his dog that saw my plane go over them. They were in uplands so I can see how I missed them.
0+1 confirmed 12/14/09 in northern OK about 30 miles east of Salt Plains NWR. The juvenile was by itself with no sandhill's around.

My next flight may not be until the first week in January. I hope and expect the flock total to go up a few more to at least reach the 247 present last spring.

Tom Stehn, Aransas National Wildlife Refuge

Update: December 17, 2009

The third aerial census of the 2009-10 whooping crane season was conducted December 10, 2009 in a Cessna 210 piloted by Gary Ritchey of Air Transit Solutions of Castroville, Texas with USFWS observer Tom Stehn.  Sighted on the flight were 211 adults and 19 juveniles = 230 total.  This was an increase of 20 cranes since the previous flight conducted December 2nd.  With 230 at Aransas and 8 known to still be in migration, currently 238 whooping cranes can be accounted for.  I am expecting up to 22 juveniles based on August fledging surveys done on the nesting grounds by CWS.  With that number of juvenile produced, the flock may experience a break-even year with a flock total around 247 expected. 

 December 10^th - Recap of whooping cranes (230) found at Aransas on the aerial:

*   Since 6 family groups were present on Matagorda Island on the December 2^nd flight, it is possible that one family group was overlooked on today’s flight.  However, it is also possible a Matagorda Island family group from N. Power Lake had moved over to N. Shoalwater Bay where there was an additional family on today’s flight.

Migration Update:   Cold fronts that reached Aransas on December 4th and 9^th helped 20 additional cranes complete their 2,400-mile long migration.  Additional cranes are known to still be in migration.  Four were present at Quivira NWR on December 7^th even though the marshes were about 90% frozen.  Four were recently sighted west of Mad Island Preserve in Matagorda County Texas about 40 miles northeast of Aransas.  Two cranes that have been staying east of Tivoli about 15 miles north of Aransas were located on today’s flight in the Hynes Bay Unit of the Guadalupe Delta Wildlife Management Area operated by Texas Parks and Wildlife.

Crane Identities:  We are not sure if the Lobstick pair has returned this fall.  However, 2 cranes that may have been the Lobsticks were sighted on the Lobstick territory on December 9 and 10.  If present, the Lobstick male is 31 years old.

Habitat Use:  Tides measured at the refuge boat ramp were high (2.7 feet).  Salinities currently at 8 parts per thousand in San Antonio Bay have dropped noticeably in November and December so that the cranes are drinking directly from the marsh and have stopped making flights to fresh water dugouts.  An extremely heavy rain event on November 20^th with some coastal areas getting up to 16 inches has filled refuge dugouts and swales and flooded portions of the uplands on San Jose Island and Welder Flats.  Conditions are very wet.  Since that rain event, some blue crabs seem to have moved into the marshes, and some cranes have recently been observed catching blue crabs 2-3 inches in size.  However, 65 cranes on today’s flight were sighted on uplands. These cranes were mostly foraging on patches of bare ground, some flooded and some dry.  This behavior is indicative of a less than optimal food situation for the cranes.  Although some wolfberry flowers are still present in the marshes, few berries are present and have stopped making up a significant part of the crane diet.  An additional 5 cranes on today’s flight were on a shell road in the uplands.  No cranes were at game feeders or in open bay habitat, and there are currently no prescribed burns in the crane area.  The largest group size observed was 8 birds seen on the uplands on San Jose accompanied by sandhill cranes.  More black mangrove was noted on Ayes and Roddy islands. 

Flight Conditions:  Visibility was good for most of the flight, but darker overcast at times made for somewhat challenging viewing conditions.  Due to limited flight hours, the aircraft was usually kept at 140 knots making it a lively task to find all the cranes.  Total flight time was 4.6 hours and we felt a very good count was achieved despite some crane movements that had to be sorted out as cranes moved to and from the uplands.

 Tom Stehn, Aransas National Wildlife Refuge

Update December 14, 2009

The second aerial census of the 2009-10 whooping crane season was conducted 02 December 2009 in a Cessna 210 piloted by Gary Ritchey of Air Transit Solutions of Castroville, Texas with USFWS observer Tom Stehn.  Visibility was very good for most of the flight, but mid-day winds gusting to 25 from the northwest made for a bumpy ride and made the made the task of finding cranes more difficult.  Sighted were 191 adults and 17 juveniles = 208 total.  This was an increase of 117 cranes since the last flight conducted November 12th.  I am expecting up to 22 juveniles based on August fledging surveys done on the nesting grounds by CWS.  With that number of juvenile produced, the flock may experience a break-even year with a flock total around 247 expected.

 November 12^th - Recap of cranes (208) found at Aransas on the aerial:

Migration Update:   Cold fronts that reached Aransas on November 16, 20, 24, and 30 helped the cranes complete their 2,400-mile long migration that had begun 2 months ago for some birds.

Additional cranes are known still in migration in KS, OK, and TX, although numbers are much lower than the big wave of cranes that moved through OK and KS in mid-November.  Three other whooping cranes are presently near the coast.  On December 1^st, one whooping crane was confirmed in a flock of sandhills near Collegeport, about 50 miles northeast of Aransas. Two cranes have been staying north of Tivoli about 15 miles north of Aransas.  The addition of these 3 cranes brings the estimated total on the coast to 211.

Crane identities: The Mustang Lake pair of cranes visible from the refuge observation tower arrived approximately November 24^th.

