Nathan et al, The situation certainly has aphids at its core. The sticky substance is aphid excrement called "honeydew". The aphids suck sap from trees, utilize the nitrogenous compounds, excrete the sugars. Many other creatures, mostly other insects, seek out the honeydew. Yellowjackets, of which the black-and-white bald-faced hornet is one, seek the honeydew as food. So do flies and many other insects. The aphids and honeydew seekers are all eaten by birds. I suspect the warblers are strictly after the aphid life forms present and are mostly unable to ingest the honeydew. Earlier in late summer and the peak of fall migration, big flycatchers like pewees and kingbirds really go after wasps, especially honeydew-attracted yellowjackets.
Nice job Matt and Thomas. Dave Leatherman Fort Collins ________________________________ From: [email protected] <[email protected]> on behalf of Nathan Pieplow <[email protected]> Sent: Monday, November 7, 2022 6:52 PM To: cobirds <[email protected]> Subject: [cobirds] Parula and Prothontary on CU Boulder campus Hello all, This morning, Matt Hofeditz found a Northern Parula on the CU campus, and later today Thomas Heinrich found a Prothonotary Warbler in the same tree with it. The two birds were seen together until dark. Their favorite tree seems to be an oak with yellow leaves at the NE corner of parking lot 310, which is on the NE corner of Regent and Broadway in Boulder. Paid public parking is available at the Center for Community (C4C), which is just two buildings farther to the east on the north side of Regent. As Dave Leatherman always reminds us, November warblers that hang out in the same area are always exploiting some kind of food source. This particular oak tree, like many oaks at this time of year, seems to have a sticky substance on its leaves that attracts hornets (and also rare warblers). I'll let Dave say what he thinks might be going on. But if the tree is feeding them well, these two warblers might hang around for a little while. Both birds venture to the surrounding trees as well. For those who might come to Boulder County from elsewhere: the juvenile Yellow-crowned Night-Heron also continues at Pella Crossing park near Longmont. It hangs out around the NW corner of the easternmost pond, where it usually either hunkers down in the woody vegetation along the waterline, or else prowls the grass right next to the walking trail in plain sight. Nathan Pieplow Boulder -- -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/cobirds?hl=en?hl=en * All posts should be signed with the poster's full name and city. Include bird species and location in the subject line when appropriate * Join Colorado Field Ornithologists https://cobirds.org/CFO/Membership/ --- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]<mailto:[email protected]>. To view this discussion on the web visit https://groups.google.com/d/msgid/cobirds/CAFhaDVJpqnea9TP546oWVzeSCmoJ47eptsz4kt2OPj0JCT%2BjkQ%40mail.gmail.com<https://groups.google.com/d/msgid/cobirds/CAFhaDVJpqnea9TP546oWVzeSCmoJ47eptsz4kt2OPj0JCT%2BjkQ%40mail.gmail.com?utm_medium=email&utm_source=footer>. -- -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/cobirds?hl=en?hl=en * All posts should be signed with the poster's full name and city. Include bird species and location in the subject line when appropriate * Join Colorado Field Ornithologists https://cobirds.org/CFO/Membership/ --- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/cobirds/PH7PR12MB73546D78A5B979F65854C192C13F9%40PH7PR12MB7354.namprd12.prod.outlook.com.
