SJF February Summary

by Carl Strang

Beginning in the middle of the month, I went through all of St. James Farm Forest Preserve seeking the great horned owl nest. I did not find it, but did create an inventory of 25 large tree cavities where an incubating owl might not be visible from the ground. An additional possibility would be a hawk nest in the dense top of one of the spruces. Twice I saw an owl, presumably the male if they are nesting this year, in the same north central portion of the main forest. In past observations elsewhere, the male usually perched in the vicinity of the nest. I will continue to monitor the suspect cavities, but may need to see branched young later in the season to narrow down possibilities further.

I was able to eliminate this cavity, as it was otherwise occupied.

I was able to eliminate this cavity, as it was otherwise occupied.

Some photo processing in the computer makes the raccoon easier to see.

Some photo processing in the computer makes the raccoon easier to see.

I had not seen or heard a pileated woodpecker on the preserve for more than 6 weeks (though occasionally I heard suspicious loud, spaced tapping sounds), but in the second half of February heard or saw one on three different days. The one close sighting was of a male.

The pileated’s tongue-spear in action.

The pileated’s tongue-spear in action.

American coots and large numbers of mallards were a continuing presence on the stream. For much of the month the Canada geese roosting at Blackwell frequently passed over St. James Farm in large numbers, occasionally stopping to graze the lawns and meadow areas. Geese began to break off into pairs as ponds opened up during the last third of February. Interesting bird sightings included a bald eagle flying over, and a hermit thrush on February 16. Migrating sandhill crane flocks began to pass over beginning on the 21st. A small group of white-throated sparrows in the eastern part of the main forest were the first observed on the preserve this year. The first red-winged blackbirds arrived, and eastern bluebirds became a more consistent presence in the last part of February.

This male eastern bluebird seemed to be staking a claim in a corner of the grounds adjacent to a pair of bluebird houses.

This male eastern bluebird seemed to be staking a claim in a corner of the grounds adjacent to a pair of bluebird houses.

Fox squirrels fed heavily from Norway spruce cones in the south forest, and on tree buds elsewhere. Skunk and deer activity was much as described for January. The preserve’s deer minimally are a group of 3 does, a group of 2 deer which occasionally associate with those does, and a single buck. The snow was never deep enough to discourage raccoons. A mink used a den off the south edge of the pond in the preserve’s northwest corner.

Along the way during the owl nest search I found this curiosity.

Along the way during the owl nest search I found this curiosity.

The deer pelvic bone was well gnawed by rodents.

The deer pelvic bone was well gnawed by rodents.

The bone has been on this buckthorn twig long enough for the twig to grow several long branches.

The bone has been on this buckthorn twig long enough for the twig to grow several long branches.

The large area of restoration brush clearing in the main forest was expanded greatly by District staff, generally following the route of the new trail mapped in the preserve’s master plan. Among the more interesting plants encountered during the owl nest search were two of the most massive black walnuts I have ever seen, and a prickly-stemmed greenbrier (Smilax tamnoides).

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St. James Farm January Summary

by Carl Strang

Part of my preserve monitoring practice is to write a monthly summary of observations. Today I am sharing the one from January just past:

Most of January was seasonably cold, with significant warming the last few days of the month. Little snow fell, on two occasions about an inch at a time.

Fox squirrels enjoyed the occasional sunny days, and feasted on the abundant walnuts.

Fox squirrels enjoyed the occasional sunny days, and feasted on the abundant walnuts.

Fresh snow at the beginning of the year permitted a general assessment of mammal activity in the preserve. Raccoons appear to be more abundant here than at other preserves I have monitored, with the greatest concentration of activity in the northern portion of the main forest. Skunks were surprisingly active through January, coming out even on nights when the temperature dropped into the teens. This is in contrast to other preserves, where overnight temperatures in the 30’s, at least, were required until the start of the mating season in February. A couple chipmunks also emerged from their holes, likewise unusual in mid-winter. At least one mink includes the stream and the northern portion of the main forest in its territory. Cottontails were scattered throughout, though their activity was mainly around the forest edges. A very few opossums, perhaps no more than 4-5, were active on the preserve. Meadow voles, short-tailed shrews and white-footed mice are common, and occasionally I encountered tracks of masked shrews (vole, mouse, and small shrew identifications based on habitat and regional abundance as opposed to prairie vole, deer mouse and least shrew alternative possibilities). Two domestic cats occasionally moved through the northern edge of the forest, possibly connected to the houses off the preserve’s NE corner.

