Asked January 13, 2021, 8:34 AM EST
Anne Arundel County Maryland
A native woodpecker species called the Yellow-bellied Sapsucker can cause damage that sounds like what you are describing, though often the host trees are otherwise unscathed from this activity. Images of the bird and its characteristic damage can be viewed in this gallery: https://www.marylandbiodiversity.com/view/1152
Control options for Sapsuckers are limited to simply using a barrier to keep the birds from reaching the trunk, though this could backfire and cause them to damage other trees; it is also often impractical to apply as branches can get in the way, especially on full/low-branched evergreens like a holly. If the tree does succumb, it may be due to a combination of stress factors not limited to the tree's injuries.
You can inspect the foliage for signs of scale, a common insect pest of holly that can easily reach damaging levels. There are different species of scale, but on holly, they are usually either cottony white tufts or hard-shelled gray/brown and will be attached to the leaf undersides (usually along the midvein), small twigs, or joints in branches. Some defoliation and yellowed foliage can be indicators of a heavy scale population, though other ailments can cause similar symptoms because their effects on the tree's tissues are the same. 'Nellie Stevens' is popular partly due to its resiliency, but plants stressed by prior drought, overly-wet soil, or root injuries can become more susceptible targets for pests such as scale. Here is a page of scale information that includes the main culprits for holly:
If you do not see any pests, you can send us photographs of the plants, the symptoms they are displaying, and the conditions they are growing in, and we can assess if there are any other likely causes of decline. If the trees happen to be leafless now, then the damage (no matter the cause) is too great to treat or will be too impractical to attempt recovery. Replacement trees are probably safe to plant, though it may depend on what factor seems to be the biggest contributor to decline of the original trees.
From: Ask Extension
To: Robert O'Brien
Sent: Wed, Jan 13, 2021 1:59 pm
Subject: Re: Holly tree bark disease and death (#0003905)