Habitat Use:  Tides measured at the refuge boat ramp were high (2.5 feet).  The marshes on San Jose Island were notably flooded with large expanses of open water.  Salinities dropped noticeably in November so that the cranes are drinking directly from the marsh and have stopped making flights to fresh water dugouts.  Salinities on 12/02 were measured at 15 parts per thousand (ppt) at the refuge boast ramp and at 5 ppt in the adjacent marsh.  The refuge received 7.8 inches of rain in November as El Nino ended the drought.  The largest rain received was 4.35 inches on November 20^th.  Other areas including Rockport and Lamar got between 12 and 16 inches of rain during that same storm event.

The cranes have responded to the flooded conditions with 33 cranes seen on uplands during today’s flight.  I’ve seen this before when cranes utilized freshly flooded uplands with Aransas having received additional rain December 1^st.  Two cranes were near an upland crane feeder on the Lamar Peninsula.  No cranes were in open bay habitat, and there are currently no prescribed burns in the crane area.  The largest group size observed was 7 birds seen on in salt marsh on the south end of Matagorda Island.   Numerous photographs were taken to document the spread of black mangrove into the crane area.

Tom Stehn, Aransas National Wildlife Refuge

Update: November 18, 2009

The first aerial census of the 2009-10 whooping crane season was conducted 12 November, 2009 in a Cessna 210 piloted by Gary Ritchey of Air Transit Solutions of Castroville, Texas with USFWS observer Tom Stehn. Weather conditions were ideal during the 4-hour flight with sunshine and light east winds. Sighted were 87 adults and 4 juveniles = 91 total. Based on August fledging surveys done on the nesting grounds by CWS, I am expecting up to 22 juveniles. With that number of juvenile produced, the flock may experience a break-even year with a flock total around 247 expected.

November 12th - Recap of cranes (91) found at Aransas on the aerial:

	Adults + young
Refuge	34 + 1 = 35
Lamar	6 + 1 = 7
San Jose	22 + 1 = 23
Matagorda	16 + 1 = 17
Welder Flats	9 + 0 = 9
farm fields	-
Total	87 + 4 = 91

Migration Update: The first whooping crane arrival at Aransas was reported the morning of October 17th by refuge staff going over to Matagorda Island that saw a pair. This sighting was just one day after the average first whooping crane arrival date of October 16th. A cold front that reached Aransas early on 10/16 brought great migration conditions through 10/17 that aided the arrival of the first migrants. The next strong cold front at Aransas on the afternoon of 10/26 brought multiple reports of sandhill cranes moving through Texas and I had my first sighting of 125 sandhills in the farm fields north of the refuge on November 27th. A cold front October 30th brought favorable migration conditions lasting through November 5th. The next front on November 9th brought favorable migration conditions through November 12th.

Minimum # of Cranes
Date Known Present Notes
October 01 2 2 cranes over-summer at Aransas in 2009
October 17 4 first known presence of 2 migrants.
October 19 5 a single was seen in flight over Holiday Beach.
November 4 7 a pair seen on Matagorda Island
November 5 9 Johnson Ranch pair arrives on Lamar
November 7 12 Newcomb Bend family group arrives on Lamar
November 9 26 Black Skimmer tour boat reports 14 refuge additions.
November 12 91 first aerial census covers all of the crane range.

From this and weather records, it appears that a low number of whooping cranes reached Aransas in the second half of October and the first week in November, but quite a few cranes arrived between November 7-12. These later than average arrivals were simply due to birds not moving down the flyway. The migration appears to be about a week later this year than average. Last year, we flew on November 14th and tallied 239 cranes, quite a difference from the 91 counted on today’s flight. Numerous whooping cranes have been reported November 2-11 in Kansas and Oklahoma, including 39 at Quivira NWR in central Kansas on November 10. Quivira at one point had 36 cranes together, a record flock size for whooping cranes in migration. A flock of 32 was seen the following day by Salt Plains NWR in Oklahoma. The next strong pacific cold front is forecast to reach Aransas on November 16th, which I think will allow a large number of additional whooping cranes to reach Aransas.

Habitat Use: Tides were an estimated 1 foot above what I consider to be high water levels for the crane area. The high water levels were a result of Hurricane Ida that crossed the Gulf and reached Alabama as a tropical storm on November 10th. Ida raised tides 2.5 feet along the central Texas beaches. The cranes responded to the high water by being mostly in vegetated marsh, with 19 cranes on uplands next to the marsh. The distribution seen on today’s flight looked like the cranes were mostly responding to wolfberries that seems to have had a good crop this year.

Not a single commercial blue crab trap was seen in the crane area, including in the shallow bays edges next to the crane marshes. This is unusual and indicative of the poor harvest that has been ongoing all summer caused by the drought and insufficient inflows reaching the crane area. Marsh salinities are approximately 24 ppt and continue above the threshold when whooping cranes must seek out fresh water to drink. Two cranes were observed on today’s flight at a fresh water dugout. Two cranes were observed at a private game feeder. The largest group size observed was 5 birds seen on a high salt prairie at Welder Flats.

Tom Stehn, Aransas National Wildlife Refuge

This report is seasonal and dependant upon the migration habits of the Whooping Cranes.

Tom Stehn, Whooping Crane Coordinator
U.S. Fish and Wildlife Service
Aransas NWR
P.O. Box 100   Austwell, TX 77950
(361) 286-3559 Ext. 221   fax (361) 286-3722  E-mail:  tom_stehn@fws.gov
 

birdRockport.com expresses great appreciation to Tom Stehn at the 

Aransas National Wildlife Refuge and for his insightful reports.