This coyote caught a meadow vole shortly after I took this photo.

This coyote caught a meadow vole shortly after I took this photo.

Coyotes covered the entire preserve. Early in January I watched a slightly scruffy looking individual with much red and black in its fur catch and consume a vole in the meadow alongside the entrance drive. At the end of January, a coyote with much more of a white color dominance, very alert and fat looking, passed through the western part of the forest. Tracks revealed that two coyotes occasionally hunt together. I did not detect a consistent activity pattern in the deer. At times 4-5 moved together, that group size suggesting does. Elsewhere, single sets with the foot placement of bucks indicated at least one individual of that gender remains on the preserve.

Canada geese in DuPage County are grazers in winter.

Canada geese in DuPage County are grazers in winter.

Geese maintained a roost at south Blackwell through the month. Most mornings they flew over St. James Farm heading east, but occasionally a few dozens to a few hundred stopped and grazed the preserve’s lawns and meadows.

Part of a large goose flock feeding on a SJF lawn.

Part of a large goose flock feeding on a SJF lawn.

Over a hundred mallards utilized the newly reconfigured stream bed in the last half of January. One of them attempted to choke down a leopard frog that apparently had been unable to tunnel deep enough into the rocky stream edge when the weather turned cold in December. On another day a coot joined the ducks in the stream. The only pileated woodpecker observation during the month was one calling in the western forest on January 4.

White-breasted nuthatches are common in this preserve’s forests.

White-breasted nuthatches are common in this preserve’s forests.

Cardinals and chickadees began to sing, and downy woodpeckers to drum, in the last half of the month. There are at least 7 chickadee groups of various sizes scattered over the preserve. 1-2 adult red-tailed hawks frequently hunted the preserve’s meadows.

A red-tailed hawk scans a meadow for vole movements.

A red-tailed hawk scans a meadow for vole movements.

St. James Farm received a gratifying amount of restoration attention in January, with seeds scattered over the meadow or prairie area north of the stream, and the clearing of buckthorn and other undesirable woody plants from an extensive portion of the western forest.

 

Skunk Surprise

by Carl Strang

Snow that fell around the turn of the year has provided good tracking opportunities at St. James Farm Forest Preserve. As I walk the new survey routes I established in December, I am beginning to assemble a sense of the general mammal presence and activities on the preserve. For instance, I found that cottontail rabbits are much more abundant and widely distributed than my earlier first impression indicated. The species list also is growing. For example, I ran across some mink tracks on New Year’s Day.

At first I was excited, because they seemed smaller and less round than mink tracks usually are, but they proved to be those of a mink rather than the locally rarer long-tailed weasel.

At first I was excited, because they seemed smaller and less round than mink tracks usually are, but they proved to be those of a mink rather than the locally rarer long-tailed weasel.

With minimal wandering the mink, possibly a female by the small size, came straight out of the forest and into the newly reconfigured stream.

With minimal wandering the mink, possibly a female by the small size, came straight out of the forest and into the newly reconfigured stream.

A new species record is welcome, but even more welcome was a bit of a mystery that came the next day.

Skunk tracks in the snow!

Skunk tracks in the snow!

This was surprising because, in my previous experience, skunks didn’t emerge from their dens in early January unless the temperature overnight was at least 30-40F. It had been in the mid-teens. As I followed my route I was able to trace the skunk’s course, roughly a straight line to the preserve’s boundary against a residential neighborhood. Later I backtracked this individual to a contorted tangle of footprints in a difficult to negotiate (for me) spot in the woods just north of Butterfield Road. I wasn’t able to cut this skunk’s entry into that area, so perhaps its den is there.

That wasn’t the end of it, though, as I soon crossed a second skunk’s trail. This was a different individual, larger and with a significantly wider straddle. Its feet were dragging significantly. Sorry, it didn’t occur to me at the time to photograph those tracks. I encountered them near where skunk #2 was exiting the preserve, again into the neighborhood to the east. As I continued my walk I was able to backtrack this second animal, occasionally cutting his trail and occasionally following it.

