Of late I have been borderline obsessed with documenting the objects impaled by Loggerhead Shrikes. As with most scientific pursuits, one is left with more questions than answers. But it's OK because that's how we learn things, right?
One of the most common items I see impaled by Loggerhead Shrikes on the eastern plains of Colorado is the Lesser Earless Lizard (LEEL, Holbrookia maculata). Many years ago (20+?) I saw a LEEL impaled on a fence east of Eaton, Colorado (Weld) that showed very prominent, bright yellow spheres protruding from the ripped open body cavity. What were the yellow spheres? Gonads? No, too many of them. Globs of subcutaneous fat? No, too regular in size and shape. Tumors? What? I sent my photo to a herpetologist at CSU who shall remain nameless, may he rest in peace, and he replied he did not know what they were. Over the last couple years during my renewed fascination with shrike larder, again I have seen these yellow spheres regularly associated with certain LEEL. Today I got photos from avid birder/herper Joey Kellner who recognizes female LEEL from male ones, and who saw both impaled by Loggerhead Shrikes this past weekend in southeastern CO, and who recognized the yellow objects only near females as EGGS! Why didn't I think of that? Why didn't the herpetologist to whom I sent my old photo recognize that? Well, part of the answer might come from something another person said. My botanist/birder friend Dave Steingraeber sent the recent photo below taken on the Pawnee Grasslands last week of impaled LEEL and associated yellow spheres to his colleague, retired herpetologist Gary Packard. Dr. Packard said, "...they're oviductal (i.e., forming) eggs. The shell had not been formed as yet, so you're seeing the embryo and yolk. If shrikes were energy conscious, they'd go for the eggs and leave the rest!" Aha, eggs without shells.
Besides being eye-catching, these yellow eggs look very fatty, even greasy. I would agree with Dr. Packard they are probably highly nutritious. And shrikes know their special, so much so, they occasionally remove them from the scene of the lizard and hang them separately (this photo from Larimer CR5 last week). I have also seen ants and other insects like flies attending these eggs. During one of our recent "shrikin' " expeditions, Rachel Hopper got a photo of a lizard egg on a wire that shows myriad, very tiny, black, organic dots on the wire within millimeters of the egg. Yet another mystery. Eggs? Of what? Fecal spots of an egg-scavenging insect? To be determined.
So, now, thanks to Joey and Dr. Packard, we know the answer to one of the world's greatest mysteries. Now if we could just understand politics, and the black dots.
Dave Leatherman
Fort Collins
One of the most common items I see impaled by Loggerhead Shrikes on the eastern plains of Colorado is the Lesser Earless Lizard (LEEL, Holbrookia maculata). Many years ago (20+?) I saw a LEEL impaled on a fence east of Eaton, Colorado (Weld) that showed very prominent, bright yellow spheres protruding from the ripped open body cavity. What were the yellow spheres? Gonads? No, too many of them. Globs of subcutaneous fat? No, too regular in size and shape. Tumors? What? I sent my photo to a herpetologist at CSU who shall remain nameless, may he rest in peace, and he replied he did not know what they were. Over the last couple years during my renewed fascination with shrike larder, again I have seen these yellow spheres regularly associated with certain LEEL. Today I got photos from avid birder/herper Joey Kellner who recognizes female LEEL from male ones, and who saw both impaled by Loggerhead Shrikes this past weekend in southeastern CO, and who recognized the yellow objects only near females as EGGS! Why didn't I think of that? Why didn't the herpetologist to whom I sent my old photo recognize that? Well, part of the answer might come from something another person said. My botanist/birder friend Dave Steingraeber sent the recent photo below taken on the Pawnee Grasslands last week of impaled LEEL and associated yellow spheres to his colleague, retired herpetologist Gary Packard. Dr. Packard said, "...they're oviductal (i.e., forming) eggs. The shell had not been formed as yet, so you're seeing the embryo and yolk. If shrikes were energy conscious, they'd go for the eggs and leave the rest!" Aha, eggs without shells.
Besides being eye-catching, these yellow eggs look very fatty, even greasy. I would agree with Dr. Packard they are probably highly nutritious. And shrikes know their special, so much so, they occasionally remove them from the scene of the lizard and hang them separately (this photo from Larimer CR5 last week). I have also seen ants and other insects like flies attending these eggs. During one of our recent "shrikin' " expeditions, Rachel Hopper got a photo of a lizard egg on a wire that shows myriad, very tiny, black, organic dots on the wire within millimeters of the egg. Yet another mystery. Eggs? Of what? Fecal spots of an egg-scavenging insect? To be determined.
So, now, thanks to Joey and Dr. Packard, we know the answer to one of the world's greatest mysteries. Now if we could just understand politics, and the black dots.
Dave Leatherman
Fort Collins
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