Here is the habitat map of northern St. James Farm. M shows where the mink was, S1 is the narrow-straddle skunk, and S2 is the wider-straddle individual. Solid lines show where I followed the tracks, dashed lines indicate areas between places where I cut the animals’ trails.

Here is the habitat map of northern St. James Farm. M shows where the mink was, S1 is the narrow-straddle skunk, and S2 is the wider-straddle individual. Solid lines show where I followed the tracks, dashed lines indicate areas between places where I cut the animals’ trails.

Ultimately I traced a good mile that skunk #2 had hiked. No wonder its feet were dragging at the end, and the foot drag gradually vanished as I backtracked it. It had crossed the parking lot after visits to the ranger residence and the round office building. Before that it had crossed the trail of skunk #1 (close enough in time that my skills are inadequate to say which individual passed that way first) after taking the Prairie Path tunnel under Butterfield Road. It had emerged from the woods south of Butterfield, still on the preserve, but a locked gate blocked my further progress.

This is the kind of traveling I expect in February, when the striped skunk mating season arrives. Then, they are much more likely to come out on the colder nights. As this winter progresses I look forward to learning whether St. James Farm’s skunks in the winter of 2015-16 habitually emerge to wander more often and in colder weather than skunks in other years in other places.

 

Striped Skunk Dossier

by Carl Strang

As striped skunks complete their mating season, this seems an appropriate time to share my dossier of observations on the species.

Skunk, Striped

Striped skunk

Striped skunk

I rarely saw skunks around Culver as a child, perhaps because of their nocturnal activity pattern. Saw one on a road south of town near S.R. 110 while on a run, at dusk, as a teenager. I took plaster castings of tracks at the Bird Sanctuary, Culver Military Academy. Later I saw some in the early evening, visiting picnic grounds at the state park on South Mountain in Pennsylvania. They moved with a somewhat rolling, unhurried walk. Individuals brought to Willowbrook in live traps almost invariably spray as soon as the trap is opened. The spray has a very sticky, lasting quality, and causes a sickening sensation when fresh and concentrated. Youngsters discover their spray ability when 6-9 weeks old. The distinctive black and white color pattern almost certainly is aposematic. That pattern is highly variable in detail, i.e., width and length of stripe, amount of white on head, and number and position of scattered small white spots. The skin beneath is white or black, corresponding to the fur color. Stomping, used as a threat, essentially is an emphatic dancing from one front foot to the other. It is employed against both conspecifics (littermates) and potential predators. The tracks have 5 toes showing, both front and back feet. In suitable substrates, the toenails of the front feet register distinctively distant from the ends of the toes. When toenail marks are missing, the track gives the impression of a miniature cat track (though with the extra toe). Generally, the entire footprint appears as a solid, unlobed block; creases across the soles of the feet are evident in medium-consistency substrates. Tracks rarely are encountered, however. Apparently there is very little activity in winter.

Skunk tracks, hind on left, fore (showing long toenail marks) on right

Skunk tracks, hind on left, fore (showing long toenail marks) on right

17/18FE86. I followed a fresh skunk trail. Gaits in deep snow (4-8″) were diagonal walk and lope, primarily, on an early spring ramble. This skunk ate some mushy crabapples from the previous fall. It went about half a mile on Willowbrook preserve plus an unknown distance on adjacent properties. The den (near Willowbrook picnic grounds) was a tunnel dug in a well-drained location, on an east-facing slope, sheltered by a crabapple. Tracks suggest it was shared with 1-2 cottontails.

4NO86. Diagonal walk in mud, probably the same skunk described in the previous account, at rehab area west gate.

28NO86. Sand seems to stick unusually well to the flat soles of a skunk’s feet, deposited on sticky mud to form roundish or oval spots of sand grains (Culver Fish Hatchery).

29NO86. Memorial Forest near Culver. Lope (bound?) In sand, 6″ between sets of tracks, each set 12″ long.

Sketch of track patterns in the string observed on November 29, 1986

Sketch of track patterns in the string observed on November 29, 1986

28JA87. One or perhaps more than one skunk on walkabout last night in Willowbrook Back 40. Paths extremely convoluted and interweaving, not enough time to sort them out. No skunk came out of the picnic grounds burrow.

3FE87. Skunk on walkabout again, same area. Suddenly it seemed to be taking great leaps. The snow crust froze in open spots at night, so the skunk did not break through in those places.

5FE87. Skunk pulled dead shrew (previously cached by fox) to center of trail but left it.

27OC87. A skunk ran across the road in our Warrenville neighborhood (Summerlakes subdivision) in early evening (around 6pm). It elevated the middle of its tail, giving it a strange, double-humped appearance.

18OC88. In Cactus Camp prairie, tracks show where a skunk dug out a yellow jacket nest recently. A few wasps still were flying in and out.

12JA89. A dead skunk on Park Boulevard at Willowbrook, came out mid-winter.

8SE89. Skunk diagonal walk, flat soft topsoil. Hind foot landing in front of and slightly overlapping front foot. HF 1-5/16″ wide x 1.25″ long.

8JA90. Willowbrook. On the night of the 5th or 6th, a skunk was out. Those were warm nights.

7MR90. Willowbrook. Skunks have been very active the past couple of nights. One has a burrow at the south edge of Willowbrook preserve, south of the stream. They made a couple stream crossings (water, not ice). One of these continued straight north all the way across the preserve.

Typical bounding gait pattern

Typical bounding gait pattern

1SE90. As I ran on the Prairie Path in Warrenville near the library in early evening, what appeared to be a large cat emerged from the vegetation at the side and then stopped in the middle of the path as I approached. Thinking to frighten it out of the way, I began to snap my fingers and accelerated. The cat was strange…it seemed to change shape. Then I saw the stripes and quickly backpedaled. It was a family of skunks, so tight together they seemed one animal in the distance in the dim light. There were at least 3 young with the mother. They had stopped and faced me, partly lifting their tails, all of which made the stripes easy to see even in the darkness. After I backed off they continued on their way.

25FE99. I found a skunk den in the far NE corner of the new Willowbrook preserve addition, under a pile of stacked old telephone pole segments. As many as 4 skunks were active on the preserve the previous night.

16FE00. A skunk on walkabout at Willowbrook last night, the first sign of skunk activity this winter there.

12SE05. Caesar Creek campground, southeastern Ohio. There is much evidence of skunks in the area. In the dusk, a large beautiful individual whose broad back stripes had joined, giving it a white back with just a little black between on the lower back, passed my campsite. Later in the dark, a smaller individual was digging grubs in the lawn of the adjacent campsite. This one was all black with a tuft of white on the head and another at the tip of the tail. It turned away when I shined a light in its eyes, coming as close as 15 feet. It moved slowly, its head sweeping back and forth sniffing, but when finding something to dig it moved quickly, excavating and moving on within about 3 seconds. The next morning I took photos of some of the holes, and of a pile of scats. The holes were mostly neat, ½” diameter, dug out on one side with toenail marks clear, occasional larger ones up to 2” diameter. The scats were stacked weasel fashion, each ½” diameter X 2” long, 3 pieces, one broken with a tiny root sticking out.

One of the holes described on September 12, 2005

One of the holes described on September 12, 2005

The scats described on September 12, 2005

The scats described on September 12, 2005

19JA11. Mayslake. From the night before last, which was the warmest this month (only dropping into the 20’sF), tracks of a skunk. It may have originated from the known den in the north stream corridor. Its winding trail covered much of the north stream corridor prairie, parts of the main prairie, cut from the small savanna at the north end of the prairie across the driveway’s turning circle into the strip of vegetation along the west edge of the preserve, wound through that as it worked its way north, eventually crossed the driveway again at the 31st Street Woods, and continued heading east along the north end of the parking lot marsh.

21JA11. Mayslake. I went to the known skunk den hole in the north stream corridor to see if it was the home of the skunk I tracked 2 days ago. It had not been entered or exited. I picked up the skunk’s trail where it had gone around the N end of the parking lot marsh, and followed it to a hole in the top of the ridge between that marsh and the stream (created when the marsh was excavated), and even with the marsh’s center. It appeared that the skunk had emerged and entered the hole, but the tracks were obscured by large ice crystals developing around the hole’s edge.  Later it occurred to me how unusual those crystals were. Are they growing on moisture from the skunk’s breath?

Skunk den entrances usually are around 6 inches in diameter.

Skunk den entrances usually are around 6 inches in diameter.

23FE11. Mayslake. For a time I mistook a skunk’s trail for that of a mink. What threw me off was the first impression, where the toes spread an unusual amount in thin snow over slick ice. I failed to attend the other tracks carefully enough for a long time, though I was somewhat bothered by the long toenails and the animal following the trail rather than the lake edge. As I approached the den near the friary site I saw similar tracks, confirmed much coming and going and digging at that den, then went back and found that if I had paid closer attention to all the footprints I had been following, I would have realized sooner that they were skunk tracks. The main underlying condition was the thin layer of snow over ice, with enough of a percentage of round-looking tracks resulting to sustain my error.

Mayslake Mammal Update

by Carl Strang

The deep snow is receding, now, but it certainly has posed challenges to some of our mammals.

Not all of them, though. The muskrat could function with underwater excursions from its secure lodge.

Not all of them, though. The muskrat could function with underwater excursions from its secure lodge.

Voles, the muskrat’s smaller terrestrial relatives, have enjoyed a winter relatively safe from predators. Other species have had to deal with it. We entered the mating season for skunks and raccoons, and they could not wait out the winter.

Skunks, with their relatively short legs, had a particularly difficult time until the snow crusted enough to support them.

Skunks, with their relatively short legs, had a particularly difficult time until the snow crusted enough to support them.

The snow forced this raccoon into a rare, diagonal walk gait.

The snow forced this raccoon into a rare, diagonal walk gait.

A few clear tracks confirmed that the above string was raccoon-created.

A few clear tracks confirmed that the above string was raccoon-created.

With the thaw on, and overnight lows crusting the snow, only deer and humans still are inconvenienced where the snow remains deep.

Mayslake Update

by Carl Strang

Mayslake Forest Preserve has been quiet, and for the most part remains in winter mode. Large numbers of American tree sparrows still are present, though they are wandering into an expanded portion of the preserve. For instance, one day in late January they shifted to the off leash dog area and, joined by some juncos, a couple song sparrows and a white-throated sparrow, fed on weed seeds.

Here is one tiny portion of the flock that contained more than 100 tree sparrows. One of the song sparrows is in the center.

Here is one tiny portion of the flock that contained more than 100 tree sparrows. One of the song sparrows is in the center.

In another part of the flock the tree sparrows are joined by a few juncos.

In another part of the flock the tree sparrows are joined by a few juncos.

At long last the stream corridor marsh has begun to refill.

A tiny, shallow pool had gathered by January 29.

A tiny, shallow pool had gathered by January 29.

That initial pool was perhaps 30 feet across.

That initial pool was perhaps 30 feet across.

A front brought heavy rain, then cold that froze the collected waters.

Here is the marsh two days later.

Here is the marsh two days later.

We continue to get periods of rain, and the river bulrushes have begun to collapse.

By the end of last week, perhaps 80% of the marsh had water in it again.

By the end of last week, perhaps 80% of the marsh had water in it again.

With the ground frozen, much of the rain is running off, but some is collecting in depressions like the marsh. We can hope for the rain to continue and perhaps avoid a repeat of last year’s drought.

In the meantime, skunk tracks have begun to appear, one of the early signs that spring is coming.

Literature Review: Two Mammal Studies

by Carl Strang

Our common animals are familiar enough that we may think we know all about them. There always is something new to learn, however, and this week I share two examples from recent publications.

Raccoons are not as solitary as we thought.

Raccoons are not as solitary as we thought.

Prange, Suzanne, Stanley D. Gehrt, and Stephanie Hauver. 2011. Frequency and duration of contacts between free-ranging raccoons: uncovering a hidden social system. J. Mammal. 92:1331-1342.

They used radio collars to track social associations. Though raccoons are solitary most of the time, males form long-term social groups by maintaining regular contacts, each female associates with one such group, and female-female contacts are short term. This is referred to as a fission-fusion social system.

The second study looked at the genetic geography of skunks.

The second study looked at the genetic geography of skunks.

Barton, Heather D., and Samantha M. Wisely. 2012. Phylogeography of striped skunks (Mephitis mephitis) in North America: Pleistocene dispersal and contemporary population structure. J. Mammal. 93:38-51.

They looked at mitochondrial genetics of North American skunks in relation to glacial refuge history. Today’s skunks show 4 main groups apparently isolated by glaciers and subsequently spreading. Illinois skunks show the greatest measured mix, about half from east coast-Southeast sources, a little over a quarter from the central South (Arizona to Louisiana), and the rest from the Intermountain West (no representation from the fourth, west coast group).

Skunk at Mid-day

by Carl Strang

Twice in November, when my noontime walk has taken me into the former friary site at Mayslake Forest Preserve, I have seen a striped skunk out and about. The first time it was close to a known den hole, and the sighting was a novelty. Occasionally I have encountered other nocturnal mammals, including raccoons and opossums, out in the middle of the day over the years, and though I had not seen a skunk doing so, it’s also true that skunks are less common than those other animals. But then I saw the skunk the second time.

At first the skunk looked normal enough.

It was moving in the usual gait at the usual speed, apparently stopping frequently to pause, dig a little, apparently eat an insect, and continue. But then at one point it stopped and lifted its head, turning it in various directions and sniffing. The eyes looked strange.

Was it simply squinting in the unaccustomed light?

Another possibility is that the animal is blind. This likewise would not be unprecedented. When I worked at the Forest Preserve District of DuPage County’s Willowbrook Wildlife Center, I knew of several opossums that had been brought into the clinic over the years, opossums that had been congenitally blind. They were healthy otherwise, and had functioned well enough to achieve adulthood, but had wandered into places where they got into trouble. They could not be released, however, into an unfamiliar area, and so were kept on as exhibit animals.

Skunks, likewise nocturnal, also live largely by their noses. If this one is blind indeed, it seems to be staying in a part of the preserve where it will be able to maintain itself without negative encounters with dogs or people. There is no point in trying to trap it and take it to Willowbrook. The Wildlife Center’s permit from the state requires its staff to euthanize any skunks or bats that come in, because they are the animals most likely to have rabies. I will be interested in following this skunk’s career. After all, it may not be blind at all, just odd.

Grub Control

by Carl Strang

Earlier this week a number of small, freshly dug holes appeared in scattered parts of the mansion lawn at Mayslake Forest Preserve.

The holes were small, 1-2 inches in diameter, and not very deep.

Considering the structure of the holes, their location, and the time of year, it was not a big challenge to identify them. In fact, I had seen such holes being dug one night when I was camping in Ohio in 2005.

The next day I had photographed one of those holes.

The excavator was a striped skunk, and it was after beetle grubs in the lawn. Here are my notes from that night in Ohio: “12SE05, Caesar Creek campground, southeastern Ohio. I saw much evidence of skunks in the area. In the dusk, a large beautiful individual whose broad back stripes had joined, giving it a white back with just a little black in the middle of the lower back, passed my campsite. Later in the dark, a smaller individual was digging grubs in the lawn of the adjacent campsite. This one was all black with a tuft of white on the head and another at the tip of the tail. It came as close as 15 feet, but turned away when I shined a light in its eyes. It moved slowly, sweeping its head back and forth and sniffing, but when it found something to dig it moved quickly, excavating and moving on within about 3 seconds.”

The holes at Mayslake might even have been dug by the same skunk rescued by Nikki earlier in the summer.

That skunk awaiting rescue in early July.

It can be alarming to find so many holes in your lawn, but keep in mind that the grubs could have done a lot more damage if left there. The skunk efficiently removed the grubs with the smallest of holes, incidentally aerating the lawn. The skunks strike me as being patient and economical, waiting until the grubs are big enough that they are both easy to sniff out and at their most nutritious food value. Hooray for skunks!

Nikki and the Skunk

by Carl Strang

It was a small skunk, but it was an adult, and fully potent. It had found a gap in a window well cover at the Mayslake mansion and fallen in.

Boards had been provided as a ramp, but the window well was too deep and the boards too steep for the skunk to climb out overnight.

My Naturalist colleague at Mayslake, Nikki Dahlin, is an experienced animal rescuer. She brought one of her nets and a change of clothes.

The skunk’s tail was lifted almost immediately: “I have a weapon and I know how to use it!”

The rest of us provided moral support…

… at a safe distance.

The skunk soon was on its way.

It had released some of the famous odor, but not in a directed spray.

Nikki’s net took the brunt of the emission.

Another day in the life of a Naturalist.

Fortunately such episodes are rare, and generally can be resolved with no harm to the participants.

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